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  1. Hadoop Common
  2. HADOOP-8990

Clean up RPC protocol for consistency



    • Improvement
    • Status: Open
    • Major
    • Resolution: Unresolved
    • None
    • None
    • None
    • None
    • Incompatible change


      There are a few inconsistencies in the current RPC protocol that make new client implementation (especially non-blocking) unnecessarily hard. For example:

      1. proto file naming
        RpcPayloadHeader.proto include not only RpcPayLoadHeaderProto, but also RpcResponseHeaderProto, which is irrelevant to the file name.
        hadoop_rpc.proto only include HadoopRpcRequestProto, and the filename "hadoop_rpc" is strange comparing to other .proto file names.
        How about merge those two file into HadoopRpc.proto?
      2. proto class naming
        In rpc request RpcPayloadHeaderProto includes callId, but in rpc response callId is included in RpcResponseHeaderProto, and there is also HadoopRpcRequestProto, this is just too confusing.
      3. The rpc system is not fully protobuf based, there are still some Writables:
        RpcRequestWritable, RpcResponseWritable, rpc response exception name, stack trace string and sasl request/response.
        RpcRequestWritable uses protobuf style varint32 prefix, but RpcResponseWritable uses int32 prefix, why this inconsistency?

      Currently rpc request is splitted into length, PayLoadHeader and PayLoad, and response into RpcResponseHeader, response and error message. Wrapping request and response into single RequestProto and ResponseProto would be better, since this gives a formal complete wire format definition.

      These issues above make it very confusing and hard for developers to use these rpc interfaces.




            sanjay.radia Sanjay Radia
            decster Binglin Chang
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