add rpc: LookupResource (#29)

Author: Time-Hu

hstream.proto

@@ -57,6 +57,7 @@ service HStreamApi {
   // Cluster APIs
   rpc DescribeCluster(google.protobuf.Empty) returns (DescribeClusterResponse) {
   }
+  rpc LookupResource(LookupResourceRequest) returns (ServerNode) {}
 
   // Admin Command
   rpc SendAdminCommand(AdminCommandRequest) returns (AdminCommandResponse);
@@ -483,3 +484,18 @@ message LookupShardReaderResponse {
   string readerId = 1;
   ServerNode serverNode = 2;
 }
+
+enum ResourceType {
+  ResStream = 0;
+  ResSubscription = 1;
+  ResShard = 2;
+  ResShardReader = 3;
+  ResConnector = 4;
+  ResQuery = 5;
+  ResView = 6;
+}
+
+message LookupResourceRequest {
+  ResourceType resType = 1;
+  string resId = 2;
+}