diff --git a/compatibility_matrices/compatibility_matrix.202504.xml b/compatibility_matrices/compatibility_matrix.202504.xml
index 5589e54..cd8fe2d 100644
--- a/compatibility_matrices/compatibility_matrix.202504.xml
+++ b/compatibility_matrices/compatibility_matrix.202504.xml
@@ -194,7 +194,7 @@
     </hal>
     <hal format="aidl">
         <name>android.hardware.contexthub</name>
-        <version>3</version>
+        <version>3-4</version>
         <interface>
             <name>IContextHub</name>
             <instance>default</instance>
diff --git a/contexthub/aidl/Android.bp b/contexthub/aidl/Android.bp
index 202813c..eaa47c6 100644
--- a/contexthub/aidl/Android.bp
+++ b/contexthub/aidl/Android.bp
@@ -52,8 +52,6 @@
             version: "3",
             imports: [],
         },
-
     ],
-    frozen: true,
-
+    frozen: false,
 }
diff --git a/contexthub/aidl/aidl_api/android.hardware.contexthub/current/android/hardware/contexthub/EndpointId.aidl b/contexthub/aidl/aidl_api/android.hardware.contexthub/current/android/hardware/contexthub/EndpointId.aidl
new file mode 100644
index 0000000..a70065d
--- /dev/null
+++ b/contexthub/aidl/aidl_api/android.hardware.contexthub/current/android/hardware/contexthub/EndpointId.aidl
@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * 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
+ *
+ *      http://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.
+ */
+///////////////////////////////////////////////////////////////////////////////
+// THIS FILE IS IMMUTABLE. DO NOT EDIT IN ANY CASE.                          //
+///////////////////////////////////////////////////////////////////////////////
+
+// This file is a snapshot of an AIDL file. Do not edit it manually. There are
+// two cases:
+// 1). this is a frozen version file - do not edit this in any case.
+// 2). this is a 'current' file. If you make a backwards compatible change to
+//     the interface (from the latest frozen version), the build system will
+//     prompt you to update this file with `m <name>-update-api`.
+//
+// You must not make a backward incompatible change to any AIDL file built
+// with the aidl_interface module type with versions property set. The module
+// type is used to build AIDL files in a way that they can be used across
+// independently updatable components of the system. If a device is shipped
+// with such a backward incompatible change, it has a high risk of breaking
+// later when a module using the interface is updated, e.g., Mainline modules.
+
+package android.hardware.contexthub;
+@VintfStability
+parcelable EndpointId {
+  long id;
+  long hubId;
+  const long ENDPOINT_ID_INVALID = 0;
+  const long ENDPOINT_ID_RESERVED = (-1) /* -1 */;
+}
diff --git a/contexthub/aidl/aidl_api/android.hardware.contexthub/current/android/hardware/contexthub/EndpointInfo.aidl b/contexthub/aidl/aidl_api/android.hardware.contexthub/current/android/hardware/contexthub/EndpointInfo.aidl
new file mode 100644
index 0000000..43e5ec3
--- /dev/null
+++ b/contexthub/aidl/aidl_api/android.hardware.contexthub/current/android/hardware/contexthub/EndpointInfo.aidl
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * 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
+ *
+ *      http://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.
+ */
+///////////////////////////////////////////////////////////////////////////////
+// THIS FILE IS IMMUTABLE. DO NOT EDIT IN ANY CASE.                          //
+///////////////////////////////////////////////////////////////////////////////
+
+// This file is a snapshot of an AIDL file. Do not edit it manually. There are
+// two cases:
+// 1). this is a frozen version file - do not edit this in any case.
+// 2). this is a 'current' file. If you make a backwards compatible change to
+//     the interface (from the latest frozen version), the build system will
+//     prompt you to update this file with `m <name>-update-api`.
+//
+// You must not make a backward incompatible change to any AIDL file built
+// with the aidl_interface module type with versions property set. The module
+// type is used to build AIDL files in a way that they can be used across
+// independently updatable components of the system. If a device is shipped
+// with such a backward incompatible change, it has a high risk of breaking
+// later when a module using the interface is updated, e.g., Mainline modules.
+
+package android.hardware.contexthub;
+@VintfStability
+parcelable EndpointInfo {
+  android.hardware.contexthub.EndpointId id;
+  android.hardware.contexthub.EndpointInfo.EndpointType type;
+  String name;
+  int version;
+  @nullable String tag;
+  String[] requiredPermissions;
+  android.hardware.contexthub.Service[] services;
+  @Backing(type="int") @VintfStability
+  enum EndpointType {
+    FRAMEWORK = 1,
+    APP = 2,
+    NATIVE = 3,
+    NANOAPP = 4,
+    GENERIC = 5,
+  }
+}
diff --git a/contexthub/aidl/aidl_api/android.hardware.contexthub/current/android/hardware/contexthub/HubInfo.aidl b/contexthub/aidl/aidl_api/android.hardware.contexthub/current/android/hardware/contexthub/HubInfo.aidl
new file mode 100644
index 0000000..cac441a
--- /dev/null
+++ b/contexthub/aidl/aidl_api/android.hardware.contexthub/current/android/hardware/contexthub/HubInfo.aidl
@@ -0,0 +1,45 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * 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
+ *
+ *      http://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.
+ */
+///////////////////////////////////////////////////////////////////////////////
+// THIS FILE IS IMMUTABLE. DO NOT EDIT IN ANY CASE.                          //
+///////////////////////////////////////////////////////////////////////////////
+
+// This file is a snapshot of an AIDL file. Do not edit it manually. There are
+// two cases:
+// 1). this is a frozen version file - do not edit this in any case.
+// 2). this is a 'current' file. If you make a backwards compatible change to
+//     the interface (from the latest frozen version), the build system will
+//     prompt you to update this file with `m <name>-update-api`.
+//
+// You must not make a backward incompatible change to any AIDL file built
+// with the aidl_interface module type with versions property set. The module
+// type is used to build AIDL files in a way that they can be used across
+// independently updatable components of the system. If a device is shipped
+// with such a backward incompatible change, it has a high risk of breaking
+// later when a module using the interface is updated, e.g., Mainline modules.
+
+package android.hardware.contexthub;
+@VintfStability
+parcelable HubInfo {
+  long hubId;
+  android.hardware.contexthub.HubInfo.HubDetails hubDetails;
+  const long HUB_ID_INVALID = 0;
+  const long HUB_ID_RESERVED = (-1) /* -1 */;
+  union HubDetails {
+    android.hardware.contexthub.ContextHubInfo contextHubInfo;
+    android.hardware.contexthub.VendorHubInfo vendorHubInfo;
+  }
+}
diff --git a/contexthub/aidl/aidl_api/android.hardware.contexthub/current/android/hardware/contexthub/IContextHub.aidl b/contexthub/aidl/aidl_api/android.hardware.contexthub/current/android/hardware/contexthub/IContextHub.aidl
index 7341e0e..93b8ff5 100644
--- a/contexthub/aidl/aidl_api/android.hardware.contexthub/current/android/hardware/contexthub/IContextHub.aidl
+++ b/contexthub/aidl/aidl_api/android.hardware.contexthub/current/android/hardware/contexthub/IContextHub.aidl
@@ -49,5 +49,16 @@
   void onNanSessionStateChanged(in android.hardware.contexthub.NanSessionStateUpdate update);
   void setTestMode(in boolean enable);
   void sendMessageDeliveryStatusToHub(in int contextHubId, in android.hardware.contexthub.MessageDeliveryStatus messageDeliveryStatus);
+  List<android.hardware.contexthub.HubInfo> getHubs();
+  List<android.hardware.contexthub.EndpointInfo> getEndpoints();
+  void registerEndpoint(in android.hardware.contexthub.EndpointInfo endpoint);
+  void unregisterEndpoint(in android.hardware.contexthub.EndpointInfo endpoint);
+  void registerEndpointCallback(in android.hardware.contexthub.IEndpointCallback callback);
+  int[] requestSessionIdRange(int size);
+  void openEndpointSession(int sessionId, in android.hardware.contexthub.EndpointId destination, in android.hardware.contexthub.EndpointId initiator, in @nullable String serviceDescriptor);
+  void sendMessageToEndpoint(int sessionId, in android.hardware.contexthub.Message msg);
+  void sendMessageDeliveryStatusToEndpoint(int sessionId, in android.hardware.contexthub.MessageDeliveryStatus msgStatus);
+  void closeEndpointSession(int sessionId, in android.hardware.contexthub.Reason reason);
+  void endpointSessionOpenComplete(int sessionId);
   const int EX_CONTEXT_HUB_UNSPECIFIED = (-1) /* -1 */;
 }
diff --git a/contexthub/aidl/aidl_api/android.hardware.contexthub/current/android/hardware/contexthub/IEndpointCallback.aidl b/contexthub/aidl/aidl_api/android.hardware.contexthub/current/android/hardware/contexthub/IEndpointCallback.aidl
new file mode 100644
index 0000000..c0bb744
--- /dev/null
+++ b/contexthub/aidl/aidl_api/android.hardware.contexthub/current/android/hardware/contexthub/IEndpointCallback.aidl
@@ -0,0 +1,44 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * 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
+ *
+ *      http://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.
+ */
+///////////////////////////////////////////////////////////////////////////////
+// THIS FILE IS IMMUTABLE. DO NOT EDIT IN ANY CASE.                          //
+///////////////////////////////////////////////////////////////////////////////
+
+// This file is a snapshot of an AIDL file. Do not edit it manually. There are
+// two cases:
+// 1). this is a frozen version file - do not edit this in any case.
+// 2). this is a 'current' file. If you make a backwards compatible change to
+//     the interface (from the latest frozen version), the build system will
+//     prompt you to update this file with `m <name>-update-api`.
+//
+// You must not make a backward incompatible change to any AIDL file built
+// with the aidl_interface module type with versions property set. The module
+// type is used to build AIDL files in a way that they can be used across
+// independently updatable components of the system. If a device is shipped
+// with such a backward incompatible change, it has a high risk of breaking
+// later when a module using the interface is updated, e.g., Mainline modules.
+
+package android.hardware.contexthub;
+@VintfStability
+interface IEndpointCallback {
+  void onEndpointStarted(in android.hardware.contexthub.EndpointInfo[] endpointInfos);
+  void onEndpointStopped(in android.hardware.contexthub.EndpointId[] endpointIds, android.hardware.contexthub.Reason reason);
+  void onMessageReceived(int sessionId, in android.hardware.contexthub.Message msg);
+  void onMessageDeliveryStatusReceived(int sessionId, in android.hardware.contexthub.MessageDeliveryStatus msgStatus);
+  void onEndpointSessionOpenRequest(int sessionId, in android.hardware.contexthub.EndpointId destination, in android.hardware.contexthub.EndpointId initiator, in @nullable String serviceDescriptor);
+  void onCloseEndpointSession(int sessionId, in android.hardware.contexthub.Reason reason);
+  void onEndpointSessionOpenComplete(int sessionId);
+}
diff --git a/contexthub/aidl/aidl_api/android.hardware.contexthub/current/android/hardware/contexthub/Message.aidl b/contexthub/aidl/aidl_api/android.hardware.contexthub/current/android/hardware/contexthub/Message.aidl
new file mode 100644
index 0000000..ef117c3
--- /dev/null
+++ b/contexthub/aidl/aidl_api/android.hardware.contexthub/current/android/hardware/contexthub/Message.aidl
@@ -0,0 +1,43 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * 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
+ *
+ *      http://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.
+ */
+///////////////////////////////////////////////////////////////////////////////
+// THIS FILE IS IMMUTABLE. DO NOT EDIT IN ANY CASE.                          //
+///////////////////////////////////////////////////////////////////////////////
+
+// This file is a snapshot of an AIDL file. Do not edit it manually. There are
+// two cases:
+// 1). this is a frozen version file - do not edit this in any case.
+// 2). this is a 'current' file. If you make a backwards compatible change to
+//     the interface (from the latest frozen version), the build system will
+//     prompt you to update this file with `m <name>-update-api`.
+//
+// You must not make a backward incompatible change to any AIDL file built
+// with the aidl_interface module type with versions property set. The module
+// type is used to build AIDL files in a way that they can be used across
+// independently updatable components of the system. If a device is shipped
+// with such a backward incompatible change, it has a high risk of breaking
+// later when a module using the interface is updated, e.g., Mainline modules.
+
+package android.hardware.contexthub;
+@VintfStability
+parcelable Message {
+  int flags;
+  int sequenceNumber;
+  String[] permissions;
+  int type;
+  byte[] content;
+  const int FLAG_REQUIRES_DELIVERY_STATUS = 1;
+}
diff --git a/contexthub/aidl/aidl_api/android.hardware.contexthub/current/android/hardware/contexthub/Reason.aidl b/contexthub/aidl/aidl_api/android.hardware.contexthub/current/android/hardware/contexthub/Reason.aidl
new file mode 100644
index 0000000..a315438
--- /dev/null
+++ b/contexthub/aidl/aidl_api/android.hardware.contexthub/current/android/hardware/contexthub/Reason.aidl
@@ -0,0 +1,46 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * 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
+ *
+ *      http://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.
+ */
+///////////////////////////////////////////////////////////////////////////////
+// THIS FILE IS IMMUTABLE. DO NOT EDIT IN ANY CASE.                          //
+///////////////////////////////////////////////////////////////////////////////
+
+// This file is a snapshot of an AIDL file. Do not edit it manually. There are
+// two cases:
+// 1). this is a frozen version file - do not edit this in any case.
+// 2). this is a 'current' file. If you make a backwards compatible change to
+//     the interface (from the latest frozen version), the build system will
+//     prompt you to update this file with `m <name>-update-api`.
+//
+// You must not make a backward incompatible change to any AIDL file built
+// with the aidl_interface module type with versions property set. The module
+// type is used to build AIDL files in a way that they can be used across
+// independently updatable components of the system. If a device is shipped
+// with such a backward incompatible change, it has a high risk of breaking
+// later when a module using the interface is updated, e.g., Mainline modules.
+
+package android.hardware.contexthub;
+@Backing(type="byte") @VintfStability
+enum Reason {
+  UNSPECIFIED = 0,
+  OUT_OF_MEMORY,
+  TIMEOUT,
+  OPEN_ENDPOINT_SESSION_REQUEST_REJECTED,
+  CLOSE_ENDPOINT_SESSION_REQUESTED,
+  ENDPOINT_INVALID,
+  ENDPOINT_GONE,
+  ENDPOINT_CRASHED,
+  HUB_RESET,
+}
diff --git a/contexthub/aidl/aidl_api/android.hardware.contexthub/current/android/hardware/contexthub/Service.aidl b/contexthub/aidl/aidl_api/android.hardware.contexthub/current/android/hardware/contexthub/Service.aidl
new file mode 100644
index 0000000..e3d94c8
--- /dev/null
+++ b/contexthub/aidl/aidl_api/android.hardware.contexthub/current/android/hardware/contexthub/Service.aidl
@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * 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
+ *
+ *      http://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.
+ */
+///////////////////////////////////////////////////////////////////////////////
+// THIS FILE IS IMMUTABLE. DO NOT EDIT IN ANY CASE.                          //
+///////////////////////////////////////////////////////////////////////////////
+
+// This file is a snapshot of an AIDL file. Do not edit it manually. There are
+// two cases:
+// 1). this is a frozen version file - do not edit this in any case.
+// 2). this is a 'current' file. If you make a backwards compatible change to
+//     the interface (from the latest frozen version), the build system will
+//     prompt you to update this file with `m <name>-update-api`.
+//
+// You must not make a backward incompatible change to any AIDL file built
+// with the aidl_interface module type with versions property set. The module
+// type is used to build AIDL files in a way that they can be used across
+// independently updatable components of the system. If a device is shipped
+// with such a backward incompatible change, it has a high risk of breaking
+// later when a module using the interface is updated, e.g., Mainline modules.
+
+package android.hardware.contexthub;
+@VintfStability
+parcelable Service {
+  android.hardware.contexthub.Service.RpcFormat format;
+  String serviceDescriptor;
+  int majorVersion;
+  int minorVersion;
+  ParcelableHolder extendedInfo;
+  @Backing(type="int") @VintfStability
+  enum RpcFormat {
+    CUSTOM = 0,
+    AIDL = 1,
+    PW_RPC_PROTOBUF = 2,
+  }
+}
diff --git a/contexthub/aidl/aidl_api/android.hardware.contexthub/current/android/hardware/contexthub/VendorHubInfo.aidl b/contexthub/aidl/aidl_api/android.hardware.contexthub/current/android/hardware/contexthub/VendorHubInfo.aidl
new file mode 100644
index 0000000..db64ec7
--- /dev/null
+++ b/contexthub/aidl/aidl_api/android.hardware.contexthub/current/android/hardware/contexthub/VendorHubInfo.aidl
@@ -0,0 +1,40 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * 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
+ *
+ *      http://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.
+ */
+///////////////////////////////////////////////////////////////////////////////
+// THIS FILE IS IMMUTABLE. DO NOT EDIT IN ANY CASE.                          //
+///////////////////////////////////////////////////////////////////////////////
+
+// This file is a snapshot of an AIDL file. Do not edit it manually. There are
+// two cases:
+// 1). this is a frozen version file - do not edit this in any case.
+// 2). this is a 'current' file. If you make a backwards compatible change to
+//     the interface (from the latest frozen version), the build system will
+//     prompt you to update this file with `m <name>-update-api`.
+//
+// You must not make a backward incompatible change to any AIDL file built
+// with the aidl_interface module type with versions property set. The module
+// type is used to build AIDL files in a way that they can be used across
+// independently updatable components of the system. If a device is shipped
+// with such a backward incompatible change, it has a high risk of breaking
+// later when a module using the interface is updated, e.g., Mainline modules.
+
+package android.hardware.contexthub;
+@VintfStability
+parcelable VendorHubInfo {
+  String name;
+  int version;
+  ParcelableHolder extendedInfo;
+}
diff --git a/contexthub/aidl/android/hardware/contexthub/EndpointId.aidl b/contexthub/aidl/android/hardware/contexthub/EndpointId.aidl
new file mode 100644
index 0000000..2075e73
--- /dev/null
+++ b/contexthub/aidl/android/hardware/contexthub/EndpointId.aidl
@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * 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
+ *
+ *      http://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.
+ */
+
+package android.hardware.contexthub;
+
+/* This structure is a unique identifier for an endpoint */
+@VintfStability
+parcelable EndpointId {
+    /**
+     * Invalid endpoint ID.
+     */
+    const long ENDPOINT_ID_INVALID = 0;
+
+    /**
+     * Reserved endpoint ID.
+     */
+    const long ENDPOINT_ID_RESERVED = -1;
+
+    /**
+     * Nanoapp ID or randomly generated ID (depending on type). This value uniquely identifies the
+     * endpoint within a single hub.
+     *
+     * ENDPOINT_ID_INVALID(0) is an invalid id and should never be used.
+     * ENDPOINT_ID_RESERVED(-1) is reserved for future use.
+     * For static/compile-time-generated IDs, topmost bit should be 0.
+     * For dynamic/runtime-generated IDs, topmost bit should be 1.
+     */
+    long id;
+
+    /**
+     * Hub ID of the hub hosting this endpoint. A pair of (hubId, id) uniquely identifies the
+     * endpoint globally.
+     */
+    long hubId;
+}
diff --git a/contexthub/aidl/android/hardware/contexthub/EndpointInfo.aidl b/contexthub/aidl/android/hardware/contexthub/EndpointInfo.aidl
new file mode 100644
index 0000000..53a41fc
--- /dev/null
+++ b/contexthub/aidl/android/hardware/contexthub/EndpointInfo.aidl
@@ -0,0 +1,101 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * 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
+ *
+ *      http://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.
+ */
+
+package android.hardware.contexthub;
+
+import android.hardware.contexthub.EndpointId;
+import android.hardware.contexthub.Service;
+
+/* This structure is a unified superset of NanoAppInfo and HostEndpointInfo. */
+@VintfStability
+parcelable EndpointInfo {
+    /** Unique identifier of this endpoint. */
+    EndpointId id;
+
+    /** Type of this endpoint. */
+    EndpointType type;
+
+    /**
+     * Name of this endpoint. Endpoint may use this field to identify the initiator of the session
+     * request.
+     *
+     * Depending on type of the endpoint, the following values are used:
+     *  - Framework: package name of the process registering this endpoint
+     *  - App: package name of the process registering this endpoint
+     *  - Native: name of the process registering this endpoint, supplied by client for debugging
+     *            purpose.
+     *  - Nanoapp: name of the nanoapp, for debugging purpose
+     *  - Generic: name of the generic endpoint, for debugging purpose
+     */
+    String name;
+
+    /**
+     * Monotonically increasing version number. The two sides of an endpoint session can use this
+     * version number to identify the other side and determine compatibility with each other.
+     * The interpretation of the version number is specific to the implementation of an endpoint.
+     * The version number should not be used to compare endpoints implementation freshness for
+     * different endpoint types.
+     *
+     * Depending on type of the endpoint, the following values are used:
+     *  - Framework: android.os.Build.VERSION.SDK_INT_FULL (populated by ContextHubService)
+     *  - App: versionCode (populated by ContextHubService)
+     *  - Native: unspecified format (supplied by endpoint code)
+     *  - Nanoapp: nanoapp version, typically following 0xMMmmpppp scheme where
+     *             MM = major version, mm = minor version, pppp = patch version
+     *  - Generic: unspecified format (supplied by endpoint code), following nanoapp versioning
+     *             scheme is recommended
+     */
+    int version;
+
+    /**
+     * Tag for this particular endpoint. Optional string that further identifies the submodule
+     * that created this endpoint.
+     */
+    @nullable String tag;
+
+    /**
+     * Represents the minimally required permissions in order to message this endpoint. Further
+     * permissions may be required on a message-by-message basis.
+     */
+    String[] requiredPermissions;
+
+    /**
+     * List of services provided by this endpoint. Service list should be fixed for the
+     * lifetime of an endpoint.
+     */
+    Service[] services;
+
+    @VintfStability
+    @Backing(type="int")
+    enum EndpointType {
+        /**
+         * This endpoint is from the Android framework
+         */
+        FRAMEWORK = 1,
+
+        /** This endpoint is an Android app. */
+        APP = 2,
+
+        /** This endpoint is from an Android native program. */
+        NATIVE = 3,
+
+        /** This endpoint is from a nanoapp. */
+        NANOAPP = 4,
+
+        /** This endpoint is a generic endpoint (not from a nanoapp). */
+        GENERIC = 5,
+    }
+}
diff --git a/contexthub/aidl/android/hardware/contexthub/HubInfo.aidl b/contexthub/aidl/android/hardware/contexthub/HubInfo.aidl
new file mode 100644
index 0000000..3d0a76e
--- /dev/null
+++ b/contexthub/aidl/android/hardware/contexthub/HubInfo.aidl
@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * 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
+ *
+ *      http://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.
+ */
+
+package android.hardware.contexthub;
+
+import android.hardware.contexthub.ContextHubInfo;
+import android.hardware.contexthub.VendorHubInfo;
+
+@VintfStability
+parcelable HubInfo {
+    /**
+     * Invalid hub ID.
+     */
+    const long HUB_ID_INVALID = 0;
+
+    /**
+     * Reserved hub ID.
+     */
+    const long HUB_ID_RESERVED = -1;
+
+    /**
+     * Hub ID (depending on type). This is a globally unique identifier.
+     *
+     * HUB_ID_INVALID(0) is an invalid id and should never be used.
+     * HUB_ID_RESERVED(-1) is reserved for future use.
+     */
+    long hubId;
+
+    /**
+     * A hub can be either a ContextHub or a VendorHub.
+     */
+    union HubDetails {
+        ContextHubInfo contextHubInfo;
+        VendorHubInfo vendorHubInfo;
+    }
+
+    /**
+     * Detail information about the hub.
+     */
+    HubDetails hubDetails;
+}
diff --git a/contexthub/aidl/android/hardware/contexthub/IContextHub.aidl b/contexthub/aidl/android/hardware/contexthub/IContextHub.aidl
index b146ff8..24192a1 100644
--- a/contexthub/aidl/android/hardware/contexthub/IContextHub.aidl
+++ b/contexthub/aidl/android/hardware/contexthub/IContextHub.aidl
@@ -18,12 +18,19 @@
 
 import android.hardware.contexthub.ContextHubInfo;
 import android.hardware.contexthub.ContextHubMessage;
+import android.hardware.contexthub.EndpointId;
+import android.hardware.contexthub.EndpointInfo;
 import android.hardware.contexthub.HostEndpointInfo;
+import android.hardware.contexthub.HubInfo;
 import android.hardware.contexthub.IContextHubCallback;
+import android.hardware.contexthub.IEndpointCallback;
+import android.hardware.contexthub.Message;
 import android.hardware.contexthub.MessageDeliveryStatus;
 import android.hardware.contexthub.NanSessionStateUpdate;
 import android.hardware.contexthub.NanoappBinary;
 import android.hardware.contexthub.NanoappInfo;
+import android.hardware.contexthub.Reason;
+import android.hardware.contexthub.Service;
 import android.hardware.contexthub.Setting;
 
 @VintfStability
@@ -221,7 +228,7 @@
     void onNanSessionStateChanged(in NanSessionStateUpdate update);
 
     /**
-     * Puts the context hub in and out of test mode. Test mode is a clean state
+     * Puts the Context Hub in and out of test mode. Test mode is a clean state
      * where tests can be executed in the same environment. If enable is true,
      * this will enable test mode by unloading all nanoapps. If enable is false,
      * this will disable test mode and reverse the actions of enabling test mode
@@ -231,7 +238,7 @@
      * @TestApi or development tools. This should not be used in a production
      * environment.
      *
-     * @param enable If true, put the context hub in test mode. If false, disable
+     * @param enable If true, put the Context Hub in test mode. If false, disable
      *               test mode.
      */
     void setTestMode(in boolean enable);
@@ -256,4 +263,136 @@
      * value EX_SERVICE_SPECIFIC.
      */
     const int EX_CONTEXT_HUB_UNSPECIFIED = -1;
+
+    /** Lists all the hubs, including the Context Hub and generic hubs. */
+    List<HubInfo> getHubs();
+
+    /** Lists all the endpoints, including the Context Hub nanoapps and generic endpoints. */
+    List<EndpointInfo> getEndpoints();
+
+    /**
+     * Publishes an endpoint from the calling side (e.g. Android). Endpoints must be registered
+     * prior to starting a session.
+     */
+    void registerEndpoint(in EndpointInfo endpoint);
+
+    /**
+     * Teardown an endpoint from the calling side (e.g. Android). This endpoint must have already
+     * been published via registerEndpoint().
+     */
+    void unregisterEndpoint(in EndpointInfo endpoint);
+
+    /**
+     * Attaches a callback interface to receive events targeted at endpoints registered by the
+     * caller.
+     */
+    void registerEndpointCallback(in IEndpointCallback callback);
+
+    /**
+     * Request a range of session IDs for the caller to use when initiating sessions. This may be
+     * called more than once, but typical usage is to request a large enough range to accommodate
+     * the maximum expected number of concurrent sessions, but not overly large as to limit other
+     * clients.
+     *
+     * @param size The number of sessionId reserved for host-initiated sessions. This number should
+     *         be less than or equal to 1024.
+     *
+     * @return An array with two elements representing the smallest and largest possible session id
+     *         available for host.
+     *
+     * @throws EX_ILLEGAL_ARGUMENT if the size is invalid.
+     * @throws EX_SERVICE_SPECIFIC if the id range requested cannot be allocated.
+     */
+    int[] requestSessionIdRange(int size);
+
+    /**
+     * Request to open a session for communication between an endpoint previously registered by the
+     * caller and a target endpoint found in getEndpoints(), optionally scoped to a service
+     * published by the target endpoint.
+     *
+     * Upon returning from this function, the session is in pending state, and the final result will
+     * be given by an asynchronous call to onEndpointSessionOpenComplete() on success, or
+     * onCloseEndpointSession() on failure.
+     *
+     * @param sessionId Caller-allocated session identifier, which must be unique across all active
+     *         sessions, and must fall in a range allocated via requestSessionIdRange().
+     * @param destination The EndpointId representing the destination side of the session.
+     * @param initiator The EndpointId representing the initiating side of the session, which
+     *         must've already been published through registerEndpoint().
+     * @param serviceDescriptor Descriptor for the service specification for scoping this session
+     *         (nullable). Null indicates a fully custom marshalling scheme. The value should match
+     *         a published descriptor for both destination and initiator.
+     *
+     * @return An integer identifying the session, the integer can be used to present
+     *         the tuple of (destination, initiator, serviceDescriptor).
+     *
+     * @throws EX_ILLEGAL_ARGUMENT if any of the arguments are invalid, or the combination of the
+     *         arguments is invalid.
+     * @throws EX_SERVICE_SPECIFIC on other errors
+     *         - EX_CONTEXT_HUB_UNSPECIFIED if the request failed for other reasons.
+     */
+    void openEndpointSession(int sessionId, in EndpointId destination, in EndpointId initiator,
+            in @nullable String serviceDescriptor);
+
+    /**
+     * Send a message from one endpoint to another on the (currently open) session.
+     *
+     * @param sessionId The integer representing the communication session, previously set in
+     *         openEndpointSession() or onEndpointSessionOpenRequest().
+     * @param msg The Message object representing a message to endpoint from the endpoint on host.
+     *
+     * @throws EX_ILLEGAL_ARGUMENT if any of the arguments are invalid, or the combination of the
+     *         arguments is invalid.
+     * @throws EX_SERVICE_SPECIFIC on other errors
+     *         - EX_CONTEXT_HUB_UNSPECIFIED if the request failed for other reasons.
+     */
+    void sendMessageToEndpoint(int sessionId, in Message msg);
+
+    /**
+     * Sends a message delivery status to the endpoint in response to receiving a Message with flag
+     * FLAG_REQUIRES_DELIVERY_STATUS. Each message with the flag should have a MessageDeliveryStatus
+     * response. This method sends the message delivery status back to the remote endpoint for a
+     * session.
+     *
+     * @param sessionId The integer representing the communication session, previously set in
+     *         openEndpointSession() or onEndpointSessionOpenRequest().
+     * @param msgStatus The MessageDeliveryStatus object representing the delivery status for a
+     *         specific message (identified by the sequenceNumber) within the session.
+     *
+     * @throws EX_UNSUPPORTED_OPERATION if ContextHubInfo.supportsReliableMessages is false for
+     *          the hub involved in this session.
+     */
+    void sendMessageDeliveryStatusToEndpoint(int sessionId, in MessageDeliveryStatus msgStatus);
+
+    /**
+     * Closes a session previously opened by openEndpointSession() or requested via
+     * onEndpointSessionOpenRequest(). Processing of session closure must be ordered/synchronized
+     * with message delivery, such that if this session was open, any messages previously passed to
+     * sendMessageToEndpoint() that are still in-flight must still be delivered before the session
+     * is closed. Any in-flight messages to the endpoint that requested to close the session will
+     * not be delivered.
+     *
+     * @param sessionId The integer representing the communication session, previously set in
+     *         openEndpointSession() or onEndpointSessionOpenRequest().
+     * @param reason The reason for this close endpoint session request.
+     *
+     * @throws EX_ILLEGAL_ARGUMENT if any of the arguments are invalid, or the combination of the
+     *         arguments is invalid.
+     * @throws EX_SERVICE_SPECIFIC on other errors
+     *         - EX_CONTEXT_HUB_UNSPECIFIED if the request failed for other reasons.
+     */
+    void closeEndpointSession(int sessionId, in Reason reason);
+
+    /**
+     * Notifies the HAL that the session requested by onEndpointSessionOpenRequest is ready to use.
+     *
+     * @param sessionId The integer representing the communication session, previously set in
+     *         onEndpointSessionOpenRequest(). This id is assigned by the HAL.
+     *
+     * @throws EX_ILLEGAL_ARGUMENT if any of the arguments are invalid, or the combination of the
+     *         arguments is invalid.
+     * @throws EX_SERVICE_SPECIFIC on other errors
+     *         - EX_CONTEXT_HUB_UNSPECIFIED if the request failed for other reasons.
+     */
+    void endpointSessionOpenComplete(int sessionId);
 }
diff --git a/contexthub/aidl/android/hardware/contexthub/IEndpointCallback.aidl b/contexthub/aidl/android/hardware/contexthub/IEndpointCallback.aidl
new file mode 100644
index 0000000..972853b
--- /dev/null
+++ b/contexthub/aidl/android/hardware/contexthub/IEndpointCallback.aidl
@@ -0,0 +1,118 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * 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
+ *
+ *      http://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.
+ */
+
+package android.hardware.contexthub;
+
+import android.hardware.contexthub.EndpointId;
+import android.hardware.contexthub.EndpointInfo;
+import android.hardware.contexthub.Message;
+import android.hardware.contexthub.MessageDeliveryStatus;
+import android.hardware.contexthub.Reason;
+import android.hardware.contexthub.Service;
+
+@VintfStability
+interface IEndpointCallback {
+    /**
+     * Lifecycle event notification for endpoint starting from remote side. There is no need to
+     * report already started endpoint prior to the registration of an EndpointLifecycleCallbacks
+     * object. The EndpointInfo reported here should be consistent with values from getEndpoints().
+     *
+     * Endpoints added by registerEndpoint should not be included. registerEndpoint() should not
+     * cause this call.
+     *
+     * @param endpointInfos An array of EndpointInfo representing endpoints that just started.
+     */
+    void onEndpointStarted(in EndpointInfo[] endpointInfos);
+
+    /**
+     * Lifecycle event notification for endpoint stopping from remote side. There is no need to
+     * report already stopped endpoint prior to the registration of an EndpointLifecycleCallbacks
+     * object. The EndpointId reported here should represent a previously started Endpoint.
+     *
+     * When a hub crashes or restart, events should be batched into be a single call (containing all
+     * the EndpointId that were impacted).
+     *
+     * Endpoints added by registerEndpoint should not be included. unregisterEndpoint() should not
+     * cause this call.
+     *
+     * @param endpointIds An array of EndpointId representing endpoints that just stopped.
+     * @param reason The reason for why the endpoints stopped.
+     */
+    void onEndpointStopped(in EndpointId[] endpointIds, Reason reason);
+
+    /**
+     * Invoked when an endpoint sends message to another endpoint (on host) on the (currently open)
+     * session.
+     *
+     * @param sessionId The integer representing the communication session, previously set in
+     *         openEndpointSession() or onEndpointSessionOpenRequest().
+     * @param msg The Message object representing a message from endpoint to an endpoint on host.
+     */
+    void onMessageReceived(int sessionId, in Message msg);
+
+    /**
+     * Invoked when an endpoint sends the response for a message that requires delivery status.
+     *
+     * The response is the message delivery status of a recently sent message within a session. See
+     * sendMessageDeliveryStatusToEndpoint() for more details.
+     *
+     * @param sessionId The integer representing the communication session, previously set in
+     *         openEndpointSession() or onEndpointSessionOpenRequest().
+     * @param msgStatus The MessageDeliveryStatus object representing the delivery status for a
+     *         specific message (identified by the sequenceNumber) within the session.
+     */
+    void onMessageDeliveryStatusReceived(int sessionId, in MessageDeliveryStatus msgStatus);
+
+    /**
+     * Invoked when session initiation is requested by a remote endpoint. The receiving host client
+     * must later call endpointSessionOpenComplete() to indicate successful connection and
+     * acceptance of the session, or closeEndpointSession() to indicate failure.
+     *
+     * @param sessionId Caller-allocated session identifier, which must be unique across all active
+     *         sessions, and must not fall in a range allocated via requestSessionIdRange().
+     * @param destination The EndpointId representing the destination side of the session, which
+     *         must've already been published through registerEndpoint().
+     * @param initiator The EndpointId representing the initiating side of the session.
+     * @param serviceDescriptor Descriptor for the service specification for scoping this session
+     *         (nullable). Null indicates a fully custom marshalling scheme. The value should match
+     *         a published descriptor for both endpoints.
+     *
+     * @throws EX_ILLEGAL_ARGUMENT if any of the arguments are invalid, or the combination of the
+     *         arguments is invalid.
+     */
+    void onEndpointSessionOpenRequest(int sessionId, in EndpointId destination,
+            in EndpointId initiator, in @nullable String serviceDescriptor);
+
+    /**
+     * Invoked when a session has either failed to open, or has been closed by the remote side.
+     * Upon receiving this callback, the session is closed and further messages on it will not be
+     * delivered.
+     *
+     * @param sessionId The integer representing the communication session, previously set in
+     *         openEndpointSession() or onEndpointSessionOpenRequest().
+     * @param reason The reason for this close endpoint session notification.
+     */
+    void onCloseEndpointSession(int sessionId, in Reason reason);
+
+    /**
+     * Callback when a session is opened. This callback is the status callback for a previous
+     * openEndpointSession().
+     *
+     * @param sessionId The integer representing the communication session, previously set in
+     *         onEndpointSessionOpenRequest(). This id is assigned by the host.
+     */
+    void onEndpointSessionOpenComplete(int sessionId);
+}
diff --git a/contexthub/aidl/android/hardware/contexthub/Message.aidl b/contexthub/aidl/android/hardware/contexthub/Message.aidl
new file mode 100644
index 0000000..fc81ab0
--- /dev/null
+++ b/contexthub/aidl/android/hardware/contexthub/Message.aidl
@@ -0,0 +1,51 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * 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
+ *
+ *      http://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.
+ */
+
+package android.hardware.contexthub;
+
+@VintfStability
+parcelable Message {
+    /**
+     * Bitmask for flags field if this message requires a MessageDeliveryStatus for the
+     * sequenceNumber within 1 second.
+     */
+    const int FLAG_REQUIRES_DELIVERY_STATUS = 1;
+
+    /** Bitset of flags */
+    int flags;
+
+    /** Sequence number of this message */
+    int sequenceNumber;
+
+    /**
+     * Per message permission (used for app-op permission attribution).
+     */
+    String[] permissions;
+
+    /**
+     * The type of this message payload, following a scheme specific to the service or sending
+     * endpoint's communication protocol. This value can be used to distinguish the handling of
+     * content (e.g. for decoding). This could also be used as the complete content of the message
+     * if no additional payload is needed.
+     */
+    int type;
+
+    /**
+     * Content (payload) of the message. The format of the message is specific to the context of the
+     * message: the service or endpoints involved in the session, and the message type.
+     */
+    byte[] content;
+}
diff --git a/contexthub/aidl/android/hardware/contexthub/MessageDeliveryStatus.aidl b/contexthub/aidl/android/hardware/contexthub/MessageDeliveryStatus.aidl
index ae425b3..4129981 100644
--- a/contexthub/aidl/android/hardware/contexthub/MessageDeliveryStatus.aidl
+++ b/contexthub/aidl/android/hardware/contexthub/MessageDeliveryStatus.aidl
@@ -21,7 +21,8 @@
 @VintfStability
 parcelable MessageDeliveryStatus {
     /**
-     * The messageSequenceNumber of the ContextHubMessage to which this status applies.
+     * The messageSequenceNumber of the ContextHubMessage or Message to which this status is
+     * required.
      */
     int messageSequenceNumber;
 
diff --git a/contexthub/aidl/android/hardware/contexthub/Reason.aidl b/contexthub/aidl/android/hardware/contexthub/Reason.aidl
new file mode 100644
index 0000000..65d9f8a
--- /dev/null
+++ b/contexthub/aidl/android/hardware/contexthub/Reason.aidl
@@ -0,0 +1,66 @@
+/*
+ * Copyright (C) 2023 The Android Open Source Project
+ *
+ * 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
+ *
+ *      http://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.
+ */
+
+package android.hardware.contexthub;
+
+@VintfStability
+@Backing(type="byte")
+enum Reason {
+    /**
+     * Unspecified reason.
+     */
+    UNSPECIFIED = 0,
+
+    /**
+     * Out of memory. There's not enough memory to perform this operation.
+     */
+    OUT_OF_MEMORY,
+
+    /**
+     * Timeout. This operation timed out.
+     */
+    TIMEOUT,
+
+    /**
+     * Endpoint rejected this openEndpointSession request.
+     */
+    OPEN_ENDPOINT_SESSION_REQUEST_REJECTED,
+
+    /**
+     * Endpoint requested closeEndpointSession.
+     */
+    CLOSE_ENDPOINT_SESSION_REQUESTED,
+
+    /**
+     * Invalid endpoint.
+     */
+    ENDPOINT_INVALID,
+
+    /**
+     * Endpoint is now stopped.
+     */
+    ENDPOINT_GONE,
+
+    /**
+     * Endpoint crashed.
+     */
+    ENDPOINT_CRASHED,
+
+    /**
+     * Hub was reset or is resetting.
+     */
+    HUB_RESET,
+}
diff --git a/contexthub/aidl/android/hardware/contexthub/Service.aidl b/contexthub/aidl/android/hardware/contexthub/Service.aidl
new file mode 100644
index 0000000..fd748c3
--- /dev/null
+++ b/contexthub/aidl/android/hardware/contexthub/Service.aidl
@@ -0,0 +1,67 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * 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
+ *
+ *      http://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.
+ */
+
+package android.hardware.contexthub;
+
+@VintfStability
+parcelable Service {
+    /**
+     * Type of the Service. This field defines the messaging format used for this service.
+     * The format refers to how the data would be marhsalled in messages between host endpoint (on
+     * Android) and endpoint on the Context Hub or generic hub.
+     */
+    RpcFormat format;
+
+    /**
+     * Uniquely identifies the interface (scoped to type). Conventions depend on interface type.
+     * Examples:
+     *   1. AOSP-defined AIDL: android.hardware.something.IFoo/default
+     *   2. Vendor-defined AIDL: com.example.something.IBar/default
+     *   3. Pigweed RPC with Protobuf: com.example.proto.ExampleService
+     */
+    String serviceDescriptor;
+
+    /** Breaking changes should be a major version bump. */
+    int majorVersion;
+    /** Monotonically increasing minor version. */
+    int minorVersion;
+
+    /** Hook for additional detail in vendor-specific type */
+    ParcelableHolder extendedInfo;
+
+    /**
+     * Supported messaging format for the service between the host and the hubs.
+     */
+    @VintfStability
+    @Backing(type="int")
+    enum RpcFormat {
+        /**
+         * Customized format for messaging. Fully customized and opaque messaging format.
+         */
+        CUSTOM = 0,
+        /**
+         * Binder-based messaging. The host endpoint is defining this service in Stable AIDL.
+         * Messages between endpoints that uses this service will be using the binder marhsalling
+         * format.
+         */
+        AIDL = 1,
+        /**
+         * Pigweed RPC messaging with Protobuf. This endpoint is a Pigweed RPC. Messages between
+         * endpoints will use Pigweed RPC marshalling format (protobuf).
+         */
+        PW_RPC_PROTOBUF = 2,
+    }
+}
diff --git a/contexthub/aidl/android/hardware/contexthub/VendorHubInfo.aidl b/contexthub/aidl/android/hardware/contexthub/VendorHubInfo.aidl
new file mode 100644
index 0000000..524c7e8
--- /dev/null
+++ b/contexthub/aidl/android/hardware/contexthub/VendorHubInfo.aidl
@@ -0,0 +1,33 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * 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
+ *
+ *      http://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.
+ */
+
+package android.hardware.contexthub;
+
+/**
+ * A representation of a vendor-specific hub providing endpoints (with services). The hub does not
+ * run the Context Hub Runtime Environment, but exposes a similar messaging API.
+ */
+@VintfStability
+parcelable VendorHubInfo {
+    /** Descriptive name of the basic hub */
+    String name;
+
+    /** Version of the hub */
+    int version;
+
+    /** Hook for additional detail in vendor-specific type */
+    ParcelableHolder extendedInfo;
+}
diff --git a/contexthub/aidl/default/Android.bp b/contexthub/aidl/default/Android.bp
index 2960746..da173f9 100644
--- a/contexthub/aidl/default/Android.bp
+++ b/contexthub/aidl/default/Android.bp
@@ -30,7 +30,7 @@
     shared_libs: [
         "libbase",
         "libbinder_ndk",
-        "android.hardware.contexthub-V3-ndk",
+        "android.hardware.contexthub-V4-ndk",
     ],
     export_include_dirs: ["include"],
     srcs: [
@@ -51,7 +51,7 @@
     shared_libs: [
         "libbase",
         "libbinder_ndk",
-        "android.hardware.contexthub-V3-ndk",
+        "android.hardware.contexthub-V4-ndk",
     ],
     static_libs: [
         "libcontexthubexampleimpl",
diff --git a/contexthub/aidl/default/ContextHub.cpp b/contexthub/aidl/default/ContextHub.cpp
index bd483d7..5713a1b 100644
--- a/contexthub/aidl/default/ContextHub.cpp
+++ b/contexthub/aidl/default/ContextHub.cpp
@@ -136,4 +136,83 @@
     return ScopedAStatus::fromExceptionCode(EX_UNSUPPORTED_OPERATION);
 }
 
+ScopedAStatus ContextHub::getHubs(std::vector<HubInfo>* _aidl_return) {
+    ContextHubInfo hub = {};
+    hub.name = "Mock Context Hub";
+    hub.vendor = "AOSP";
+    hub.toolchain = "n/a";
+    hub.id = kMockHubId;
+    hub.peakMips = 1;
+    hub.maxSupportedMessageLengthBytes = 4096;
+    hub.chrePlatformId = UINT64_C(0x476f6f6754000000);
+    hub.chreApiMajorVersion = 1;
+    hub.chreApiMinorVersion = 6;
+    hub.supportsReliableMessages = false;
+
+    HubInfo hubInfo1 = {};
+    hubInfo1.hubId = hub.chrePlatformId;
+    hubInfo1.hubDetails = HubInfo::HubDetails::make<HubInfo::HubDetails::Tag::contextHubInfo>(hub);
+
+    VendorHubInfo vendorHub = {};
+    vendorHub.name = "Mock Vendor Hub";
+    vendorHub.version = 42;
+
+    HubInfo hubInfo2 = {};
+    hubInfo1.hubId = UINT64_C(0x1234567812345678);
+    hubInfo1.hubDetails =
+            HubInfo::HubDetails::make<HubInfo::HubDetails::Tag::vendorHubInfo>(vendorHub);
+
+    _aidl_return->push_back(hubInfo1);
+    _aidl_return->push_back(hubInfo2);
+
+    return ScopedAStatus::ok();
+};
+
+ScopedAStatus ContextHub::getEndpoints(std::vector<EndpointInfo>* /* _aidl_return */) {
+    return ScopedAStatus::fromExceptionCode(EX_UNSUPPORTED_OPERATION);
+};
+
+ScopedAStatus ContextHub::registerEndpoint(const EndpointInfo& /* in_endpoint */) {
+    return ScopedAStatus::fromExceptionCode(EX_UNSUPPORTED_OPERATION);
+};
+
+ScopedAStatus ContextHub::unregisterEndpoint(const EndpointInfo& /* in_endpoint */) {
+    return ScopedAStatus::fromExceptionCode(EX_UNSUPPORTED_OPERATION);
+};
+
+ScopedAStatus ContextHub::registerEndpointCallback(
+        const std::shared_ptr<IEndpointCallback>& /* in_callback */) {
+    return ScopedAStatus::fromExceptionCode(EX_UNSUPPORTED_OPERATION);
+};
+
+ScopedAStatus ContextHub::requestSessionIdRange(int32_t /* in_size */,
+                                                std::vector<int32_t>* /* _aidl_return */) {
+    return ScopedAStatus::fromExceptionCode(EX_UNSUPPORTED_OPERATION);
+};
+
+ScopedAStatus ContextHub::openEndpointSession(
+        int32_t /* in_sessionId */, const EndpointId& /* in_destination */,
+        const EndpointId& /* in_initiator */,
+        const std::optional<std::string>& /* in_serviceDescriptor */) {
+    return ScopedAStatus::fromExceptionCode(EX_UNSUPPORTED_OPERATION);
+};
+
+ScopedAStatus ContextHub::sendMessageToEndpoint(int32_t /* in_sessionId */,
+                                                const Message& /* in_msg */) {
+    return ScopedAStatus::fromExceptionCode(EX_UNSUPPORTED_OPERATION);
+};
+
+ScopedAStatus ContextHub::sendMessageDeliveryStatusToEndpoint(
+        int32_t /* in_sessionId */, const MessageDeliveryStatus& /* in_msgStatus */) {
+    return ScopedAStatus::fromExceptionCode(EX_UNSUPPORTED_OPERATION);
+};
+
+ScopedAStatus ContextHub::closeEndpointSession(int32_t /* in_sessionId */, Reason /* in_reason */) {
+    return ScopedAStatus::fromExceptionCode(EX_UNSUPPORTED_OPERATION);
+};
+
+ScopedAStatus ContextHub::endpointSessionOpenComplete(int32_t /* in_sessionId */) {
+    return ScopedAStatus::fromExceptionCode(EX_UNSUPPORTED_OPERATION);
+};
+
 }  // namespace aidl::android::hardware::contexthub
diff --git a/contexthub/aidl/default/contexthub-default.xml b/contexthub/aidl/default/contexthub-default.xml
index 2f8ddc8..359bb0a 100644
--- a/contexthub/aidl/default/contexthub-default.xml
+++ b/contexthub/aidl/default/contexthub-default.xml
@@ -1,7 +1,7 @@
 <manifest version="1.0" type="device">
     <hal format="aidl">
         <name>android.hardware.contexthub</name>
-        <version>3</version>
+        <version>4</version>
         <interface>
             <name>IContextHub</name>
             <instance>default</instance>
diff --git a/contexthub/aidl/default/include/contexthub-impl/ContextHub.h b/contexthub/aidl/default/include/contexthub-impl/ContextHub.h
index 72e8b3b..5680a77 100644
--- a/contexthub/aidl/default/include/contexthub-impl/ContextHub.h
+++ b/contexthub/aidl/default/include/contexthub-impl/ContextHub.h
@@ -53,6 +53,24 @@
             int32_t in_contextHubId,
             const MessageDeliveryStatus& in_messageDeliveryStatus) override;
 
+    ::ndk::ScopedAStatus getHubs(std::vector<HubInfo>* _aidl_return) override;
+    ::ndk::ScopedAStatus getEndpoints(std::vector<EndpointInfo>* _aidl_return) override;
+    ::ndk::ScopedAStatus registerEndpoint(const EndpointInfo& in_endpoint) override;
+    ::ndk::ScopedAStatus unregisterEndpoint(const EndpointInfo& in_endpoint) override;
+    ::ndk::ScopedAStatus registerEndpointCallback(
+            const std::shared_ptr<IEndpointCallback>& in_callback) override;
+    ::ndk::ScopedAStatus requestSessionIdRange(int32_t in_size,
+                                               std::vector<int32_t>* _aidl_return) override;
+    ::ndk::ScopedAStatus openEndpointSession(
+            int32_t in_sessionId, const EndpointId& in_destination, const EndpointId& in_initiator,
+            const std::optional<std::string>& in_serviceDescriptor) override;
+    ::ndk::ScopedAStatus sendMessageToEndpoint(int32_t in_sessionId,
+                                               const Message& in_msg) override;
+    ::ndk::ScopedAStatus sendMessageDeliveryStatusToEndpoint(
+            int32_t in_sessionId, const MessageDeliveryStatus& in_msgStatus) override;
+    ::ndk::ScopedAStatus closeEndpointSession(int32_t in_sessionId, Reason in_reason) override;
+    ::ndk::ScopedAStatus endpointSessionOpenComplete(int32_t in_sessionId) override;
+
   private:
     static constexpr uint32_t kMockHubId = 0;
     std::shared_ptr<IContextHubCallback> mCallback;