able to read chan and write chan

other/java/client/src/main/proto/filer.proto

@@ -50,6 +50,10 @@ service SeaweedFiler {
 
     rpc KeepConnected (stream KeepConnectedRequest) returns (stream KeepConnectedResponse) {
     }
+
+    rpc LocateBroker (LocateBrokerRequest) returns (LocateBrokerResponse) {
+    }
+
 }
 
 //////////////////////////////////////////////////
@@ -267,6 +271,21 @@ message LogEntry {
 message KeepConnectedRequest {
     string name = 1;
     uint32 grpc_port = 2;
+    repeated string resources = 3;
 }
 message KeepConnectedResponse {
 }
+
+message LocateBrokerRequest {
+    string resource = 1;
+}
+message LocateBrokerResponse {
+    bool found = 1;
+    // if found, send the exact address
+    // if not found, send the full list of existing brokers
+    message Resource {
+        string grpc_addresses = 1;
+        int32 resource_count = 2;
+    }
+    repeated Resource resources = 2;
+}