// 2) the Payload - the RpcRequest
//
d = new DataOutputBuffer();
RpcPayloadHeaderProto header = ProtoUtil.makeRpcPayloadHeader(
call.rpcKind, RpcPayloadOperationProto.RPC_FINAL_PAYLOAD, call.id);
header.writeDelimitedTo(d);
call.rpcRequest.write(d);
byte[] data = d.getData();
int totalLength = d.getLength();
out.writeInt(totalLength); // Total Length