diff --git a/pandora/sdp.proto b/pandora/sdp.proto
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+// Copyright 2023 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.
+
+syntax = "proto3";
+
+option java_outer_classname = "SDPProto";
+
+package pandora.sdp;
+
+import "google/protobuf/empty.proto";
+import "google/protobuf/any.proto";
+import "pandora/host.proto";
+
+service SDP {
+  // Server methods
+  // Register an SDP service
+  rpc AddService(AddServiceRequest) returns (google.protobuf.Empty);
+  // Remove an SDP service
+  rpc RemoveService(RemoveServiceRequest) returns (google.protobuf.Empty);
+  // List all registered SDP services
+  rpc ListAttributes(ListAttributesRequest) returns (ListAttributesResponse);
+  // Client methods
+  // Connect an SDP protocol channel
+  rpc Connect(ConnectionRequest) returns (ConnectionResponse);
+  // Disconnect an SDP protocol channel
+  rpc Disconnect(DisconnectionRequest) returns (google.protobuf.Empty);
+  // Core Specification v5.2 Vol. 3 Part B Section 4.5
+  rpc ServiceSearch(ServiceSearchRequest) returns (ServiceSearchResponse);
+  // Core Specification v5.2 Vol. 3 Part B Section 4.6
+  rpc ServiceAttribute(ServiceAttributeRequest)
+      returns (ServiceAttributeResponse);
+  // Core Specification v5.2 Vol. 3 Part B Section 4.7
+  rpc ServiceSearchAttribute(ServiceSearchAttributeRequest)
+      returns (ServiceSearchAttributeResponse);
+}
+
+message Channel {
+  google.protobuf.Any cookie = 1;
+}
+
+message DataElementSequence {
+  repeated DataElement elements = 1;
+}
+
+message DataElement {
+  uint32 size = 1;
+  oneof type {
+    google.protobuf.Empty nil = 2;
+    uint32 unsigned_integer = 3;
+    int32 signed_integer = 4;
+    string uuid = 5;
+    string text_string = 6;
+    bool boolean = 7;
+    DataElementSequence sequence = 8;
+    DataElementSequence alternative = 9;
+  }
+}
+
+message ServiceAttribute {
+  uint32 id = 1;
+  DataElement value = 2;
+}
+
+message ConnectionRequest {
+  Connection connection = 1;
+}
+
+message ConnectionResponse {
+  oneof result {
+    Channel channel = 1;
+    google.protobuf.Empty connection_failed = 2;
+  }
+}
+
+message DisconnectionRequest {
+  Channel channel = 1;
+}
+
+message AddServiceRequest {
+  uint32 service_record_handle = 1;
+  repeated ServiceAttribute attributes_in_service = 2;
+}
+
+message RemoveServiceRequest {
+  uint32 service_record_handle = 1;
+}
+
+message ListAttributesRequest {}
+
+message ListAttributesResponse {
+  repeated ServiceAttribute attributes = 1;
+}
+
+message ServiceSearchRequest {
+  Channel channel = 1;
+  // A list of UUID to search for
+  repeated string service_search_pattern = 2;
+}
+
+message ServiceSearchResponse {
+  repeated uint32 service_record_handles = 1;
+}
+
+message ServiceAttributeRequest {
+  Channel channel = 1;
+  uint32 service_record_handle = 2;
+  // Must set either attribute_ids or attribute_id_ranges
+  // Each element represents an attribute ID (Only 16-bit meaningful)
+  repeated uint32 attribute_ids = 3;
+  // Must have even size.
+  // Each pair represents (range_begin(16-bit), range_end(16-bit))
+  repeated uint32 attribute_id_ranges = 4;
+}
+
+message ServiceAttributeResponse {
+  repeated ServiceAttribute attributes = 1;
+}
+
+message ServiceSearchAttributeRequest {
+  Channel channel = 1;
+  uint32 service_record_handle = 2;
+  // A list of UUID to search for
+  repeated string service_search_pattern = 3;
+  // Must set either
+  // Each element represents an attribute ID (16-bit meaningful)
+  repeated uint32 attribute_ids = 4;
+  // Each item represents (range_begin(16-bit), range_end(16-bit))
+  // (32-bit meaningful)
+  repeated uint32 attribute_id_ranges = 5;
+}
+
+message ServiceSearchAttributeResponse {
+  repeated ServiceAttribute attributes = 1;
+}