new adapter classes

apps/auracast.py

@@ -522,14 +522,19 @@ async def run_assist(
             return
 
         # Subscribe to and read the broadcast receive state characteristics
+        def on_broadcast_receive_state_update(
+            value: bass.BroadcastReceiveState, index: int
+        ) -> None:
+            print(
+                f"{color(f'Broadcast Receive State Update [{index}]:', 'green')} {value}"
+            )
+
         for i, broadcast_receive_state in enumerate(
             bass_client.broadcast_receive_states
         ):
             try:
                 await broadcast_receive_state.subscribe(
-                    lambda value, i=i: print(
+                    functools.partial(on_broadcast_receive_state_update, index=i)
-                        f"{color(f'Broadcast Receive State Update [{i}]:', 'green')} {value}"
-                    )
                 )
             except core.ProtocolError as error:
                 print(

apps/gg_bridge.py

@@ -234,7 +234,7 @@ class GattlinkNodeBridge(GattlinkL2capEndpoint, Device.Listener):
             Characteristic.WRITEABLE,
             CharacteristicValue(write=self.on_rx_write),
         )
-        self.tx_characteristic = Characteristic(
+        self.tx_characteristic: Characteristic[bytes] = Characteristic(
             GG_GATTLINK_TX_CHARACTERISTIC_UUID,
             Characteristic.Properties.NOTIFY,
             Characteristic.READABLE,

bumble/att.py

@@ -29,13 +29,14 @@ import functools
 import inspect
 import struct
 from typing import (
-    Any,
     Awaitable,
     Callable,
+    Generic,
     Dict,
     List,
     Optional,
     Type,
+    TypeVar,
     Union,
     TYPE_CHECKING,
 )
@@ -43,13 +44,18 @@ from typing import (
 from pyee import EventEmitter
 
 from bumble import utils
-from bumble.core import UUID, name_or_number, ProtocolError
+from bumble.core import UUID, name_or_number, InvalidOperationError, ProtocolError
 from bumble.hci import HCI_Object, key_with_value
 from bumble.colors import color
 
+# -----------------------------------------------------------------------------
+# Typing
+# -----------------------------------------------------------------------------
 if TYPE_CHECKING:
     from bumble.device import Connection
 
+_T = TypeVar('_T')
+
 # -----------------------------------------------------------------------------
 # Constants
 # -----------------------------------------------------------------------------
@@ -748,7 +754,7 @@ class ATT_Handle_Value_Confirmation(ATT_PDU):
 
 
 # -----------------------------------------------------------------------------
-class AttributeValue:
+class AttributeValue(Generic[_T]):
     '''
     Attribute value where reading and/or writing is delegated to functions
     passed as arguments to the constructor.
@@ -757,33 +763,34 @@ class AttributeValue:
     def __init__(
         self,
         read: Union[
-            Callable[[Optional[Connection]], Any],
+            Callable[[Optional[Connection]], _T],
-            Callable[[Optional[Connection]], Awaitable[Any]],
+            Callable[[Optional[Connection]], Awaitable[_T]],
             None,
         ] = None,
         write: Union[
-            Callable[[Optional[Connection], Any], None],
+            Callable[[Optional[Connection], _T], None],
-            Callable[[Optional[Connection], Any], Awaitable[None]],
+            Callable[[Optional[Connection], _T], Awaitable[None]],
             None,
         ] = None,
     ):
         self._read = read
         self._write = write
 
-    def read(self, connection: Optional[Connection]) -> Union[bytes, Awaitable[bytes]]:
+    def read(self, connection: Optional[Connection]) -> Union[_T, Awaitable[_T]]:
-        return self._read(connection) if self._read else b''
+        if self._read is None:
+            raise InvalidOperationError('AttributeValue has no read function')
+        return self._read(connection)
 
     def write(
-        self, connection: Optional[Connection], value: bytes
+        self, connection: Optional[Connection], value: _T
     ) -> Union[Awaitable[None], None]:
-        if self._write:
+        if self._write is None:
-            return self._write(connection, value)
+            raise InvalidOperationError('AttributeValue has no write function')
-
+        return self._write(connection, value)
-        return None
 
 
 # -----------------------------------------------------------------------------
-class Attribute(EventEmitter):
+class Attribute(EventEmitter, Generic[_T]):
     class Permissions(enum.IntFlag):
         READABLE = 0x01
         WRITEABLE = 0x02
@@ -822,13 +829,13 @@ class Attribute(EventEmitter):
     READ_REQUIRES_AUTHORIZATION = Permissions.READ_REQUIRES_AUTHORIZATION
     WRITE_REQUIRES_AUTHORIZATION = Permissions.WRITE_REQUIRES_AUTHORIZATION
 
-    value: Any
+    value: Union[AttributeValue[_T], _T, None]
 
     def __init__(
         self,
         attribute_type: Union[str, bytes, UUID],
         permissions: Union[str, Attribute.Permissions],
-        value: Any = b'',
+        value: Union[AttributeValue[_T], _T, None] = None,
     ) -> None:
         EventEmitter.__init__(self)
         self.handle = 0
@@ -848,11 +855,11 @@ class Attribute(EventEmitter):
 
         self.value = value
 
-    def encode_value(self, value: Any) -> bytes:
+    def encode_value(self, value: _T) -> bytes:
-        return value
+        return value  # type: ignore
 
-    def decode_value(self, value_bytes: bytes) -> Any:
+    def decode_value(self, value: bytes) -> _T:
-        return value_bytes
+        return value  # type: ignore
 
     async def read_value(self, connection: Optional[Connection]) -> bytes:
         if (
@@ -877,11 +884,16 @@ class Attribute(EventEmitter):
                 error_code=ATT_INSUFFICIENT_AUTHORIZATION_ERROR, att_handle=self.handle
             )
 
-        if hasattr(self.value, 'read'):
+        value: Union[_T, None]
+        if self.value is None:
+            value = None
+        elif hasattr(self.value, 'read'):
             try:
-                value = self.value.read(connection)
+                read_value = self.value.read(connection)
-                if inspect.isawaitable(value):
+                if inspect.isawaitable(read_value):
-                    value = await value
+                    value = await read_value
+                else:
+                    value = read_value
             except ATT_Error as error:
                 raise ATT_Error(
                     error_code=error.error_code, att_handle=self.handle
@@ -889,20 +901,24 @@ class Attribute(EventEmitter):
         else:
             value = self.value
 
-        self.emit('read', connection, value)
+        self.emit('read', connection, b'' if value is None else value)
 
-        return self.encode_value(value)
+        return b'' if value is None else self.encode_value(value)
 
-    async def write_value(self, connection: Connection, value_bytes: bytes) -> None:
+    async def write_value(self, connection: Optional[Connection], value: bytes) -> None:
         if (
-            self.permissions & self.WRITE_REQUIRES_ENCRYPTION
+            (self.permissions & self.WRITE_REQUIRES_ENCRYPTION)
-        ) and not connection.encryption:
+            and connection is not None
+            and not connection.encryption
+        ):
             raise ATT_Error(
                 error_code=ATT_INSUFFICIENT_ENCRYPTION_ERROR, att_handle=self.handle
             )
         if (
-            self.permissions & self.WRITE_REQUIRES_AUTHENTICATION
+            (self.permissions & self.WRITE_REQUIRES_AUTHENTICATION)
-        ) and not connection.authenticated:
+            and connection is not None
+            and not connection.authenticated
+        ):
             raise ATT_Error(
                 error_code=ATT_INSUFFICIENT_AUTHENTICATION_ERROR, att_handle=self.handle
             )
@@ -912,11 +928,11 @@ class Attribute(EventEmitter):
                 error_code=ATT_INSUFFICIENT_AUTHORIZATION_ERROR, att_handle=self.handle
             )
 
-        value = self.decode_value(value_bytes)
+        decoded_value = self.decode_value(value)
 
-        if hasattr(self.value, 'write'):
+        if self.value is not None and hasattr(self.value, 'write'):
             try:
-                result = self.value.write(connection, value)
+                result = self.value.write(connection, decoded_value)
                 if inspect.isawaitable(result):
                     await result
             except ATT_Error as error:
@@ -924,9 +940,9 @@ class Attribute(EventEmitter):
                     error_code=error.error_code, att_handle=self.handle
                 ) from error
         else:
-            self.value = value
+            self.value = decoded_value
 
-        self.emit('write', connection, value)
+        self.emit('write', connection, decoded_value)
 
     def __repr__(self):
         if isinstance(self.value, bytes):

bumble/device.py

@@ -53,7 +53,7 @@ from pyee import EventEmitter
 
 from .colors import color
 from .att import ATT_CID, ATT_DEFAULT_MTU, ATT_PDU
-from .gatt import Characteristic, Descriptor, Service
+from .gatt import Attribute, Characteristic, Descriptor, Service
 from .host import DataPacketQueue, Host
 from .profiles.gap import GenericAccessService
 from .core import (
@@ -2221,7 +2221,7 @@ class Device(CompositeEventEmitter):
                         permissions=descriptor["permissions"],
                     )
                     descriptors.append(new_descriptor)
-                new_characteristic = Characteristic(
+                new_characteristic: Characteristic[bytes] = Characteristic(
                     uuid=characteristic["uuid"],
                     properties=Characteristic.Properties.from_string(
                         characteristic["properties"]
@@ -4920,16 +4920,84 @@ class Device(CompositeEventEmitter):
             self.gatt_service = gatt_service.GenericAttributeProfileService()
             self.gatt_server.add_service(self.gatt_service)
 
-    async def notify_subscriber(self, connection, attribute, value=None, force=False):
+    async def notify_subscriber(
+        self,
+        connection: Connection,
+        attribute: Attribute,
+        value: Optional[Any] = None,
+        force: bool = False,
+    ) -> None:
+        """
+        Send a notification to an attribute subscriber.
+
+        Args:
+           connection:
+             The connection of the subscriber.
+           attribute:
+             The attribute whose value is notified.
+           value:
+             The value of the attribute (if None, the value is read from the attribute)
+            force:
+              If True, send a notification even if there is no subscriber.
+        """
         await self.gatt_server.notify_subscriber(connection, attribute, value, force)
 
-    async def notify_subscribers(self, attribute, value=None, force=False):
+    async def notify_subscribers(
+        self, attribute: Attribute, value=None, force=False
+    ) -> None:
+        """
+        Send a notification to all the subscribers of an attribute.
+
+        Args:
+           attribute:
+             The attribute whose value is notified.
+           value:
+             The value of the attribute (if None, the value is read from the attribute)
+            force:
+              If True, send a notification for every connection even if there is no
+              subscriber.
+        """
         await self.gatt_server.notify_subscribers(attribute, value, force)
 
-    async def indicate_subscriber(self, connection, attribute, value=None, force=False):
+    async def indicate_subscriber(
+        self,
+        connection: Connection,
+        attribute: Attribute,
+        value: Optional[Any] = None,
+        force: bool = False,
+    ):
+        """
+        Send an indication to an attribute subscriber.
+
+        This method returns when the response to the indication has been received.
+
+        Args:
+           connection:
+             The connection of the subscriber.
+           attribute:
+             The attribute whose value is indicated.
+           value:
+             The value of the attribute (if None, the value is read from the attribute)
+            force:
+              If True, send an indication even if there is no subscriber.
+        """
         await self.gatt_server.indicate_subscriber(connection, attribute, value, force)
 
-    async def indicate_subscribers(self, attribute, value=None, force=False):
+    async def indicate_subscribers(
+        self, attribute: Attribute, value: Optional[Any] = None, force: bool = False
+    ):
+        """
+        Send an indication to all the subscribers of an attribute.
+
+        Args:
+           attribute:
+             The attribute whose value is notified.
+           value:
+             The value of the attribute (if None, the value is read from the attribute)
+            force:
+              If True, send an indication for every connection even if there is no
+              subscriber.
+        """
         await self.gatt_server.indicate_subscribers(attribute, value, force)
 
     @host_event_handler

bumble/gatt.py

@@ -27,28 +27,16 @@ import enum
 import functools
 import logging
 import struct
-from typing import (
+from typing import Iterable, List, Optional, Sequence, TypeVar, Union
-    Any,
-    Callable,
-    Dict,
-    Iterable,
-    List,
-    Optional,
-    Sequence,
-    SupportsBytes,
-    Type,
-    Union,
-    TYPE_CHECKING,
-)
 
 from bumble.colors import color
-from bumble.core import BaseBumbleError, InvalidOperationError, UUID
+from bumble.core import BaseBumbleError, UUID
 from bumble.att import Attribute, AttributeValue
-from bumble.utils import ByteSerializable
-
-if TYPE_CHECKING:
-    from bumble.gatt_client import AttributeProxy
 
+# -----------------------------------------------------------------------------
+# Typing
+# -----------------------------------------------------------------------------
+_T = TypeVar('_T')
 
 # -----------------------------------------------------------------------------
 # Logging
@@ -436,7 +424,7 @@ class IncludedServiceDeclaration(Attribute):
 
 
 # -----------------------------------------------------------------------------
-class Characteristic(Attribute):
+class Characteristic(Attribute[_T]):
     '''
     See Vol 3, Part G - 3.3 CHARACTERISTIC DEFINITION
     '''
@@ -499,7 +487,7 @@ class Characteristic(Attribute):
         uuid: Union[str, bytes, UUID],
         properties: Characteristic.Properties,
         permissions: Union[str, Attribute.Permissions],
-        value: Any = b'',
+        value: Union[AttributeValue[_T], _T, None] = None,
         descriptors: Sequence[Descriptor] = (),
     ):
         super().__init__(uuid, permissions, value)
@@ -559,217 +547,10 @@ class CharacteristicDeclaration(Attribute):
 
 
 # -----------------------------------------------------------------------------
-class CharacteristicValue(AttributeValue):
+class CharacteristicValue(AttributeValue[_T]):
     """Same as AttributeValue, for backward compatibility"""
 
 
-# -----------------------------------------------------------------------------
-class CharacteristicAdapter:
-    '''
-    An adapter that can adapt Characteristic and AttributeProxy objects
-    by wrapping their `read_value()` and `write_value()` methods with ones that
-    return/accept encoded/decoded values.
-
-    For proxies (i.e used by a GATT client), the adaptation is one where the return
-    value of `read_value()` is decoded and the value passed to `write_value()` is
-    encoded. The `subscribe()` method, is wrapped with one where the values are decoded
-    before being passed to the subscriber.
-
-    For local values (i.e hosted by a GATT server) the adaptation is one where the
-    return value of `read_value()` is encoded and the value passed to `write_value()`
-    is decoded.
-    '''
-
-    read_value: Callable
-    write_value: Callable
-
-    def __init__(self, characteristic: Union[Characteristic, AttributeProxy]):
-        self.wrapped_characteristic = characteristic
-        self.subscribers: Dict[Callable, Callable] = (
-            {}
-        )  # Map from subscriber to proxy subscriber
-
-        if isinstance(characteristic, Characteristic):
-            self.read_value = self.read_encoded_value
-            self.write_value = self.write_encoded_value
-        else:
-            self.read_value = self.read_decoded_value
-            self.write_value = self.write_decoded_value
-            self.subscribe = self.wrapped_subscribe
-            self.unsubscribe = self.wrapped_unsubscribe
-
-    def __getattr__(self, name):
-        return getattr(self.wrapped_characteristic, name)
-
-    def __setattr__(self, name, value):
-        if name in (
-            'wrapped_characteristic',
-            'subscribers',
-            'read_value',
-            'write_value',
-            'subscribe',
-            'unsubscribe',
-        ):
-            super().__setattr__(name, value)
-        else:
-            setattr(self.wrapped_characteristic, name, value)
-
-    async def read_encoded_value(self, connection):
-        return self.encode_value(
-            await self.wrapped_characteristic.read_value(connection)
-        )
-
-    async def write_encoded_value(self, connection, value):
-        return await self.wrapped_characteristic.write_value(
-            connection, self.decode_value(value)
-        )
-
-    async def read_decoded_value(self):
-        return self.decode_value(await self.wrapped_characteristic.read_value())
-
-    async def write_decoded_value(self, value, with_response=False):
-        return await self.wrapped_characteristic.write_value(
-            self.encode_value(value), with_response
-        )
-
-    def encode_value(self, value):
-        return value
-
-    def decode_value(self, value):
-        return value
-
-    def wrapped_subscribe(self, subscriber=None):
-        if subscriber is not None:
-            if subscriber in self.subscribers:
-                # We already have a proxy subscriber
-                subscriber = self.subscribers[subscriber]
-            else:
-                # Create and register a proxy that will decode the value
-                original_subscriber = subscriber
-
-                def on_change(value):
-                    original_subscriber(self.decode_value(value))
-
-                self.subscribers[subscriber] = on_change
-                subscriber = on_change
-
-        return self.wrapped_characteristic.subscribe(subscriber)
-
-    def wrapped_unsubscribe(self, subscriber=None):
-        if subscriber in self.subscribers:
-            subscriber = self.subscribers.pop(subscriber)
-
-        return self.wrapped_characteristic.unsubscribe(subscriber)
-
-    def __str__(self) -> str:
-        wrapped = str(self.wrapped_characteristic)
-        return f'{self.__class__.__name__}({wrapped})'
-
-
-# -----------------------------------------------------------------------------
-class DelegatedCharacteristicAdapter(CharacteristicAdapter):
-    '''
-    Adapter that converts bytes values using an encode and a decode function.
-    '''
-
-    def __init__(self, characteristic, encode=None, decode=None):
-        super().__init__(characteristic)
-        self.encode = encode
-        self.decode = decode
-
-    def encode_value(self, value):
-        if self.encode is None:
-            raise InvalidOperationError('delegated adapter does not have an encoder')
-        return self.encode(value)
-
-    def decode_value(self, value):
-        if self.decode is None:
-            raise InvalidOperationError('delegate adapter does not have a decoder')
-        return self.decode(value)
-
-
-# -----------------------------------------------------------------------------
-class PackedCharacteristicAdapter(CharacteristicAdapter):
-    '''
-    Adapter that packs/unpacks characteristic values according to a standard
-    Python `struct` format.
-    For formats with a single value, the adapted `read_value` and `write_value`
-    methods return/accept single values. For formats with multiple values,
-    they return/accept a tuple with the same number of elements as is required for
-    the format.
-    '''
-
-    def __init__(self, characteristic, pack_format):
-        super().__init__(characteristic)
-        self.struct = struct.Struct(pack_format)
-
-    def pack(self, *values):
-        return self.struct.pack(*values)
-
-    def unpack(self, buffer):
-        return self.struct.unpack(buffer)
-
-    def encode_value(self, value):
-        return self.pack(*value if isinstance(value, tuple) else (value,))
-
-    def decode_value(self, value):
-        unpacked = self.unpack(value)
-        return unpacked[0] if len(unpacked) == 1 else unpacked
-
-
-# -----------------------------------------------------------------------------
-class MappedCharacteristicAdapter(PackedCharacteristicAdapter):
-    '''
-    Adapter that packs/unpacks characteristic values according to a standard
-    Python `struct` format.
-    The adapted `read_value` and `write_value` methods return/accept a dictionary which
-    is packed/unpacked according to format, with the arguments extracted from the
-    dictionary by key, in the same order as they occur in the `keys` parameter.
-    '''
-
-    def __init__(self, characteristic, pack_format, keys):
-        super().__init__(characteristic, pack_format)
-        self.keys = keys
-
-    # pylint: disable=arguments-differ
-    def pack(self, values):
-        return super().pack(*(values[key] for key in self.keys))
-
-    def unpack(self, buffer):
-        return dict(zip(self.keys, super().unpack(buffer)))
-
-
-# -----------------------------------------------------------------------------
-class UTF8CharacteristicAdapter(CharacteristicAdapter):
-    '''
-    Adapter that converts strings to/from bytes using UTF-8 encoding
-    '''
-
-    def encode_value(self, value: str) -> bytes:
-        return value.encode('utf-8')
-
-    def decode_value(self, value: bytes) -> str:
-        return value.decode('utf-8')
-
-
-# -----------------------------------------------------------------------------
-class SerializableCharacteristicAdapter(CharacteristicAdapter):
-    '''
-    Adapter that converts any class to/from bytes using the class'
-    `to_bytes` and `__bytes__` methods, respectively.
-    '''
-
-    def __init__(self, characteristic, cls: Type[ByteSerializable]):
-        super().__init__(characteristic)
-        self.cls = cls
-
-    def encode_value(self, value: SupportsBytes) -> bytes:
-        return bytes(value)
-
-    def decode_value(self, value: bytes) -> Any:
-        return self.cls.from_bytes(value)
-
-
 # -----------------------------------------------------------------------------
 class Descriptor(Attribute):
     '''

bumble/gatt_adapters.py

@@ -0,0 +1,390 @@
+# Copyright 2025 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#      https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# -----------------------------------------------------------------------------
+# GATT - Type Adapters
+# -----------------------------------------------------------------------------
+
+# -----------------------------------------------------------------------------
+# Imports
+# -----------------------------------------------------------------------------
+from __future__ import annotations
+import struct
+from typing import (
+    Any,
+    Callable,
+    Generic,
+    Iterable,
+    Literal,
+    Optional,
+    Type,
+    TypeVar,
+)
+
+from bumble.core import InvalidOperationError
+from bumble.gatt import Characteristic
+from bumble.gatt_client import CharacteristicProxy
+from bumble.utils import ByteSerializable, IntConvertible
+
+
+# -----------------------------------------------------------------------------
+# Typing
+# -----------------------------------------------------------------------------
+_T = TypeVar('_T')
+_T2 = TypeVar('_T2', bound=ByteSerializable)
+_T3 = TypeVar('_T3', bound=IntConvertible)
+
+
+# -----------------------------------------------------------------------------
+class CharacteristicAdapter(Characteristic, Generic[_T]):
+    '''
+    An adapter that can adapt a Characteristic to automatically encode/decode values
+    read/written from the characteristic.
+    '''
+
+    def __init__(self, characteristic: Characteristic) -> None:
+        super().__init__(
+            characteristic.uuid,
+            characteristic.properties,
+            characteristic.permissions,
+            characteristic.value,
+            characteristic.descriptors,
+        )
+
+
+# -----------------------------------------------------------------------------
+class CharacteristicProxyAdapter(CharacteristicProxy[_T]):
+    '''
+    An adapter that can adapt Characteristic and AttributeProxy objects
+    by wrapping their `read_value()` and `write_value()` methods with ones that
+    return/accept encoded/decoded values.
+
+    For proxies (i.e used by a GATT client), the adaptation is one where the return
+    value of `read_value()` is decoded and the value passed to `write_value()` is
+    encoded. The `subscribe()` method, is wrapped with one where the values are decoded
+    before being passed to the subscriber.
+
+    For local values (i.e hosted by a GATT server) the adaptation is one where the
+    return value of `read_value()` is encoded and the value passed to `write_value()`
+    is decoded.
+    '''
+
+    def __init__(self, characteristic_proxy: CharacteristicProxy):
+        super().__init__(
+            characteristic_proxy.client,
+            characteristic_proxy.handle,
+            characteristic_proxy.end_group_handle,
+            characteristic_proxy.uuid,
+            characteristic_proxy.properties,
+        )
+
+
+# -----------------------------------------------------------------------------
+class DelegatedCharacteristicAdapter(CharacteristicAdapter[_T]):
+    '''
+    Adapter that converts bytes values using an encode and/or a decode function.
+    '''
+
+    def __init__(
+        self,
+        characteristic: Characteristic,
+        encode: Optional[Callable[[_T], bytes]] = None,
+        decode: Optional[Callable[[bytes], _T]] = None,
+    ):
+        super().__init__(characteristic)
+        self.encode = encode
+        self.decode = decode
+
+    def encode_value(self, value: _T) -> bytes:
+        if self.encode is None:
+            raise InvalidOperationError('delegated adapter does not have an encoder')
+        return self.encode(value)
+
+    def decode_value(self, value: bytes) -> _T:
+        if self.decode is None:
+            raise InvalidOperationError('delegate adapter does not have a decoder')
+        return self.decode(value)
+
+
+# -----------------------------------------------------------------------------
+class DelegatedCharacteristicProxyAdapter(CharacteristicProxyAdapter[_T]):
+    '''
+    Adapter that converts bytes values using an encode and a decode function.
+    '''
+
+    def __init__(
+        self,
+        characteristic_proxy: CharacteristicProxy,
+        encode: Optional[Callable[[_T], bytes]] = None,
+        decode: Optional[Callable[[bytes], _T]] = None,
+    ):
+        super().__init__(characteristic_proxy)
+        self.encode = encode
+        self.decode = decode
+
+    def encode_value(self, value: _T) -> bytes:
+        if self.encode is None:
+            raise InvalidOperationError('delegated adapter does not have an encoder')
+        return self.encode(value)
+
+    def decode_value(self, value: bytes) -> _T:
+        if self.decode is None:
+            raise InvalidOperationError('delegate adapter does not have a decoder')
+        return self.decode(value)
+
+
+# -----------------------------------------------------------------------------
+class PackedCharacteristicAdapter(CharacteristicAdapter):
+    '''
+    Adapter that packs/unpacks characteristic values according to a standard
+    Python `struct` format.
+    For formats with a single value, the adapted `read_value` and `write_value`
+    methods return/accept single values. For formats with multiple values,
+    they return/accept a tuple with the same number of elements as is required for
+    the format.
+    '''
+
+    def __init__(self, characteristic: Characteristic, pack_format: str) -> None:
+        super().__init__(characteristic)
+        self.struct = struct.Struct(pack_format)
+
+    def pack(self, *values) -> bytes:
+        return self.struct.pack(*values)
+
+    def unpack(self, buffer: bytes) -> tuple:
+        return self.struct.unpack(buffer)
+
+    def encode_value(self, value: Any) -> bytes:
+        return self.pack(*value if isinstance(value, tuple) else (value,))
+
+    def decode_value(self, value: bytes) -> Any:
+        unpacked = self.unpack(value)
+        return unpacked[0] if len(unpacked) == 1 else unpacked
+
+
+# -----------------------------------------------------------------------------
+class PackedCharacteristicProxyAdapter(CharacteristicProxyAdapter):
+    '''
+    Adapter that packs/unpacks characteristic values according to a standard
+    Python `struct` format.
+    For formats with a single value, the adapted `read_value` and `write_value`
+    methods return/accept single values. For formats with multiple values,
+    they return/accept a tuple with the same number of elements as is required for
+    the format.
+    '''
+
+    def __init__(self, characteristic_proxy, pack_format):
+        super().__init__(characteristic_proxy)
+        self.struct = struct.Struct(pack_format)
+
+    def pack(self, *values) -> bytes:
+        return self.struct.pack(*values)
+
+    def unpack(self, buffer: bytes) -> tuple:
+        return self.struct.unpack(buffer)
+
+    def encode_value(self, value: Any) -> bytes:
+        return self.pack(*value if isinstance(value, tuple) else (value,))
+
+    def decode_value(self, value: bytes) -> Any:
+        unpacked = self.unpack(value)
+        return unpacked[0] if len(unpacked) == 1 else unpacked
+
+
+# -----------------------------------------------------------------------------
+class MappedCharacteristicAdapter(PackedCharacteristicAdapter):
+    '''
+    Adapter that packs/unpacks characteristic values according to a standard
+    Python `struct` format.
+    The adapted `read_value` and `write_value` methods return/accept a dictionary which
+    is packed/unpacked according to format, with the arguments extracted from the
+    dictionary by key, in the same order as they occur in the `keys` parameter.
+    '''
+
+    def __init__(
+        self, characteristic: Characteristic, pack_format: str, keys: Iterable[str]
+    ) -> None:
+        super().__init__(characteristic, pack_format)
+        self.keys = keys
+
+    # pylint: disable=arguments-differ
+    def pack(self, values) -> bytes:
+        return super().pack(*(values[key] for key in self.keys))
+
+    def unpack(self, buffer: bytes) -> Any:
+        return dict(zip(self.keys, super().unpack(buffer)))
+
+
+# -----------------------------------------------------------------------------
+class MappedCharacteristicProxyAdapter(PackedCharacteristicProxyAdapter):
+    '''
+    Adapter that packs/unpacks characteristic values according to a standard
+    Python `struct` format.
+    The adapted `read_value` and `write_value` methods return/accept a dictionary which
+    is packed/unpacked according to format, with the arguments extracted from the
+    dictionary by key, in the same order as they occur in the `keys` parameter.
+    '''
+
+    def __init__(
+        self,
+        characteristic_proxy: CharacteristicProxy,
+        pack_format: str,
+        keys: Iterable[str],
+    ) -> None:
+        super().__init__(characteristic_proxy, pack_format)
+        self.keys = keys
+
+    # pylint: disable=arguments-differ
+    def pack(self, values) -> bytes:
+        return super().pack(*(values[key] for key in self.keys))
+
+    def unpack(self, buffer: bytes) -> Any:
+        return dict(zip(self.keys, super().unpack(buffer)))
+
+
+# -----------------------------------------------------------------------------
+class UTF8CharacteristicAdapter(CharacteristicAdapter[str]):
+    '''
+    Adapter that converts strings to/from bytes using UTF-8 encoding
+    '''
+
+    def encode_value(self, value: str) -> bytes:
+        return value.encode('utf-8')
+
+    def decode_value(self, value: bytes) -> str:
+        return value.decode('utf-8')
+
+
+# -----------------------------------------------------------------------------
+class UTF8CharacteristicProxyAdapter(CharacteristicProxyAdapter[str]):
+    '''
+    Adapter that converts strings to/from bytes using UTF-8 encoding
+    '''
+
+    def encode_value(self, value: str) -> bytes:
+        return value.encode('utf-8')
+
+    def decode_value(self, value: bytes) -> str:
+        return value.decode('utf-8')
+
+
+# -----------------------------------------------------------------------------
+class SerializableCharacteristicAdapter(CharacteristicAdapter[_T2]):
+    '''
+    Adapter that converts any class to/from bytes using the class'
+    `to_bytes` and `__bytes__` methods, respectively.
+    '''
+
+    def __init__(self, characteristic: Characteristic, cls: Type[_T2]) -> None:
+        super().__init__(characteristic)
+        self.cls = cls
+
+    def encode_value(self, value: _T2) -> bytes:
+        return bytes(value)
+
+    def decode_value(self, value: bytes) -> _T2:
+        return self.cls.from_bytes(value)
+
+
+# -----------------------------------------------------------------------------
+class SerializableCharacteristicProxyAdapter(CharacteristicProxyAdapter[_T2]):
+    '''
+    Adapter that converts any class to/from bytes using the class'
+    `to_bytes` and `__bytes__` methods, respectively.
+    '''
+
+    def __init__(
+        self, characteristic_proxy: CharacteristicProxy, cls: Type[_T2]
+    ) -> None:
+        super().__init__(characteristic_proxy)
+        self.cls = cls
+
+    def encode_value(self, value: _T2) -> bytes:
+        return bytes(value)
+
+    def decode_value(self, value: bytes) -> _T2:
+        return self.cls.from_bytes(value)
+
+
+# -----------------------------------------------------------------------------
+class EnumCharacteristicAdapter(CharacteristicAdapter[_T3]):
+    '''
+    Adapter that converts int-enum-like classes to/from bytes using the class'
+    `int().to_bytes()` and `from_bytes()` methods, respectively.
+    '''
+
+    def __init__(
+        self,
+        characteristic: Characteristic,
+        cls: Type[_T3],
+        length: int,
+        byteorder: Literal['little', 'big'] = 'little',
+    ):
+        """
+        Initialize an instance.
+
+        Params:
+          characteristic: the Characteristic to adapt to/from
+          cls: the class to/from which to convert integer values
+          length: number of bytes used to represent integer values
+          byteorder: byte order of the byte representation of integers.
+        """
+        super().__init__(characteristic)
+        self.cls = cls
+        self.length = length
+        self.byteorder = byteorder
+
+    def encode_value(self, value: _T3) -> bytes:
+        return int(value).to_bytes(self.length, self.byteorder)
+
+    def decode_value(self, value: bytes) -> _T3:
+        int_value = int.from_bytes(value, self.byteorder)
+        return self.cls(int_value)
+
+
+# -----------------------------------------------------------------------------
+class EnumCharacteristicProxyAdapter(CharacteristicProxyAdapter[_T3]):
+    '''
+    Adapter that converts int-enum-like classes to/from bytes using the class'
+    `int().to_bytes()` and `from_bytes()` methods, respectively.
+    '''
+
+    def __init__(
+        self,
+        characteristic_proxy: CharacteristicProxy,
+        cls: Type[_T3],
+        length: int,
+        byteorder: Literal['little', 'big'] = 'little',
+    ):
+        """
+        Initialize an instance.
+
+        Params:
+          characteristic_proxy: the CharacteristicProxy to adapt to/from
+          cls: the class to/from which to convert integer values
+          length: number of bytes used to represent integer values
+          byteorder: byte order of the byte representation of integers.
+        """
+        super().__init__(characteristic_proxy)
+        self.cls = cls
+        self.length = length
+        self.byteorder = byteorder
+
+    def encode_value(self, value: _T3) -> bytes:
+        return int(value).to_bytes(self.length, self.byteorder)
+
+    def decode_value(self, value: bytes) -> _T3:
+        int_value = int.from_bytes(value, self.byteorder)
+        a = self.cls(int_value)
+        return self.cls(int_value)

bumble/gatt_client.py

@@ -29,16 +29,18 @@ import logging
 import struct
 from datetime import datetime
 from typing import (
+    Any,
+    Callable,
+    Dict,
+    Generic,
+    Iterable,
     List,
     Optional,
-    Dict,
-    Tuple,
-    Callable,
-    Union,
-    Any,
-    Iterable,
-    Type,
     Set,
+    Tuple,
+    Union,
+    Type,
+    TypeVar,
     TYPE_CHECKING,
 )
 
@@ -82,9 +84,14 @@ from .gatt import (
     TemplateService,
 )
 
+# -----------------------------------------------------------------------------
+# Typing
+# -----------------------------------------------------------------------------
 if TYPE_CHECKING:
     from bumble.device import Connection
 
+_T = TypeVar('_T')
+
 # -----------------------------------------------------------------------------
 # Logging
 # -----------------------------------------------------------------------------
@@ -110,7 +117,7 @@ def show_services(services: Iterable[ServiceProxy]) -> None:
 # -----------------------------------------------------------------------------
 # Proxies
 # -----------------------------------------------------------------------------
-class AttributeProxy(EventEmitter):
+class AttributeProxy(EventEmitter, Generic[_T]):
     def __init__(
         self, client: Client, handle: int, end_group_handle: int, attribute_type: UUID
     ) -> None:
@@ -120,21 +127,21 @@ class AttributeProxy(EventEmitter):
         self.end_group_handle = end_group_handle
         self.type = attribute_type
 
-    async def read_value(self, no_long_read: bool = False) -> bytes:
+    async def read_value(self, no_long_read: bool = False) -> _T:
         return self.decode_value(
             await self.client.read_value(self.handle, no_long_read)
         )
 
-    async def write_value(self, value, with_response=False):
+    async def write_value(self, value: _T, with_response=False):
         return await self.client.write_value(
             self.handle, self.encode_value(value), with_response
         )
 
-    def encode_value(self, value: Any) -> bytes:
+    def encode_value(self, value: _T) -> bytes:
-        return value
+        return value  # type: ignore
 
-    def decode_value(self, value_bytes: bytes) -> Any:
+    def decode_value(self, value: bytes) -> _T:
-        return value_bytes
+        return value  # type: ignore
 
     def __str__(self) -> str:
         return f'Attribute(handle=0x{self.handle:04X}, type={self.type})'
@@ -184,19 +191,19 @@ class ServiceProxy(AttributeProxy):
         return f'Service(handle=0x{self.handle:04X}, uuid={self.uuid})'
 
 
-class CharacteristicProxy(AttributeProxy):
+class CharacteristicProxy(AttributeProxy[_T]):
     properties: Characteristic.Properties
     descriptors: List[DescriptorProxy]
-    subscribers: Dict[Any, Callable[[bytes], Any]]
+    subscribers: Dict[Any, Callable[[_T], Any]]
 
     def __init__(
         self,
-        client,
+        client: Client,
-        handle,
+        handle: int,
-        end_group_handle,
+        end_group_handle: int,
-        uuid,
+        uuid: UUID,
         properties: int,
-    ):
+    ) -> None:
         super().__init__(client, handle, end_group_handle, uuid)
         self.uuid = uuid
         self.properties = Characteristic.Properties(properties)
@@ -204,21 +211,21 @@ class CharacteristicProxy(AttributeProxy):
         self.descriptors_discovered = False
         self.subscribers = {}  # Map from subscriber to proxy subscriber
 
-    def get_descriptor(self, descriptor_type):
+    def get_descriptor(self, descriptor_type: UUID) -> Optional[DescriptorProxy]:
         for descriptor in self.descriptors:
             if descriptor.type == descriptor_type:
                 return descriptor
 
         return None
 
-    async def discover_descriptors(self):
+    async def discover_descriptors(self) -> list[DescriptorProxy]:
         return await self.client.discover_descriptors(self)
 
     async def subscribe(
         self,
-        subscriber: Optional[Callable[[bytes], Any]] = None,
+        subscriber: Optional[Callable[[_T], Any]] = None,
         prefer_notify: bool = True,
-    ):
+    ) -> None:
         if subscriber is not None:
             if subscriber in self.subscribers:
                 # We already have a proxy subscriber
@@ -233,13 +240,13 @@ class CharacteristicProxy(AttributeProxy):
                 self.subscribers[subscriber] = on_change
                 subscriber = on_change
 
-        return await self.client.subscribe(self, subscriber, prefer_notify)
+        await self.client.subscribe(self, subscriber, prefer_notify)
 
-    async def unsubscribe(self, subscriber=None, force=False):
+    async def unsubscribe(self, subscriber=None, force=False) -> None:
         if subscriber in self.subscribers:
             subscriber = self.subscribers.pop(subscriber)
 
-        return await self.client.unsubscribe(self, subscriber, force)
+        await self.client.unsubscribe(self, subscriber, force)
 
     def __str__(self) -> str:
         return (
@@ -250,7 +257,7 @@ class CharacteristicProxy(AttributeProxy):
 
 
 class DescriptorProxy(AttributeProxy):
-    def __init__(self, client, handle, descriptor_type):
+    def __init__(self, client: Client, handle: int, descriptor_type: UUID) -> None:
         super().__init__(client, handle, 0, descriptor_type)
 
     def __str__(self) -> str:
@@ -679,7 +686,7 @@ class Client:
 
                     properties, handle = struct.unpack_from('<BH', attribute_value)
                     characteristic_uuid = UUID.from_bytes(attribute_value[3:])
-                    characteristic = CharacteristicProxy(
+                    characteristic: CharacteristicProxy = CharacteristicProxy(
                         self, handle, 0, characteristic_uuid, properties
                     )
 
@@ -805,7 +812,7 @@ class Client:
                     logger.warning(f'bogus handle value: {attribute_handle}')
                     return []
 
-                attribute = AttributeProxy(
+                attribute: AttributeProxy = AttributeProxy(
                     self, attribute_handle, 0, UUID.from_bytes(attribute_uuid)
                 )
                 attributes.append(attribute)
@@ -818,7 +825,7 @@ class Client:
     async def subscribe(
         self,
         characteristic: CharacteristicProxy,
-        subscriber: Optional[Callable[[bytes], Any]] = None,
+        subscriber: Optional[Callable[[Any], Any]] = None,
         prefer_notify: bool = True,
     ) -> None:
         # If we haven't already discovered the descriptors for this characteristic,
@@ -868,7 +875,7 @@ class Client:
     async def unsubscribe(
         self,
         characteristic: CharacteristicProxy,
-        subscriber: Optional[Callable[[bytes], Any]] = None,
+        subscriber: Optional[Callable[[Any], Any]] = None,
         force: bool = False,
     ) -> None:
         '''

bumble/gatt_server.py

@@ -36,7 +36,6 @@ from typing import (
     Tuple,
     TypeVar,
     Type,
-    Union,
     TYPE_CHECKING,
 )
 from pyee import EventEmitter
@@ -78,7 +77,6 @@ from bumble.gatt import (
     GATT_REQUEST_TIMEOUT,
     GATT_SECONDARY_SERVICE_ATTRIBUTE_TYPE,
     Characteristic,
-    CharacteristicAdapter,
     CharacteristicDeclaration,
     CharacteristicValue,
     IncludedServiceDeclaration,
@@ -469,7 +467,7 @@ class Server(EventEmitter):
             finally:
                 self.pending_confirmations[connection.handle] = None
 
-    async def notify_or_indicate_subscribers(
+    async def _notify_or_indicate_subscribers(
         self,
         indicate: bool,
         attribute: Attribute,
@@ -503,7 +501,9 @@ class Server(EventEmitter):
         value: Optional[bytes] = None,
         force: bool = False,
     ):
-        return await self.notify_or_indicate_subscribers(False, attribute, value, force)
+        return await self._notify_or_indicate_subscribers(
+            False, attribute, value, force
+        )
 
     async def indicate_subscribers(
         self,
@@ -511,7 +511,7 @@ class Server(EventEmitter):
         value: Optional[bytes] = None,
         force: bool = False,
     ):
-        return await self.notify_or_indicate_subscribers(True, attribute, value, force)
+        return await self._notify_or_indicate_subscribers(True, attribute, value, force)
 
     def on_disconnection(self, connection: Connection) -> None:
         if connection.handle in self.subscribers:

bumble/profiles/aics.py

@@ -24,16 +24,13 @@ import struct
 from dataclasses import dataclass
 from typing import Optional
 
-from bumble import gatt
 from bumble.device import Connection
 from bumble.att import ATT_Error
 from bumble.gatt import (
+    Attribute,
     Characteristic,
-    SerializableCharacteristicAdapter,
-    PackedCharacteristicAdapter,
     TemplateService,
     CharacteristicValue,
-    UTF8CharacteristicAdapter,
     GATT_AUDIO_INPUT_CONTROL_SERVICE,
     GATT_AUDIO_INPUT_STATE_CHARACTERISTIC,
     GATT_GAIN_SETTINGS_ATTRIBUTE_CHARACTERISTIC,
@@ -42,6 +39,14 @@ from bumble.gatt import (
     GATT_AUDIO_INPUT_CONTROL_POINT_CHARACTERISTIC,
     GATT_AUDIO_INPUT_DESCRIPTION_CHARACTERISTIC,
 )
+from bumble.gatt_adapters import (
+    CharacteristicProxy,
+    PackedCharacteristicProxyAdapter,
+    SerializableCharacteristicAdapter,
+    SerializableCharacteristicProxyAdapter,
+    UTF8CharacteristicAdapter,
+    UTF8CharacteristicProxyAdapter,
+)
 from bumble.gatt_client import ProfileServiceProxy, ServiceProxy
 from bumble.utils import OpenIntEnum
 
@@ -124,7 +129,7 @@ class AudioInputState:
     mute: Mute = Mute.NOT_MUTED
     gain_mode: GainMode = GainMode.MANUAL
     change_counter: int = 0
-    attribute_value: Optional[CharacteristicValue] = None
+    attribute: Optional[Attribute] = None
 
     def __bytes__(self) -> bytes:
         return bytes(
@@ -151,10 +156,8 @@ class AudioInputState:
         self.change_counter = (self.change_counter + 1) % (CHANGE_COUNTER_MAX_VALUE + 1)
 
     async def notify_subscribers_via_connection(self, connection: Connection) -> None:
-        assert self.attribute_value is not None
+        assert self.attribute is not None
-        await connection.device.notify_subscribers(
+        await connection.device.notify_subscribers(attribute=self.attribute)
-            attribute=self.attribute_value, value=bytes(self)
-        )
 
 
 @dataclass
@@ -315,24 +318,28 @@ class AudioInputDescription:
     '''
 
     audio_input_description: str = "Bluetooth"
-    attribute_value: Optional[CharacteristicValue] = None
+    attribute: Optional[Attribute] = None
 
     def on_read(self, _connection: Optional[Connection]) -> str:
         return self.audio_input_description
 
     async def on_write(self, connection: Optional[Connection], value: str) -> None:
         assert connection
-        assert self.attribute_value
+        assert self.attribute
 
         self.audio_input_description = value
-        await connection.device.notify_subscribers(
+        await connection.device.notify_subscribers(attribute=self.attribute)
-            attribute=self.attribute_value, value=value
-        )
 
 
 class AICSService(TemplateService):
     UUID = GATT_AUDIO_INPUT_CONTROL_SERVICE
 
+    audio_input_state_characteristic: Characteristic[AudioInputState]
+    audio_input_type_characteristic: Characteristic[bytes]
+    audio_input_status_characteristic: Characteristic[bytes]
+    audio_input_control_point_characteristic: Characteristic[bytes]
+    gain_settings_properties_characteristic: Characteristic[GainSettingsProperties]
+
     def __init__(
         self,
         audio_input_state: Optional[AudioInputState] = None,
@@ -374,9 +381,7 @@ class AICSService(TemplateService):
             ),
             AudioInputState,
         )
-        self.audio_input_state.attribute_value = (
+        self.audio_input_state.attribute = self.audio_input_state_characteristic
-            self.audio_input_state_characteristic.value
-        )
 
         self.gain_settings_properties_characteristic = (
             SerializableCharacteristicAdapter(
@@ -425,8 +430,8 @@ class AICSService(TemplateService):
                 ),
             )
         )
-        self.audio_input_description.attribute_value = (
+        self.audio_input_description.attribute = (
-            self.audio_input_control_point_characteristic.value
+            self.audio_input_control_point_characteristic
         )
 
         super().__init__(
@@ -448,24 +453,29 @@ class AICSService(TemplateService):
 class AICSServiceProxy(ProfileServiceProxy):
     SERVICE_CLASS = AICSService
 
+    audio_input_state: CharacteristicProxy[AudioInputState]
+    gain_settings_properties: CharacteristicProxy[GainSettingsProperties]
+    audio_input_status: CharacteristicProxy[int]
+    audio_input_control_point: CharacteristicProxy[bytes]
+
     def __init__(self, service_proxy: ServiceProxy) -> None:
         self.service_proxy = service_proxy
 
-        self.audio_input_state = SerializableCharacteristicAdapter(
+        self.audio_input_state = SerializableCharacteristicProxyAdapter(
             service_proxy.get_required_characteristic_by_uuid(
                 GATT_AUDIO_INPUT_STATE_CHARACTERISTIC
             ),
             AudioInputState,
         )
 
-        self.gain_settings_properties = SerializableCharacteristicAdapter(
+        self.gain_settings_properties = SerializableCharacteristicProxyAdapter(
             service_proxy.get_required_characteristic_by_uuid(
                 GATT_GAIN_SETTINGS_ATTRIBUTE_CHARACTERISTIC
             ),
             GainSettingsProperties,
         )
 
-        self.audio_input_status = PackedCharacteristicAdapter(
+        self.audio_input_status = PackedCharacteristicProxyAdapter(
             service_proxy.get_required_characteristic_by_uuid(
                 GATT_AUDIO_INPUT_STATUS_CHARACTERISTIC
             ),
@@ -478,7 +488,7 @@ class AICSServiceProxy(ProfileServiceProxy):
             )
         )
 
-        self.audio_input_description = UTF8CharacteristicAdapter(
+        self.audio_input_description = UTF8CharacteristicProxyAdapter(
             service_proxy.get_required_characteristic_by_uuid(
                 GATT_AUDIO_INPUT_DESCRIPTION_CHARACTERISTIC
             )

bumble/profiles/asha.py

@@ -134,12 +134,14 @@ class AshaService(gatt.TemplateService):
             ),
         )
 
-        self.audio_control_point_characteristic = gatt.Characteristic(
+        self.audio_control_point_characteristic: gatt.Characteristic[bytes] = (
-            gatt.GATT_ASHA_AUDIO_CONTROL_POINT_CHARACTERISTIC,
+            gatt.Characteristic(
-            gatt.Characteristic.Properties.WRITE
+                gatt.GATT_ASHA_AUDIO_CONTROL_POINT_CHARACTERISTIC,
-            | gatt.Characteristic.Properties.WRITE_WITHOUT_RESPONSE,
+                gatt.Characteristic.Properties.WRITE
-            gatt.Characteristic.WRITEABLE,
+                | gatt.Characteristic.Properties.WRITE_WITHOUT_RESPONSE,
-            gatt.CharacteristicValue(write=self._on_audio_control_point_write),
+                gatt.Characteristic.WRITEABLE,
+                gatt.CharacteristicValue(write=self._on_audio_control_point_write),
+            )
         )
         self.audio_status_characteristic = gatt.Characteristic(
             gatt.GATT_ASHA_AUDIO_STATUS_CHARACTERISTIC,
@@ -147,7 +149,7 @@ class AshaService(gatt.TemplateService):
             gatt.Characteristic.READABLE,
             bytes([AudioStatus.OK]),
         )
-        self.volume_characteristic = gatt.Characteristic(
+        self.volume_characteristic: gatt.Characteristic[bytes] = gatt.Characteristic(
             gatt.GATT_ASHA_VOLUME_CHARACTERISTIC,
             gatt.Characteristic.Properties.WRITE_WITHOUT_RESPONSE,
             gatt.Characteristic.WRITEABLE,
@@ -166,13 +168,13 @@ class AshaService(gatt.TemplateService):
             struct.pack('<H', self.psm),
         )
 
-        characteristics = [
+        characteristics = (
             self.read_only_properties_characteristic,
             self.audio_control_point_characteristic,
             self.audio_status_characteristic,
             self.volume_characteristic,
             self.le_psm_out_characteristic,
-        ]
+        )
 
         super().__init__(characteristics)
 

bumble/profiles/bass.py

@@ -20,11 +20,12 @@ from __future__ import annotations
 import dataclasses
 import logging
 import struct
-from typing import ClassVar, List, Optional, Sequence
+from typing import ClassVar, Optional, Sequence
 
 from bumble import core
 from bumble import device
 from bumble import gatt
+from bumble import gatt_adapters
 from bumble import gatt_client
 from bumble import hci
 from bumble import utils
@@ -52,7 +53,7 @@ def encode_subgroups(subgroups: Sequence[SubgroupInfo]) -> bytes:
     )
 
 
-def decode_subgroups(data: bytes) -> List[SubgroupInfo]:
+def decode_subgroups(data: bytes) -> list[SubgroupInfo]:
     num_subgroups = data[0]
     offset = 1
     subgroups = []
@@ -273,7 +274,7 @@ class BroadcastReceiveState:
     pa_sync_state: PeriodicAdvertisingSyncState
     big_encryption: BigEncryption
     bad_code: bytes
-    subgroups: List[SubgroupInfo]
+    subgroups: list[SubgroupInfo]
 
     @classmethod
     def from_bytes(cls, data: bytes) -> BroadcastReceiveState:
@@ -354,7 +355,9 @@ class BroadcastAudioScanServiceProxy(gatt_client.ProfileServiceProxy):
     SERVICE_CLASS = BroadcastAudioScanService
 
     broadcast_audio_scan_control_point: gatt_client.CharacteristicProxy
-    broadcast_receive_states: List[gatt.DelegatedCharacteristicAdapter]
+    broadcast_receive_states: list[
+        gatt_client.CharacteristicProxy[Optional[BroadcastReceiveState]]
+    ]
 
     def __init__(self, service_proxy: gatt_client.ServiceProxy):
         self.service_proxy = service_proxy
@@ -366,7 +369,7 @@ class BroadcastAudioScanServiceProxy(gatt_client.ProfileServiceProxy):
         )
 
         self.broadcast_receive_states = [
-            gatt.DelegatedCharacteristicAdapter(
+            gatt_adapters.DelegatedCharacteristicProxyAdapter(
                 characteristic,
                 decode=lambda x: BroadcastReceiveState.from_bytes(x) if x else None,
             )

bumble/profiles/battery_service.py

@@ -16,14 +16,20 @@
 # -----------------------------------------------------------------------------
 # Imports
 # -----------------------------------------------------------------------------
-from ..gatt_client import ProfileServiceProxy
+from typing import Optional
-from ..gatt import (
+
+from bumble.gatt_client import ProfileServiceProxy
+from bumble.gatt import (
     GATT_BATTERY_SERVICE,
     GATT_BATTERY_LEVEL_CHARACTERISTIC,
     TemplateService,
     Characteristic,
     CharacteristicValue,
+)
+from bumble.gatt_client import CharacteristicProxy
+from bumble.gatt_adapters import (
     PackedCharacteristicAdapter,
+    PackedCharacteristicProxyAdapter,
 )
 
 
@@ -32,6 +38,8 @@ class BatteryService(TemplateService):
     UUID = GATT_BATTERY_SERVICE
     BATTERY_LEVEL_FORMAT = 'B'
 
+    battery_level_characteristic: Characteristic[int]
+
     def __init__(self, read_battery_level):
         self.battery_level_characteristic = PackedCharacteristicAdapter(
             Characteristic(
@@ -49,13 +57,15 @@ class BatteryService(TemplateService):
 class BatteryServiceProxy(ProfileServiceProxy):
     SERVICE_CLASS = BatteryService
 
+    battery_level: Optional[CharacteristicProxy[int]]
+
     def __init__(self, service_proxy):
         self.service_proxy = service_proxy
 
         if characteristics := service_proxy.get_characteristics_by_uuid(
             GATT_BATTERY_LEVEL_CHARACTERISTIC
         ):
-            self.battery_level = PackedCharacteristicAdapter(
+            self.battery_level = PackedCharacteristicProxyAdapter(
                 characteristics[0], pack_format=BatteryService.BATTERY_LEVEL_FORMAT
             )
         else:

bumble/profiles/device_information_service.py

@@ -19,7 +19,6 @@
 import struct
 from typing import Optional, Tuple
 
-from bumble.gatt_client import ServiceProxy, ProfileServiceProxy, CharacteristicProxy
 from bumble.gatt import (
     GATT_DEVICE_INFORMATION_SERVICE,
     GATT_FIRMWARE_REVISION_STRING_CHARACTERISTIC,
@@ -32,9 +31,12 @@ from bumble.gatt import (
     GATT_REGULATORY_CERTIFICATION_DATA_LIST_CHARACTERISTIC,
     TemplateService,
     Characteristic,
-    DelegatedCharacteristicAdapter,
-    UTF8CharacteristicAdapter,
 )
+from bumble.gatt_adapters import (
+    DelegatedCharacteristicProxyAdapter,
+    UTF8CharacteristicProxyAdapter,
+)
+from bumble.gatt_client import CharacteristicProxy, ProfileServiceProxy, ServiceProxy
 
 
 # -----------------------------------------------------------------------------
@@ -62,7 +64,7 @@ class DeviceInformationService(TemplateService):
         ieee_regulatory_certification_data_list: Optional[bytes] = None,
         # TODO: pnp_id
     ):
-        characteristics = [
+        characteristics: list[Characteristic[bytes]] = [
             Characteristic(
                 uuid,
                 Characteristic.Properties.READ,
@@ -107,14 +109,14 @@ class DeviceInformationService(TemplateService):
 class DeviceInformationServiceProxy(ProfileServiceProxy):
     SERVICE_CLASS = DeviceInformationService
 
-    manufacturer_name: Optional[UTF8CharacteristicAdapter]
+    manufacturer_name: Optional[CharacteristicProxy[str]]
-    model_number: Optional[UTF8CharacteristicAdapter]
+    model_number: Optional[CharacteristicProxy[str]]
-    serial_number: Optional[UTF8CharacteristicAdapter]
+    serial_number: Optional[CharacteristicProxy[str]]
-    hardware_revision: Optional[UTF8CharacteristicAdapter]
+    hardware_revision: Optional[CharacteristicProxy[str]]
-    firmware_revision: Optional[UTF8CharacteristicAdapter]
+    firmware_revision: Optional[CharacteristicProxy[str]]
-    software_revision: Optional[UTF8CharacteristicAdapter]
+    software_revision: Optional[CharacteristicProxy[str]]
-    system_id: Optional[DelegatedCharacteristicAdapter]
+    system_id: Optional[CharacteristicProxy[tuple[int, int]]]
-    ieee_regulatory_certification_data_list: Optional[CharacteristicProxy]
+    ieee_regulatory_certification_data_list: Optional[CharacteristicProxy[bytes]]
 
     def __init__(self, service_proxy: ServiceProxy):
         self.service_proxy = service_proxy
@@ -128,7 +130,7 @@ class DeviceInformationServiceProxy(ProfileServiceProxy):
             ('software_revision', GATT_SOFTWARE_REVISION_STRING_CHARACTERISTIC),
         ):
             if characteristics := service_proxy.get_characteristics_by_uuid(uuid):
-                characteristic = UTF8CharacteristicAdapter(characteristics[0])
+                characteristic = UTF8CharacteristicProxyAdapter(characteristics[0])
             else:
                 characteristic = None
             self.__setattr__(field, characteristic)
@@ -136,7 +138,7 @@ class DeviceInformationServiceProxy(ProfileServiceProxy):
         if characteristics := service_proxy.get_characteristics_by_uuid(
             GATT_SYSTEM_ID_CHARACTERISTIC
         ):
-            self.system_id = DelegatedCharacteristicAdapter(
+            self.system_id = DelegatedCharacteristicProxyAdapter(
                 characteristics[0],
                 encode=lambda v: DeviceInformationService.pack_system_id(*v),
                 decode=DeviceInformationService.unpack_system_id,

bumble/profiles/gap.py

@@ -25,14 +25,15 @@ from bumble.core import Appearance
 from bumble.gatt import (
     TemplateService,
     Characteristic,
-    CharacteristicAdapter,
-    DelegatedCharacteristicAdapter,
-    UTF8CharacteristicAdapter,
     GATT_GENERIC_ACCESS_SERVICE,
     GATT_DEVICE_NAME_CHARACTERISTIC,
     GATT_APPEARANCE_CHARACTERISTIC,
 )
-from bumble.gatt_client import ProfileServiceProxy, ServiceProxy
+from bumble.gatt_adapters import (
+    DelegatedCharacteristicProxyAdapter,
+    UTF8CharacteristicProxyAdapter,
+)
+from bumble.gatt_client import CharacteristicProxy, ProfileServiceProxy, ServiceProxy
 
 # -----------------------------------------------------------------------------
 # Logging
@@ -49,6 +50,9 @@ logger = logging.getLogger(__name__)
 class GenericAccessService(TemplateService):
     UUID = GATT_GENERIC_ACCESS_SERVICE
 
+    device_name_characteristic: Characteristic[bytes]
+    appearance_characteristic: Characteristic[bytes]
+
     def __init__(
         self, device_name: str, appearance: Union[Appearance, Tuple[int, int], int] = 0
     ):
@@ -84,8 +88,8 @@ class GenericAccessService(TemplateService):
 class GenericAccessServiceProxy(ProfileServiceProxy):
     SERVICE_CLASS = GenericAccessService
 
-    device_name: Optional[CharacteristicAdapter]
+    device_name: Optional[CharacteristicProxy[str]]
-    appearance: Optional[DelegatedCharacteristicAdapter]
+    appearance: Optional[CharacteristicProxy[Appearance]]
 
     def __init__(self, service_proxy: ServiceProxy):
         self.service_proxy = service_proxy
@@ -93,14 +97,14 @@ class GenericAccessServiceProxy(ProfileServiceProxy):
         if characteristics := service_proxy.get_characteristics_by_uuid(
             GATT_DEVICE_NAME_CHARACTERISTIC
         ):
-            self.device_name = UTF8CharacteristicAdapter(characteristics[0])
+            self.device_name = UTF8CharacteristicProxyAdapter(characteristics[0])
         else:
             self.device_name = None
 
         if characteristics := service_proxy.get_characteristics_by_uuid(
             GATT_APPEARANCE_CHARACTERISTIC
         ):
-            self.appearance = DelegatedCharacteristicAdapter(
+            self.appearance = DelegatedCharacteristicProxyAdapter(
                 characteristics[0],
                 decode=lambda value: Appearance.from_int(
                     struct.unpack_from('<H', value, 0)[0],

bumble/profiles/gatt_service.py

@@ -110,6 +110,7 @@ class GenericAttributeProfileService(gatt.TemplateService):
             gatt.GATT_CHARACTERISTIC_ATTRIBUTE_TYPE,
             gatt.GATT_CHARACTERISTIC_EXTENDED_PROPERTIES_DESCRIPTOR,
         ):
+            assert isinstance(attribute.value, bytes)
             return (
                 struct.pack("<H", attribute.handle)
                 + attribute.type.to_bytes()

bumble/profiles/gmap.py

@@ -22,7 +22,6 @@ from typing import Optional
 
 from bumble.gatt import (
     TemplateService,
-    DelegatedCharacteristicAdapter,
     Characteristic,
     GATT_GAMING_AUDIO_SERVICE,
     GATT_GMAP_ROLE_CHARACTERISTIC,
@@ -31,7 +30,8 @@ from bumble.gatt import (
     GATT_BGS_FEATURES_CHARACTERISTIC,
     GATT_BGR_FEATURES_CHARACTERISTIC,
 )
-from bumble.gatt_client import ProfileServiceProxy, ServiceProxy
+from bumble.gatt_adapters import DelegatedCharacteristicProxyAdapter
+from bumble.gatt_client import CharacteristicProxy, ProfileServiceProxy, ServiceProxy
 from enum import IntFlag
 
 
@@ -150,10 +150,15 @@ class GamingAudioService(TemplateService):
 class GamingAudioServiceProxy(ProfileServiceProxy):
     SERVICE_CLASS = GamingAudioService
 
+    ugg_features: Optional[CharacteristicProxy[UggFeatures]] = None
+    ugt_features: Optional[CharacteristicProxy[UgtFeatures]] = None
+    bgs_features: Optional[CharacteristicProxy[BgsFeatures]] = None
+    bgr_features: Optional[CharacteristicProxy[BgrFeatures]] = None
+
     def __init__(self, service_proxy: ServiceProxy) -> None:
         self.service_proxy = service_proxy
 
-        self.gmap_role = DelegatedCharacteristicAdapter(
+        self.gmap_role = DelegatedCharacteristicProxyAdapter(
             service_proxy.get_required_characteristic_by_uuid(
                 GATT_GMAP_ROLE_CHARACTERISTIC
             ),
@@ -163,31 +168,31 @@ class GamingAudioServiceProxy(ProfileServiceProxy):
         if characteristics := service_proxy.get_characteristics_by_uuid(
             GATT_UGG_FEATURES_CHARACTERISTIC
         ):
-            self.ugg_features = DelegatedCharacteristicAdapter(
+            self.ugg_features = DelegatedCharacteristicProxyAdapter(
-                characteristic=characteristics[0],
+                characteristics[0],
                 decode=lambda value: UggFeatures(value[0]),
             )
 
         if characteristics := service_proxy.get_characteristics_by_uuid(
             GATT_UGT_FEATURES_CHARACTERISTIC
         ):
-            self.ugt_features = DelegatedCharacteristicAdapter(
+            self.ugt_features = DelegatedCharacteristicProxyAdapter(
-                characteristic=characteristics[0],
+                characteristics[0],
                 decode=lambda value: UgtFeatures(value[0]),
             )
 
         if characteristics := service_proxy.get_characteristics_by_uuid(
             GATT_BGS_FEATURES_CHARACTERISTIC
         ):
-            self.bgs_features = DelegatedCharacteristicAdapter(
+            self.bgs_features = DelegatedCharacteristicProxyAdapter(
-                characteristic=characteristics[0],
+                characteristics[0],
                 decode=lambda value: BgsFeatures(value[0]),
             )
 
         if characteristics := service_proxy.get_characteristics_by_uuid(
             GATT_BGR_FEATURES_CHARACTERISTIC
         ):
-            self.bgr_features = DelegatedCharacteristicAdapter(
+            self.bgr_features = DelegatedCharacteristicProxyAdapter(
-                characteristic=characteristics[0],
+                characteristics[0],
                 decode=lambda value: BgrFeatures(value[0]),
             )

bumble/profiles/hap.py

@@ -18,14 +18,15 @@
 from __future__ import annotations
 import asyncio
 import functools
-from bumble import att, gatt, gatt_client
+from dataclasses import dataclass, field
+import logging
+from typing import Any, Dict, List, Optional, Set, Union
+
+from bumble import att, gatt, gatt_adapters, gatt_client
 from bumble.core import InvalidArgumentError, InvalidStateError
 from bumble.device import Device, Connection
 from bumble.utils import AsyncRunner, OpenIntEnum
 from bumble.hci import Address
-from dataclasses import dataclass, field
-import logging
-from typing import Any, Dict, List, Optional, Set, Union
 
 
 # -----------------------------------------------------------------------------
@@ -631,11 +632,12 @@ class HearingAccessServiceProxy(gatt_client.ProfileServiceProxy):
 
     hearing_aid_preset_control_point: gatt_client.CharacteristicProxy
     preset_control_point_indications: asyncio.Queue
+    active_preset_index_notification: asyncio.Queue
 
     def __init__(self, service_proxy: gatt_client.ServiceProxy) -> None:
         self.service_proxy = service_proxy
 
-        self.server_features = gatt.PackedCharacteristicAdapter(
+        self.server_features = gatt_adapters.PackedCharacteristicProxyAdapter(
             service_proxy.get_characteristics_by_uuid(
                 gatt.GATT_HEARING_AID_FEATURES_CHARACTERISTIC
             )[0],
@@ -648,7 +650,7 @@ class HearingAccessServiceProxy(gatt_client.ProfileServiceProxy):
             )[0]
         )
 
-        self.active_preset_index = gatt.PackedCharacteristicAdapter(
+        self.active_preset_index = gatt_adapters.PackedCharacteristicProxyAdapter(
             service_proxy.get_characteristics_by_uuid(
                 gatt.GATT_ACTIVE_PRESET_INDEX_CHARACTERISTIC
             )[0],

bumble/profiles/heart_rate_service.py

@@ -16,13 +16,14 @@
 # -----------------------------------------------------------------------------
 # Imports
 # -----------------------------------------------------------------------------
+from __future__ import annotations
 from enum import IntEnum
 import struct
+from typing import Optional
 
 from bumble import core
-from ..gatt_client import ProfileServiceProxy
+from bumble.att import ATT_Error
-from ..att import ATT_Error
+from bumble.gatt import (
-from ..gatt import (
     GATT_HEART_RATE_SERVICE,
     GATT_HEART_RATE_MEASUREMENT_CHARACTERISTIC,
     GATT_BODY_SENSOR_LOCATION_CHARACTERISTIC,
@@ -30,10 +31,13 @@ from ..gatt import (
     TemplateService,
     Characteristic,
     CharacteristicValue,
-    SerializableCharacteristicAdapter,
+)
+from bumble.gatt_adapters import (
     DelegatedCharacteristicAdapter,
     PackedCharacteristicAdapter,
+    SerializableCharacteristicAdapter,
 )
+from bumble.gatt_client import CharacteristicProxy, ProfileServiceProxy
 
 
 # -----------------------------------------------------------------------------
@@ -43,6 +47,10 @@ class HeartRateService(TemplateService):
     CONTROL_POINT_NOT_SUPPORTED = 0x80
     RESET_ENERGY_EXPENDED = 0x01
 
+    heart_rate_measurement_characteristic: Characteristic[HeartRateMeasurement]
+    body_sensor_location_characteristic: Characteristic[BodySensorLocation]
+    heart_rate_control_point_characteristic: Characteristic[int]
+
     class BodySensorLocation(IntEnum):
         OTHER = 0
         CHEST = 1
@@ -198,6 +206,14 @@ class HeartRateService(TemplateService):
 class HeartRateServiceProxy(ProfileServiceProxy):
     SERVICE_CLASS = HeartRateService
 
+    heart_rate_measurement: Optional[
+        CharacteristicProxy[HeartRateService.HeartRateMeasurement]
+    ]
+    body_sensor_location: Optional[
+        CharacteristicProxy[HeartRateService.BodySensorLocation]
+    ]
+    heart_rate_control_point: Optional[CharacteristicProxy[int]]
+
     def __init__(self, service_proxy):
         self.service_proxy = service_proxy
 

bumble/profiles/mcp.py

@@ -208,7 +208,7 @@ class MediaControlService(gatt.TemplateService):
             properties=gatt.Characteristic.Properties.READ
             | gatt.Characteristic.Properties.NOTIFY,
             permissions=gatt.Characteristic.Permissions.READ_REQUIRES_ENCRYPTION,
-            value=media_player_name or 'Bumble Player',
+            value=(media_player_name or 'Bumble Player').encode(),
         )
         self.track_changed_characteristic = gatt.Characteristic(
             uuid=gatt.GATT_TRACK_CHANGED_CHARACTERISTIC,
@@ -247,14 +247,16 @@ class MediaControlService(gatt.TemplateService):
             permissions=gatt.Characteristic.Permissions.READ_REQUIRES_ENCRYPTION,
             value=b'',
         )
-        self.media_control_point_characteristic = gatt.Characteristic(
+        self.media_control_point_characteristic: gatt.Characteristic[bytes] = (
-            uuid=gatt.GATT_MEDIA_CONTROL_POINT_CHARACTERISTIC,
+            gatt.Characteristic(
-            properties=gatt.Characteristic.Properties.WRITE
+                uuid=gatt.GATT_MEDIA_CONTROL_POINT_CHARACTERISTIC,
-            | gatt.Characteristic.Properties.WRITE_WITHOUT_RESPONSE
+                properties=gatt.Characteristic.Properties.WRITE
-            | gatt.Characteristic.Properties.NOTIFY,
+                | gatt.Characteristic.Properties.WRITE_WITHOUT_RESPONSE
-            permissions=gatt.Characteristic.Permissions.READ_REQUIRES_ENCRYPTION
+                | gatt.Characteristic.Properties.NOTIFY,
-            | gatt.Characteristic.Permissions.WRITE_REQUIRES_ENCRYPTION,
+                permissions=gatt.Characteristic.Permissions.READ_REQUIRES_ENCRYPTION
-            value=gatt.CharacteristicValue(write=self.on_media_control_point),
+                | gatt.Characteristic.Permissions.WRITE_REQUIRES_ENCRYPTION,
+                value=gatt.CharacteristicValue(write=self.on_media_control_point),
+            )
         )
         self.media_control_point_opcodes_supported_characteristic = gatt.Characteristic(
             uuid=gatt.GATT_MEDIA_CONTROL_POINT_OPCODES_SUPPORTED_CHARACTERISTIC,

bumble/profiles/pacs.py

@@ -25,6 +25,7 @@ from typing import Optional, Sequence, Union
 from bumble.profiles.bap import AudioLocation, CodecSpecificCapabilities, ContextType
 from bumble.profiles import le_audio
 from bumble import gatt
+from bumble import gatt_adapters
 from bumble import gatt_client
 from bumble import hci
 
@@ -185,34 +186,42 @@ class PublishedAudioCapabilitiesService(gatt.TemplateService):
 class PublishedAudioCapabilitiesServiceProxy(gatt_client.ProfileServiceProxy):
     SERVICE_CLASS = PublishedAudioCapabilitiesService
 
-    sink_pac: Optional[gatt.DelegatedCharacteristicAdapter] = None
+    sink_pac: Optional[gatt_client.CharacteristicProxy[list[PacRecord]]] = None
-    sink_audio_locations: Optional[gatt.DelegatedCharacteristicAdapter] = None
+    sink_audio_locations: Optional[gatt_client.CharacteristicProxy[AudioLocation]] = (
-    source_pac: Optional[gatt.DelegatedCharacteristicAdapter] = None
+        None
-    source_audio_locations: Optional[gatt.DelegatedCharacteristicAdapter] = None
+    )
-    available_audio_contexts: gatt.DelegatedCharacteristicAdapter
+    source_pac: Optional[gatt_client.CharacteristicProxy[list[PacRecord]]] = None
-    supported_audio_contexts: gatt.DelegatedCharacteristicAdapter
+    source_audio_locations: Optional[gatt_client.CharacteristicProxy[AudioLocation]] = (
+        None
+    )
+    available_audio_contexts: gatt_client.CharacteristicProxy[tuple[ContextType, ...]]
+    supported_audio_contexts: gatt_client.CharacteristicProxy[tuple[ContextType, ...]]
 
     def __init__(self, service_proxy: gatt_client.ServiceProxy):
         self.service_proxy = service_proxy
 
-        self.available_audio_contexts = gatt.DelegatedCharacteristicAdapter(
+        self.available_audio_contexts = (
-            service_proxy.get_required_characteristic_by_uuid(
+            gatt_adapters.DelegatedCharacteristicProxyAdapter(
-                gatt.GATT_AVAILABLE_AUDIO_CONTEXTS_CHARACTERISTIC
+                service_proxy.get_required_characteristic_by_uuid(
-            ),
+                    gatt.GATT_AVAILABLE_AUDIO_CONTEXTS_CHARACTERISTIC
-            decode=lambda x: tuple(map(ContextType, struct.unpack('<HH', x))),
+                ),
+                decode=lambda x: tuple(map(ContextType, struct.unpack('<HH', x))),
+            )
         )
 
-        self.supported_audio_contexts = gatt.DelegatedCharacteristicAdapter(
+        self.supported_audio_contexts = (
-            service_proxy.get_required_characteristic_by_uuid(
+            gatt_adapters.DelegatedCharacteristicProxyAdapter(
-                gatt.GATT_SUPPORTED_AUDIO_CONTEXTS_CHARACTERISTIC
+                service_proxy.get_required_characteristic_by_uuid(
-            ),
+                    gatt.GATT_SUPPORTED_AUDIO_CONTEXTS_CHARACTERISTIC
-            decode=lambda x: tuple(map(ContextType, struct.unpack('<HH', x))),
+                ),
+                decode=lambda x: tuple(map(ContextType, struct.unpack('<HH', x))),
+            )
         )
 
         if characteristics := service_proxy.get_characteristics_by_uuid(
             gatt.GATT_SINK_PAC_CHARACTERISTIC
         ):
-            self.sink_pac = gatt.DelegatedCharacteristicAdapter(
+            self.sink_pac = gatt_adapters.DelegatedCharacteristicProxyAdapter(
                 characteristics[0],
                 decode=PacRecord.list_from_bytes,
             )
@@ -220,7 +229,7 @@ class PublishedAudioCapabilitiesServiceProxy(gatt_client.ProfileServiceProxy):
         if characteristics := service_proxy.get_characteristics_by_uuid(
             gatt.GATT_SOURCE_PAC_CHARACTERISTIC
         ):
-            self.source_pac = gatt.DelegatedCharacteristicAdapter(
+            self.source_pac = gatt_adapters.DelegatedCharacteristicProxyAdapter(
                 characteristics[0],
                 decode=PacRecord.list_from_bytes,
             )
@@ -228,15 +237,19 @@ class PublishedAudioCapabilitiesServiceProxy(gatt_client.ProfileServiceProxy):
         if characteristics := service_proxy.get_characteristics_by_uuid(
             gatt.GATT_SINK_AUDIO_LOCATION_CHARACTERISTIC
         ):
-            self.sink_audio_locations = gatt.DelegatedCharacteristicAdapter(
+            self.sink_audio_locations = (
-                characteristics[0],
+                gatt_adapters.DelegatedCharacteristicProxyAdapter(
-                decode=lambda x: AudioLocation(struct.unpack('<I', x)[0]),
+                    characteristics[0],
+                    decode=lambda x: AudioLocation(struct.unpack('<I', x)[0]),
+                )
             )
 
         if characteristics := service_proxy.get_characteristics_by_uuid(
             gatt.GATT_SOURCE_AUDIO_LOCATION_CHARACTERISTIC
         ):
-            self.source_audio_locations = gatt.DelegatedCharacteristicAdapter(
+            self.source_audio_locations = (
-                characteristics[0],
+                gatt_adapters.DelegatedCharacteristicProxyAdapter(
-                decode=lambda x: AudioLocation(struct.unpack('<I', x)[0]),
+                    characteristics[0],
+                    decode=lambda x: AudioLocation(struct.unpack('<I', x)[0]),
+                )
             )

bumble/profiles/tmap.py

@@ -24,11 +24,11 @@ import struct
 from bumble.gatt import (
     TemplateService,
     Characteristic,
-    DelegatedCharacteristicAdapter,
     GATT_TELEPHONY_AND_MEDIA_AUDIO_SERVICE,
     GATT_TMAP_ROLE_CHARACTERISTIC,
 )
-from bumble.gatt_client import ProfileServiceProxy, ServiceProxy
+from bumble.gatt_adapters import DelegatedCharacteristicProxyAdapter
+from bumble.gatt_client import CharacteristicProxy, ProfileServiceProxy, ServiceProxy
 
 
 # -----------------------------------------------------------------------------
@@ -53,6 +53,8 @@ class Role(enum.IntFlag):
 class TelephonyAndMediaAudioService(TemplateService):
     UUID = GATT_TELEPHONY_AND_MEDIA_AUDIO_SERVICE
 
+    role_characteristic: Characteristic[bytes]
+
     def __init__(self, role: Role):
         self.role_characteristic = Characteristic(
             GATT_TMAP_ROLE_CHARACTERISTIC,
@@ -68,12 +70,12 @@ class TelephonyAndMediaAudioService(TemplateService):
 class TelephonyAndMediaAudioServiceProxy(ProfileServiceProxy):
     SERVICE_CLASS = TelephonyAndMediaAudioService
 
-    role: DelegatedCharacteristicAdapter
+    role: CharacteristicProxy[Role]
 
     def __init__(self, service_proxy: ServiceProxy):
         self.service_proxy = service_proxy
 
-        self.role = DelegatedCharacteristicAdapter(
+        self.role = DelegatedCharacteristicProxyAdapter(
             service_proxy.get_required_characteristic_by_uuid(
                 GATT_TMAP_ROLE_CHARACTERISTIC
             ),

bumble/profiles/vcs.py

@@ -25,6 +25,7 @@ from typing import Optional, Sequence
 from bumble import att
 from bumble import device
 from bumble import gatt
+from bumble import gatt_adapters
 from bumble import gatt_client
 
 
@@ -209,14 +210,14 @@ class VolumeControlService(gatt.TemplateService):
 class VolumeControlServiceProxy(gatt_client.ProfileServiceProxy):
     SERVICE_CLASS = VolumeControlService
 
-    volume_control_point: gatt_client.CharacteristicProxy
+    volume_control_point: gatt_client.CharacteristicProxy[bytes]
-    volume_state: gatt.SerializableCharacteristicAdapter
+    volume_state: gatt_client.CharacteristicProxy[VolumeState]
-    volume_flags: gatt.DelegatedCharacteristicAdapter
+    volume_flags: gatt_client.CharacteristicProxy[VolumeFlags]
 
     def __init__(self, service_proxy: gatt_client.ServiceProxy) -> None:
         self.service_proxy = service_proxy
 
-        self.volume_state = gatt.SerializableCharacteristicAdapter(
+        self.volume_state = gatt_adapters.SerializableCharacteristicProxyAdapter(
             service_proxy.get_required_characteristic_by_uuid(
                 gatt.GATT_VOLUME_STATE_CHARACTERISTIC
             ),
@@ -227,7 +228,7 @@ class VolumeControlServiceProxy(gatt_client.ProfileServiceProxy):
             gatt.GATT_VOLUME_CONTROL_POINT_CHARACTERISTIC
         )
 
-        self.volume_flags = gatt.DelegatedCharacteristicAdapter(
+        self.volume_flags = gatt_adapters.DelegatedCharacteristicProxyAdapter(
             service_proxy.get_required_characteristic_by_uuid(
                 gatt.GATT_VOLUME_FLAGS_CHARACTERISTIC
             ),

bumble/profiles/vocs.py

@@ -24,17 +24,19 @@ from bumble.device import Connection
 from bumble.att import ATT_Error
 from bumble.gatt import (
     Characteristic,
-    DelegatedCharacteristicAdapter,
     TemplateService,
     CharacteristicValue,
-    SerializableCharacteristicAdapter,
-    UTF8CharacteristicAdapter,
     GATT_VOLUME_OFFSET_CONTROL_SERVICE,
     GATT_VOLUME_OFFSET_STATE_CHARACTERISTIC,
     GATT_AUDIO_LOCATION_CHARACTERISTIC,
     GATT_VOLUME_OFFSET_CONTROL_POINT_CHARACTERISTIC,
     GATT_AUDIO_OUTPUT_DESCRIPTION_CHARACTERISTIC,
 )
+from bumble.gatt_adapters import (
+    DelegatedCharacteristicProxyAdapter,
+    SerializableCharacteristicProxyAdapter,
+    UTF8CharacteristicProxyAdapter,
+)
 from bumble.gatt_client import ProfileServiceProxy, ServiceProxy
 from bumble.utils import OpenIntEnum
 from bumble.profiles.bap import AudioLocation
@@ -67,7 +69,7 @@ class ErrorCode(OpenIntEnum):
 class VolumeOffsetState:
     volume_offset: int = 0
     change_counter: int = 0
-    attribute_value: Optional[CharacteristicValue] = None
+    attribute: Optional[Characteristic] = None
 
     def __bytes__(self) -> bytes:
         return struct.pack('<hB', self.volume_offset, self.change_counter)
@@ -81,8 +83,8 @@ class VolumeOffsetState:
         self.change_counter = (self.change_counter + 1) % (CHANGE_COUNTER_MAX_VALUE + 1)
 
     async def notify_subscribers_via_connection(self, connection: Connection) -> None:
-        assert self.attribute_value is not None
+        assert self.attribute is not None
-        await connection.device.notify_subscribers(attribute=self.attribute_value)
+        await connection.device.notify_subscribers(attribute=self.attribute)
 
     def on_read(self, _connection: Optional[Connection]) -> bytes:
         return bytes(self)
@@ -91,7 +93,7 @@ class VolumeOffsetState:
 @dataclass
 class VocsAudioLocation:
     audio_location: AudioLocation = AudioLocation.NOT_ALLOWED
-    attribute_value: Optional[CharacteristicValue] = None
+    attribute: Optional[Characteristic] = None
 
     def __bytes__(self) -> bytes:
         return struct.pack('<I', self.audio_location)
@@ -106,10 +108,10 @@ class VocsAudioLocation:
 
     async def on_write(self, connection: Optional[Connection], value: bytes) -> None:
         assert connection
-        assert self.attribute_value
+        assert self.attribute
 
         self.audio_location = AudioLocation(int.from_bytes(value, 'little'))
-        await connection.device.notify_subscribers(attribute=self.attribute_value)
+        await connection.device.notify_subscribers(attribute=self.attribute)
 
 
 @dataclass
@@ -148,7 +150,7 @@ class VolumeOffsetControlPoint:
 @dataclass
 class AudioOutputDescription:
     audio_output_description: str = ''
-    attribute_value: Optional[CharacteristicValue] = None
+    attribute: Optional[Characteristic] = None
 
     @classmethod
     def from_bytes(cls, data: bytes):
@@ -162,10 +164,10 @@ class AudioOutputDescription:
 
     async def on_write(self, connection: Optional[Connection], value: bytes) -> None:
         assert connection
-        assert self.attribute_value
+        assert self.attribute
 
         self.audio_output_description = value.decode('utf-8')
-        await connection.device.notify_subscribers(attribute=self.attribute_value)
+        await connection.device.notify_subscribers(attribute=self.attribute)
 
 
 # -----------------------------------------------------------------------------
@@ -197,7 +199,7 @@ class VolumeOffsetControlService(TemplateService):
             VolumeOffsetControlPoint(self.volume_offset_state)
         )
 
-        self.volume_offset_state_characteristic = Characteristic(
+        self.volume_offset_state_characteristic: Characteristic[bytes] = Characteristic(
             uuid=GATT_VOLUME_OFFSET_STATE_CHARACTERISTIC,
             properties=(
                 Characteristic.Properties.READ | Characteristic.Properties.NOTIFY
@@ -206,7 +208,7 @@ class VolumeOffsetControlService(TemplateService):
             value=CharacteristicValue(read=self.volume_offset_state.on_read),
         )
 
-        self.audio_location_characteristic = Characteristic(
+        self.audio_location_characteristic: Characteristic[bytes] = Characteristic(
             uuid=GATT_AUDIO_LOCATION_CHARACTERISTIC,
             properties=(
                 Characteristic.Properties.READ
@@ -222,33 +224,39 @@ class VolumeOffsetControlService(TemplateService):
                 write=self.audio_location.on_write,
             ),
         )
-        self.audio_location.attribute_value = self.audio_location_characteristic.value
+        self.audio_location.attribute = self.audio_location_characteristic
 
-        self.volume_offset_control_point_characteristic = Characteristic(
+        self.volume_offset_control_point_characteristic: Characteristic[bytes] = (
-            uuid=GATT_VOLUME_OFFSET_CONTROL_POINT_CHARACTERISTIC,
+            Characteristic(
-            properties=Characteristic.Properties.WRITE,
+                uuid=GATT_VOLUME_OFFSET_CONTROL_POINT_CHARACTERISTIC,
-            permissions=Characteristic.Permissions.WRITE_REQUIRES_ENCRYPTION,
+                properties=Characteristic.Properties.WRITE,
-            value=CharacteristicValue(write=self.volume_offset_control_point.on_write),
+                permissions=Characteristic.Permissions.WRITE_REQUIRES_ENCRYPTION,
+                value=CharacteristicValue(
+                    write=self.volume_offset_control_point.on_write
+                ),
+            )
         )
 
-        self.audio_output_description_characteristic = Characteristic(
+        self.audio_output_description_characteristic: Characteristic[bytes] = (
-            uuid=GATT_AUDIO_OUTPUT_DESCRIPTION_CHARACTERISTIC,
+            Characteristic(
-            properties=(
+                uuid=GATT_AUDIO_OUTPUT_DESCRIPTION_CHARACTERISTIC,
-                Characteristic.Properties.READ
+                properties=(
-                | Characteristic.Properties.NOTIFY
+                    Characteristic.Properties.READ
-                | Characteristic.Properties.WRITE_WITHOUT_RESPONSE
+                    | Characteristic.Properties.NOTIFY
-            ),
+                    | Characteristic.Properties.WRITE_WITHOUT_RESPONSE
-            permissions=(
+                ),
-                Characteristic.Permissions.READ_REQUIRES_ENCRYPTION
+                permissions=(
-                | Characteristic.Permissions.WRITE_REQUIRES_ENCRYPTION
+                    Characteristic.Permissions.READ_REQUIRES_ENCRYPTION
-            ),
+                    | Characteristic.Permissions.WRITE_REQUIRES_ENCRYPTION
-            value=CharacteristicValue(
+                ),
-                read=self.audio_output_description.on_read,
+                value=CharacteristicValue(
-                write=self.audio_output_description.on_write,
+                    read=self.audio_output_description.on_read,
-            ),
+                    write=self.audio_output_description.on_write,
+                ),
+            )
         )
-        self.audio_output_description.attribute_value = (
+        self.audio_output_description.attribute = (
-            self.audio_output_description_characteristic.value
+            self.audio_output_description_characteristic
         )
 
         super().__init__(
@@ -271,14 +279,14 @@ class VolumeOffsetControlServiceProxy(ProfileServiceProxy):
     def __init__(self, service_proxy: ServiceProxy) -> None:
         self.service_proxy = service_proxy
 
-        self.volume_offset_state = SerializableCharacteristicAdapter(
+        self.volume_offset_state = SerializableCharacteristicProxyAdapter(
             service_proxy.get_required_characteristic_by_uuid(
                 GATT_VOLUME_OFFSET_STATE_CHARACTERISTIC
             ),
             VolumeOffsetState,
         )
 
-        self.audio_location = DelegatedCharacteristicAdapter(
+        self.audio_location = DelegatedCharacteristicProxyAdapter(
             service_proxy.get_required_characteristic_by_uuid(
                 GATT_AUDIO_LOCATION_CHARACTERISTIC
             ),
@@ -292,7 +300,7 @@ class VolumeOffsetControlServiceProxy(ProfileServiceProxy):
             )
         )
 
-        self.audio_output_description = UTF8CharacteristicAdapter(
+        self.audio_output_description = UTF8CharacteristicProxyAdapter(
             service_proxy.get_required_characteristic_by_uuid(
                 GATT_AUDIO_OUTPUT_DESCRIPTION_CHARACTERISTIC
             )

bumble/utils.py

@@ -502,3 +502,13 @@ class ByteSerializable(Protocol):
     def from_bytes(cls, data: bytes) -> Self: ...
 
     def __bytes__(self) -> bytes: ...
+
+
+# -----------------------------------------------------------------------------
+class IntConvertible(Protocol):
+    """
+    Type protocol for classes that can be instantiated from int and converted to int.
+    """
+
+    def __init__(self, value: int) -> None: ...
+    def __int__(self) -> int: ...

examples/heart_rate_server.py

@@ -102,7 +102,6 @@ async def main() -> None:
         )
 
         # Notify subscribers of the current value as soon as they subscribe
-        @heart_rate_service.heart_rate_measurement_characteristic.on('subscription')
         def on_subscription(connection, notify_enabled, indicate_enabled):
             if notify_enabled or indicate_enabled:
                 AsyncRunner.spawn(
@@ -112,6 +111,10 @@ async def main() -> None:
                     )
                 )
 
+        heart_rate_service.heart_rate_measurement_characteristic.on(
+            'subscription', on_subscription
+        )
+
         # Go!
         await device.power_on()
         await device.start_advertising(auto_restart=True)

examples/run_gatt_client_and_server.py

@@ -70,13 +70,13 @@ async def main() -> None:
     descriptor = Descriptor(
         GATT_CHARACTERISTIC_USER_DESCRIPTION_DESCRIPTOR,
         Descriptor.READABLE,
-        'My Description',
+        'My Description'.encode(),
     )
-    manufacturer_name_characteristic = Characteristic(
+    manufacturer_name_characteristic = Characteristic[bytes](
         GATT_MANUFACTURER_NAME_STRING_CHARACTERISTIC,
         Characteristic.Properties.READ,
         Characteristic.READABLE,
-        "Fitbit",
+        "Fitbit".encode(),
         [descriptor],
     )
     device_info_service = Service(

examples/run_gatt_server.py

@@ -94,13 +94,13 @@ async def main() -> None:
         descriptor = Descriptor(
             GATT_CHARACTERISTIC_USER_DESCRIPTION_DESCRIPTOR,
             Descriptor.READABLE,
-            'My Description',
+            'My Description'.encode(),
         )
         manufacturer_name_characteristic = Characteristic(
             GATT_MANUFACTURER_NAME_STRING_CHARACTERISTIC,
             Characteristic.Properties.READ,
             Characteristic.READABLE,
-            'Fitbit',
+            'Fitbit'.encode(),
             [descriptor],
         )
         device_info_service = Service(

examples/run_gatt_with_adapters.py

@@ -1,4 +1,4 @@
-# Copyright 2024 Google LLC
+# Copyright 2025 Google LLC
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
 # you may not use this file except in compliance with the License.
@@ -18,6 +18,8 @@
 from __future__ import annotations
 import asyncio
 import dataclasses
+import functools
+import enum
 import logging
 import os
 import random
@@ -28,6 +30,8 @@ from typing import Any, List, Union
 from bumble.device import Device, Peer
 from bumble import transport
 from bumble import gatt
+from bumble import gatt_adapters
+from bumble import gatt_client
 from bumble import hci
 from bumble import core
 
@@ -36,6 +40,9 @@ from bumble import core
 SERVICE_UUID = core.UUID("50DB505C-8AC4-4738-8448-3B1D9CC09CC5")
 CHARACTERISTIC_UUID_BASE = "D901B45B-4916-412E-ACCA-0000000000"
 
+DEFAULT_CLIENT_ADDRESS = "F0:F1:F2:F3:F4:F5"
+DEFAULT_SERVER_ADDRESS = "F1:F2:F3:F4:F5:F6"
+
 
 # -----------------------------------------------------------------------------
 @dataclasses.dataclass
@@ -65,6 +72,12 @@ class CustomClass:
         return struct.pack(">II", self.a, self.b)
 
 
+# -----------------------------------------------------------------------------
+class CustomEnum(enum.IntEnum):
+    FOO = 1234
+    BAR = 5678
+
+
 # -----------------------------------------------------------------------------
 async def client(device: Device, address: hci.Address) -> None:
     print(f'=== Connecting to {address}...')
@@ -78,8 +91,8 @@ async def client(device: Device, address: hci.Address) -> None:
     print("*** Discovery complete")
 
     service = peer.get_services_by_uuid(SERVICE_UUID)[0]
-    characteristics = []
+    characteristics: list[gatt_client.CharacteristicProxy] = []
-    for index in range(1, 9):
+    for index in range(1, 10):
         characteristics.append(
             service.get_characteristics_by_uuid(
                 core.UUID(CHARACTERISTIC_UUID_BASE + f"{index:02X}")
@@ -91,59 +104,92 @@ async def client(device: Device, address: hci.Address) -> None:
         value = await characteristic.read_value()
         print(f"### {characteristic} = {value!r} ({value.hex()})")
 
+    # Subscribe to all characteristics as a raw bytes listener.
+    def on_raw_characteristic_update(characteristic, value):
+        print(f"^^^ Update[RAW] {characteristic.uuid} value = {value.hex()}")
+
+    for characteristic in characteristics:
+        await characteristic.subscribe(
+            functools.partial(on_raw_characteristic_update, characteristic)
+        )
+
+    # Function to subscribe to adapted characteristics
+    def on_adapted_characteristic_update(characteristic, value):
+        print(
+            f"^^^ Update[ADAPTED] {characteristic.uuid} value = {value!r}, "
+            f"type={type(value)}"
+        )
+
     # Static characteristic with a bytes value.
     c1 = characteristics[0]
     c1_value = await c1.read_value()
     print(f"@@@ C1 {c1} value = {c1_value!r} (type={type(c1_value)})")
     await c1.write_value("happy π day".encode("utf-8"))
+    await c1.subscribe(functools.partial(on_adapted_characteristic_update, c1))
 
     # Static characteristic with a string value.
-    c2 = gatt.UTF8CharacteristicAdapter(characteristics[1])
+    c2 = gatt_adapters.UTF8CharacteristicProxyAdapter(characteristics[1])
     c2_value = await c2.read_value()
     print(f"@@@ C2 {c2} value = {c2_value} (type={type(c2_value)})")
     await c2.write_value("happy π day")
+    await c2.subscribe(functools.partial(on_adapted_characteristic_update, c2))
 
     # Static characteristic with a tuple value.
-    c3 = gatt.PackedCharacteristicAdapter(characteristics[2], ">III")
+    c3 = gatt_adapters.PackedCharacteristicProxyAdapter(characteristics[2], ">III")
     c3_value = await c3.read_value()
     print(f"@@@ C3 {c3} value = {c3_value} (type={type(c3_value)})")
     await c3.write_value((2001, 2002, 2003))
+    await c3.subscribe(functools.partial(on_adapted_characteristic_update, c3))
 
     # Static characteristic with a named tuple value.
-    c4 = gatt.MappedCharacteristicAdapter(
+    c4 = gatt_adapters.MappedCharacteristicProxyAdapter(
         characteristics[3], ">III", ["f1", "f2", "f3"]
     )
     c4_value = await c4.read_value()
     print(f"@@@ C4 {c4} value = {c4_value} (type={type(c4_value)})")
     await c4.write_value({"f1": 4001, "f2": 4002, "f3": 4003})
+    await c4.subscribe(functools.partial(on_adapted_characteristic_update, c4))
 
     # Static characteristic with a serializable value.
-    c5 = gatt.SerializableCharacteristicAdapter(
+    c5 = gatt_adapters.SerializableCharacteristicProxyAdapter(
         characteristics[4], CustomSerializableClass
     )
     c5_value = await c5.read_value()
     print(f"@@@ C5 {c5} value = {c5_value} (type={type(c5_value)})")
     await c5.write_value(CustomSerializableClass(56, 57))
+    await c5.subscribe(functools.partial(on_adapted_characteristic_update, c5))
 
     # Static characteristic with a delegated value.
-    c6 = gatt.DelegatedCharacteristicAdapter(
+    c6 = gatt_adapters.DelegatedCharacteristicProxyAdapter(
         characteristics[5], encode=CustomClass.encode, decode=CustomClass.decode
     )
     c6_value = await c6.read_value()
     print(f"@@@ C6 {c6} value = {c6_value} (type={type(c6_value)})")
     await c6.write_value(CustomClass(6, 7))
+    await c6.subscribe(functools.partial(on_adapted_characteristic_update, c6))
 
     # Dynamic characteristic with a bytes value.
     c7 = characteristics[6]
     c7_value = await c7.read_value()
     print(f"@@@ C7 {c7} value = {c7_value!r} (type={type(c7_value)})")
     await c7.write_value(bytes.fromhex("01020304"))
+    await c7.subscribe(functools.partial(on_adapted_characteristic_update, c7))
 
     # Dynamic characteristic with a string value.
-    c8 = gatt.UTF8CharacteristicAdapter(characteristics[7])
+    c8 = gatt_adapters.UTF8CharacteristicProxyAdapter(characteristics[7])
     c8_value = await c8.read_value()
     print(f"@@@ C8 {c8} value = {c8_value} (type={type(c8_value)})")
     await c8.write_value("howdy")
+    await c8.subscribe(functools.partial(on_adapted_characteristic_update, c8))
+
+    # Static characteristic with an enum value
+    c9 = gatt_adapters.EnumCharacteristicProxyAdapter(
+        characteristics[8], CustomEnum, 3, 'big'
+    )
+    c9_value = await c9.read_value()
+    print(f"@@@ C9 {c9} value = {c9_value.name} (type={type(c9_value)})")
+    await c9.write_value(CustomEnum.BAR)
+    await c9.subscribe(functools.partial(on_adapted_characteristic_update, c9))
 
 
 # -----------------------------------------------------------------------------
@@ -175,142 +221,213 @@ def on_characteristic_write(characteristic: gatt.Characteristic, value: Any) ->
     print(f"<<< WRITE: {characteristic} <- {value}  ({type(value)})")
 
 
+# -----------------------------------------------------------------------------
+async def server(device: Device) -> None:
+    # Static characteristic with a bytes value.
+    c1 = gatt.Characteristic(
+        CHARACTERISTIC_UUID_BASE + "01",
+        gatt.Characteristic.Properties.READ
+        | gatt.Characteristic.Properties.WRITE
+        | gatt.Characteristic.Properties.NOTIFY,
+        gatt.Characteristic.READABLE | gatt.Characteristic.WRITEABLE,
+        b'hello',
+    )
+
+    # Static characteristic with a string value.
+    c2 = gatt_adapters.UTF8CharacteristicAdapter(
+        gatt.Characteristic(
+            CHARACTERISTIC_UUID_BASE + "02",
+            gatt.Characteristic.Properties.READ
+            | gatt.Characteristic.Properties.WRITE
+            | gatt.Characteristic.Properties.NOTIFY,
+            gatt.Characteristic.READABLE | gatt.Characteristic.WRITEABLE,
+            'hello',
+        )
+    )
+
+    # Static characteristic with a tuple value.
+    c3 = gatt_adapters.PackedCharacteristicAdapter(
+        gatt.Characteristic(
+            CHARACTERISTIC_UUID_BASE + "03",
+            gatt.Characteristic.Properties.READ
+            | gatt.Characteristic.Properties.WRITE
+            | gatt.Characteristic.Properties.NOTIFY,
+            gatt.Characteristic.READABLE | gatt.Characteristic.WRITEABLE,
+            (1007, 1008, 1009),
+        ),
+        ">III",
+    )
+
+    # Static characteristic with a named tuple value.
+    c4 = gatt_adapters.MappedCharacteristicAdapter(
+        gatt.Characteristic(
+            CHARACTERISTIC_UUID_BASE + "04",
+            gatt.Characteristic.Properties.READ
+            | gatt.Characteristic.Properties.WRITE
+            | gatt.Characteristic.Properties.NOTIFY,
+            gatt.Characteristic.READABLE | gatt.Characteristic.WRITEABLE,
+            {"f1": 3007, "f2": 3008, "f3": 3009},
+        ),
+        ">III",
+        ["f1", "f2", "f3"],
+    )
+
+    # Static characteristic with a serializable value.
+    c5 = gatt_adapters.SerializableCharacteristicAdapter(
+        gatt.Characteristic(
+            CHARACTERISTIC_UUID_BASE + "05",
+            gatt.Characteristic.Properties.READ
+            | gatt.Characteristic.Properties.WRITE
+            | gatt.Characteristic.Properties.NOTIFY,
+            gatt.Characteristic.READABLE | gatt.Characteristic.WRITEABLE,
+            CustomSerializableClass(11, 12),
+        ),
+        CustomSerializableClass,
+    )
+
+    # Static characteristic with a delegated value.
+    c6 = gatt_adapters.DelegatedCharacteristicAdapter(
+        gatt.Characteristic(
+            CHARACTERISTIC_UUID_BASE + "06",
+            gatt.Characteristic.Properties.READ
+            | gatt.Characteristic.Properties.WRITE
+            | gatt.Characteristic.Properties.NOTIFY,
+            gatt.Characteristic.READABLE | gatt.Characteristic.WRITEABLE,
+            CustomClass(1, 2),
+        ),
+        encode=CustomClass.encode,
+        decode=CustomClass.decode,
+    )
+
+    # Dynamic characteristic with a bytes value.
+    c7 = gatt.Characteristic(
+        CHARACTERISTIC_UUID_BASE + "07",
+        gatt.Characteristic.Properties.READ
+        | gatt.Characteristic.Properties.WRITE
+        | gatt.Characteristic.Properties.NOTIFY,
+        gatt.Characteristic.READABLE | gatt.Characteristic.WRITEABLE,
+        gatt.CharacteristicValue(
+            read=lambda connection: dynamic_read("bytes"),
+            write=lambda connection, value: dynamic_write("bytes", value),
+        ),
+    )
+
+    # Dynamic characteristic with a string value.
+    c8 = gatt_adapters.UTF8CharacteristicAdapter(
+        gatt.Characteristic(
+            CHARACTERISTIC_UUID_BASE + "08",
+            gatt.Characteristic.Properties.READ
+            | gatt.Characteristic.Properties.WRITE
+            | gatt.Characteristic.Properties.NOTIFY,
+            gatt.Characteristic.READABLE | gatt.Characteristic.WRITEABLE,
+            gatt.CharacteristicValue(
+                read=lambda connection: dynamic_read("string"),
+                write=lambda connection, value: dynamic_write("string", value),
+            ),
+        )
+    )
+
+    # Static characteristic with an enum value
+    c9 = gatt_adapters.EnumCharacteristicAdapter(
+        gatt.Characteristic(
+            CHARACTERISTIC_UUID_BASE + "09",
+            gatt.Characteristic.Properties.READ
+            | gatt.Characteristic.Properties.WRITE
+            | gatt.Characteristic.Properties.NOTIFY,
+            gatt.Characteristic.READABLE | gatt.Characteristic.WRITEABLE,
+            CustomEnum.FOO,
+        ),
+        cls=CustomEnum,
+        length=3,
+        byteorder='big',
+    )
+
+    characteristics: List[gatt.Characteristic] = [
+        c1,
+        c2,
+        c3,
+        c4,
+        c5,
+        c6,
+        c7,
+        c8,
+        c9,
+    ]
+
+    # Listen for read and write events.
+    for characteristic in characteristics:
+        characteristic.on(
+            "read",
+            lambda _, value, c=characteristic: on_characteristic_read(c, value),
+        )
+        characteristic.on(
+            "write",
+            lambda _, value, c=characteristic: on_characteristic_write(c, value),
+        )
+
+    device.add_service(gatt.Service(SERVICE_UUID, characteristics))
+
+    # Notify every 3 seconds
+    i = 0
+    while True:
+        await asyncio.sleep(3)
+
+        # Notifying can be done with the characteristic's current value, or
+        # by explicitly passing a value to notify with. Both variants are used
+        # here: for c1..c4 we set the value and then notify, for c4..c9 we notify
+        # with an explicit value.
+        c1.value = f'hello c1 {i}'.encode()
+        await device.notify_subscribers(c1)
+        c2.value = f'hello c2 {i}'
+        await device.notify_subscribers(c2)
+        c3.value = (1000 + i, 2000 + i, 3000 + i)
+        await device.notify_subscribers(c3)
+        c4.value = {"f1": 4000 + i, "f2": 5000 + i, "f3": 6000 + i}
+        await device.notify_subscribers(c4)
+        await device.notify_subscribers(c5, CustomSerializableClass(1000 + i, 2000 + i))
+        await device.notify_subscribers(c6, CustomClass(3000 + i, 4000 + i))
+        await device.notify_subscribers(c7, bytes([1, 2, 3, i % 256]))
+        await device.notify_subscribers(c8, f'hello c8 {i}')
+        await device.notify_subscribers(
+            c9, CustomEnum.FOO if i % 2 == 0 else CustomEnum.BAR
+        )
+
+        i += 1
+
+
 # -----------------------------------------------------------------------------
 async def main() -> None:
     if len(sys.argv) < 2:
-        print("Usage: run_gatt_with_adapters.py <transport-spec> [<bluetooth-address>]")
+        print("Usage: run_gatt_with_adapters.py <transport-spec> client|server")
-        print("example: run_gatt_with_adapters.py usb:0 E1:CA:72:48:C4:E8")
+        print("example: run_gatt_with_adapters.py usb:0 F0:F1:F2:F3:F4:F5")
         return
 
     async with await transport.open_transport(sys.argv[1]) as hci_transport:
+        is_client = sys.argv[2] == "client"
+
         # Create a device to manage the host
         device = Device.with_hci(
             "Bumble",
-            hci.Address("F0:F1:F2:F3:F4:F5"),
+            hci.Address(
+                DEFAULT_CLIENT_ADDRESS if is_client else DEFAULT_SERVER_ADDRESS
+            ),
             hci_transport.source,
             hci_transport.sink,
         )
 
-        # Static characteristic with a bytes value.
-        c1 = gatt.Characteristic(
-            CHARACTERISTIC_UUID_BASE + "01",
-            gatt.Characteristic.Properties.READ | gatt.Characteristic.Properties.WRITE,
-            gatt.Characteristic.READABLE | gatt.Characteristic.WRITEABLE,
-            b'hello',
-        )
-
-        # Static characteristic with a string value.
-        c2 = gatt.UTF8CharacteristicAdapter(
-            gatt.Characteristic(
-                CHARACTERISTIC_UUID_BASE + "02",
-                gatt.Characteristic.Properties.READ
-                | gatt.Characteristic.Properties.WRITE,
-                gatt.Characteristic.READABLE | gatt.Characteristic.WRITEABLE,
-                'hello',
-            )
-        )
-
-        # Static characteristic with a tuple value.
-        c3 = gatt.PackedCharacteristicAdapter(
-            gatt.Characteristic(
-                CHARACTERISTIC_UUID_BASE + "03",
-                gatt.Characteristic.Properties.READ
-                | gatt.Characteristic.Properties.WRITE,
-                gatt.Characteristic.READABLE | gatt.Characteristic.WRITEABLE,
-                (1007, 1008, 1009),
-            ),
-            ">III",
-        )
-
-        # Static characteristic with a named tuple value.
-        c4 = gatt.MappedCharacteristicAdapter(
-            gatt.Characteristic(
-                CHARACTERISTIC_UUID_BASE + "04",
-                gatt.Characteristic.Properties.READ
-                | gatt.Characteristic.Properties.WRITE,
-                gatt.Characteristic.READABLE | gatt.Characteristic.WRITEABLE,
-                {"f1": 3007, "f2": 3008, "f3": 3009},
-            ),
-            ">III",
-            ["f1", "f2", "f3"],
-        )
-
-        # Static characteristic with a serializable value.
-        c5 = gatt.SerializableCharacteristicAdapter(
-            gatt.Characteristic(
-                CHARACTERISTIC_UUID_BASE + "05",
-                gatt.Characteristic.Properties.READ
-                | gatt.Characteristic.Properties.WRITE,
-                gatt.Characteristic.READABLE | gatt.Characteristic.WRITEABLE,
-                CustomSerializableClass(11, 12),
-            ),
-            CustomSerializableClass,
-        )
-
-        # Static characteristic with a delegated value.
-        c6 = gatt.DelegatedCharacteristicAdapter(
-            gatt.Characteristic(
-                CHARACTERISTIC_UUID_BASE + "06",
-                gatt.Characteristic.Properties.READ
-                | gatt.Characteristic.Properties.WRITE,
-                gatt.Characteristic.READABLE | gatt.Characteristic.WRITEABLE,
-                CustomClass(1, 2),
-            ),
-            encode=CustomClass.encode,
-            decode=CustomClass.decode,
-        )
-
-        # Dynamic characteristic with a bytes value.
-        c7 = gatt.Characteristic(
-            CHARACTERISTIC_UUID_BASE + "07",
-            gatt.Characteristic.Properties.READ | gatt.Characteristic.Properties.WRITE,
-            gatt.Characteristic.READABLE | gatt.Characteristic.WRITEABLE,
-            gatt.CharacteristicValue(
-                read=lambda connection: dynamic_read("bytes"),
-                write=lambda connection, value: dynamic_write("bytes", value),
-            ),
-        )
-
-        # Dynamic characteristic with a string value.
-        c8 = gatt.UTF8CharacteristicAdapter(
-            gatt.Characteristic(
-                CHARACTERISTIC_UUID_BASE + "08",
-                gatt.Characteristic.Properties.READ
-                | gatt.Characteristic.Properties.WRITE,
-                gatt.Characteristic.READABLE | gatt.Characteristic.WRITEABLE,
-                gatt.CharacteristicValue(
-                    read=lambda connection: dynamic_read("string"),
-                    write=lambda connection, value: dynamic_write("string", value),
-                ),
-            )
-        )
-
-        characteristics: List[
-            Union[gatt.Characteristic, gatt.CharacteristicAdapter]
-        ] = [c1, c2, c3, c4, c5, c6, c7, c8]
-
-        # Listen for read and write events.
-        for characteristic in characteristics:
-            characteristic.on(
-                "read",
-                lambda _, value, c=characteristic: on_characteristic_read(c, value),
-            )
-            characteristic.on(
-                "write",
-                lambda _, value, c=characteristic: on_characteristic_write(c, value),
-            )
-
-        device.add_service(gatt.Service(SERVICE_UUID, characteristics))  # type: ignore
-
         # Get things going
         await device.power_on()
 
-        # Connect to a peer
+        if is_client:
-        if len(sys.argv) > 2:
+            # Connect a client to a peer
-            await client(device, hci.Address(sys.argv[2]))
+            await client(device, hci.Address(DEFAULT_SERVER_ADDRESS))
         else:
+            # Advertise so a peer can connect
             await device.start_advertising(auto_restart=True)
 
+            # Setup a server
+            await server(device)
+
         await hci_transport.source.wait_for_termination()
 
 

tests/gatt_service_test.py

@@ -16,6 +16,7 @@
 # Imports
 # -----------------------------------------------------------------------------
 from __future__ import annotations
+import pytest
 
 from . import test_utils
 
@@ -25,6 +26,7 @@ from bumble.profiles import gatt_service
 
 
 # -----------------------------------------------------------------------------
+@pytest.mark.asyncio
 async def test_database_hash():
     devices = await test_utils.TwoDevices.create_with_connection()
     devices[0].gatt_server.services.clear()
@@ -118,6 +120,7 @@ async def test_database_hash():
 
 
 # -----------------------------------------------------------------------------
+@pytest.mark.asyncio
 async def test_service_changed():
     devices = await test_utils.TwoDevices.create_with_connection()
     assert (service := devices[0].gatt_service)

tests/gatt_test.py

@@ -17,32 +17,43 @@
 # -----------------------------------------------------------------------------
 from __future__ import annotations
 import asyncio
+import enum
 import logging
 import os
 import struct
 import pytest
+from typing import Any
 from typing_extensions import Self
 from unittest.mock import AsyncMock, Mock, ANY
 
 from bumble.controller import Controller
-from bumble.gatt_client import CharacteristicProxy
 from bumble.link import LocalLink
 from bumble.device import Device, Peer
 from bumble.host import Host
 from bumble.gatt import (
     GATT_BATTERY_LEVEL_CHARACTERISTIC,
     GATT_CLIENT_CHARACTERISTIC_CONFIGURATION_DESCRIPTOR,
-    CharacteristicAdapter,
-    SerializableCharacteristicAdapter,
-    DelegatedCharacteristicAdapter,
-    PackedCharacteristicAdapter,
-    MappedCharacteristicAdapter,
-    UTF8CharacteristicAdapter,
     Service,
     Characteristic,
     CharacteristicValue,
     Descriptor,
 )
+from bumble.gatt_client import CharacteristicProxy
+from bumble.gatt_adapters import (
+    CharacteristicProxyAdapter,
+    SerializableCharacteristicAdapter,
+    SerializableCharacteristicProxyAdapter,
+    DelegatedCharacteristicAdapter,
+    DelegatedCharacteristicProxyAdapter,
+    PackedCharacteristicAdapter,
+    PackedCharacteristicProxyAdapter,
+    MappedCharacteristicAdapter,
+    MappedCharacteristicProxyAdapter,
+    UTF8CharacteristicAdapter,
+    UTF8CharacteristicProxyAdapter,
+    EnumCharacteristicAdapter,
+    EnumCharacteristicProxyAdapter,
+)
 from bumble.transport import AsyncPipeSink
 from bumble.core import UUID
 from bumble.att import (
@@ -199,7 +210,7 @@ async def test_characteristic_encoding():
     await async_barrier()
     assert characteristic.value == bytes([125])
 
-    cd = DelegatedCharacteristicAdapter(c, encode=lambda x: bytes([x // 2]))
+    cd = DelegatedCharacteristicProxyAdapter(c, encode=lambda x: bytes([x // 2]))
     await cd.write_value(100, with_response=True)
     await async_barrier()
     assert characteristic.value == bytes([50])
@@ -207,7 +218,7 @@ async def test_characteristic_encoding():
     c2 = peer.get_characteristics_by_uuid(async_characteristic.uuid)
     assert len(c2) == 1
     c2 = c2[0]
-    cd2 = PackedCharacteristicAdapter(c2, ">I")
+    cd2 = PackedCharacteristicProxyAdapter(c2, ">I")
     cd2v = await cd2.read_value()
     assert cd2v == 0x05060708
 
@@ -249,7 +260,7 @@ async def test_characteristic_encoding():
     await async_barrier()
     assert last_change is None
 
-    cd = DelegatedCharacteristicAdapter(c, decode=lambda x: x[0])
+    cd = DelegatedCharacteristicProxyAdapter(c, decode=lambda x: x[0])
     await cd.subscribe(on_change)
     await server.notify_subscribers(characteristic)
     await async_barrier()
@@ -314,21 +325,16 @@ async def test_attribute_getters():
 # -----------------------------------------------------------------------------
 @pytest.mark.asyncio
 async def test_CharacteristicAdapter() -> None:
-    # Check that the CharacteristicAdapter base class is transparent
     v = bytes([1, 2, 3])
-    c = Characteristic(
+    c: Characteristic[Any] = Characteristic(
         GATT_BATTERY_LEVEL_CHARACTERISTIC,
         Characteristic.Properties.READ,
         Characteristic.READABLE,
         v,
     )
-    a = CharacteristicAdapter(c)
-
-    value = await a.read_value(None)
-    assert value == v
 
     v = bytes([3, 4, 5])
-    await a.write_value(None, v)
+    await c.write_value(None, v)
     assert c.value == v
 
     # Simple delegated adapter
@@ -415,11 +421,171 @@ async def test_CharacteristicAdapter() -> None:
 
     class_read_value = await class_c.read_value(None)
     assert class_read_value == class_value_bytes
-    c.value = b''
+    class_c.value = b''
     await class_c.write_value(None, class_value_bytes)
-    assert isinstance(c.value, BlaBla)
+    assert isinstance(class_c.value, BlaBla)
-    assert c.value.a == 3
+    assert class_c.value.a == class_value.a
-    assert c.value.b == 4
+    assert class_c.value.b == class_value.b
+
+    # Enum adapter
+    class MyEnum(enum.IntEnum):
+        ENUM_1 = 1234
+        ENUM_2 = 5678
+
+    enum_value = MyEnum.ENUM_2
+    enum_value_bytes = int(enum_value).to_bytes(3, 'big')
+    c.value = enum_value
+    enum_c = EnumCharacteristicAdapter(c, MyEnum, 3, 'big')
+    enum_read_value = await enum_c.read_value(None)
+    assert enum_read_value == enum_value_bytes
+    enum_c.value = b''
+    await enum_c.write_value(None, enum_value_bytes)
+    assert isinstance(enum_c.value, MyEnum)
+    assert enum_c.value == enum_value
+
+
+# -----------------------------------------------------------------------------
+@pytest.mark.asyncio
+async def test_CharacteristicProxyAdapter() -> None:
+    class Client:
+        def __init__(self, value):
+            self.value = value
+
+        async def read_value(self, handle, no_long_read=False) -> bytes:
+            return self.value
+
+        async def write_value(self, handle, value, with_response=False):
+            self.value = value
+
+    class TestAttributeProxy(CharacteristicProxy):
+        def __init__(self, value) -> None:
+            super().__init__(Client(value), 0, 0, None, 0)  # type: ignore
+
+        @property
+        def value(self):
+            return self.client.value
+
+        @value.setter
+        def value(self, value):
+            self.client.value = value
+
+    v = bytes([1, 2, 3])
+    c = TestAttributeProxy(v)
+    a: CharacteristicProxyAdapter = CharacteristicProxyAdapter(c)
+
+    value = await a.read_value()
+    assert value == v
+
+    v = bytes([3, 4, 5])
+    await a.write_value(v)
+    assert c.value == v
+
+    # Simple delegated adapter
+    delegated = DelegatedCharacteristicProxyAdapter(
+        c, lambda x: bytes(reversed(x)), lambda x: bytes(reversed(x))
+    )
+
+    delegated_value = await delegated.read_value()
+    assert delegated_value == bytes(reversed(v))
+
+    delegated_value2 = bytes([3, 4, 5])
+    await delegated.write_value(delegated_value2)
+    assert c.value == bytes(reversed(delegated_value2))
+
+    # Packed adapter with single element format
+    packed_value_ref = 1234
+    packed_value_bytes = struct.pack('>H', packed_value_ref)
+    c.value = packed_value_bytes
+    packed = PackedCharacteristicProxyAdapter(c, '>H')
+
+    packed_value_read = await packed.read_value()
+    assert packed_value_read == packed_value_ref
+    c.value = None
+    await packed.write_value(packed_value_ref)
+    assert c.value == packed_value_bytes
+
+    # Packed adapter with multi-element format
+    v1 = 1234
+    v2 = 5678
+    packed_multi_value_bytes = struct.pack('>HH', v1, v2)
+    c.value = packed_multi_value_bytes
+    packed_multi = PackedCharacteristicProxyAdapter(c, '>HH')
+
+    packed_multi_read_value = await packed_multi.read_value()
+    assert packed_multi_read_value == (v1, v2)
+    c.value = b''
+    await packed_multi.write_value((v1, v2))
+    assert c.value == packed_multi_value_bytes
+
+    # Mapped adapter
+    v1 = 1234
+    v2 = 5678
+    packed_mapped_value_bytes = struct.pack('>HH', v1, v2)
+    mapped = {'v1': v1, 'v2': v2}
+    c.value = packed_mapped_value_bytes
+    packed_mapped = MappedCharacteristicProxyAdapter(c, '>HH', ('v1', 'v2'))
+
+    packed_mapped_read_value = await packed_mapped.read_value()
+    assert packed_mapped_read_value == mapped
+    c.value = b''
+    await packed_mapped.write_value(mapped)
+    assert c.value == packed_mapped_value_bytes
+
+    # UTF-8 adapter
+    string_value = 'Hello π'
+    string_value_bytes = string_value.encode('utf-8')
+    c.value = string_value_bytes
+    string_c = UTF8CharacteristicProxyAdapter(c)
+
+    string_read_value = await string_c.read_value()
+    assert string_read_value == string_value
+    c.value = b''
+    await string_c.write_value(string_value)
+    assert c.value == string_value_bytes
+
+    # Class adapter
+    class BlaBla:
+        def __init__(self, a: int, b: int) -> None:
+            self.a = a
+            self.b = b
+
+        @classmethod
+        def from_bytes(cls, data: bytes) -> Self:
+            a, b = struct.unpack(">II", data)
+            return cls(a, b)
+
+        def __bytes__(self) -> bytes:
+            return struct.pack(">II", self.a, self.b)
+
+    class_value = BlaBla(3, 4)
+    class_value_bytes = struct.pack(">II", 3, 4)
+    c.value = class_value_bytes
+    class_c = SerializableCharacteristicProxyAdapter(c, BlaBla)
+
+    class_read_value = await class_c.read_value()
+    assert isinstance(class_read_value, BlaBla)
+    assert class_read_value.a == class_value.a
+    assert class_read_value.b == class_value.b
+    c.value = b''
+    await class_c.write_value(class_value)
+    assert c.value == class_value_bytes
+
+    # Enum adapter
+    class MyEnum(enum.IntEnum):
+        ENUM_1 = 1234
+        ENUM_2 = 5678
+
+    enum_value = MyEnum.ENUM_1
+    enum_value_bytes = int(enum_value).to_bytes(3, 'little')
+    c.value = enum_value_bytes
+    enum_c = EnumCharacteristicProxyAdapter(c, MyEnum, 3)
+
+    enum_read_value = await enum_c.read_value()
+    assert isinstance(enum_read_value, MyEnum)
+    assert enum_read_value == enum_value
+    c.value = b''
+    await enum_c.write_value(enum_value)
+    assert c.value == enum_value_bytes
 
 
 # -----------------------------------------------------------------------------
@@ -601,7 +767,7 @@ async def test_read_write2():
     v1 = await c1.read_value()
     assert v1 == v
 
-    a1 = PackedCharacteristicAdapter(c1, '>I')
+    a1 = PackedCharacteristicProxyAdapter(c1, '>I')
     v1 = await a1.read_value()
     assert v1 == struct.unpack('>I', v)[0]
 
@@ -1114,6 +1280,7 @@ async def async_main():
     await test_CharacteristicValue()
     await test_CharacteristicValue_async()
     await test_CharacteristicAdapter()
+    await test_CharacteristicProxyAdapter()
 
 
 # -----------------------------------------------------------------------------

tests/gmap_test.py

@@ -78,7 +78,11 @@ async def test_init_service(gmap_client: GamingAudioServiceProxy):
         | GmapRole.BROADCAST_GAME_RECEIVER
         | GmapRole.BROADCAST_GAME_SENDER
     )
+    assert gmap_client.ugg_features is not None
     assert await gmap_client.ugg_features.read_value() == UggFeatures.UGG_MULTISINK
+    assert gmap_client.ugt_features is not None
     assert await gmap_client.ugt_features.read_value() == UgtFeatures.UGT_SOURCE
+    assert gmap_client.bgr_features is not None
     assert await gmap_client.bgr_features.read_value() == BgrFeatures.BGR_MULTISINK
+    assert gmap_client.bgs_features is not None
     assert await gmap_client.bgs_features.read_value() == BgsFeatures.BGS_96_KBPS