code: func NewSyncProtocolServerMiddleware(bizDecoder Decoder, bizEncoder Encoder, writer func(IOSession, interface{}) error) Middleware {
  	return &syncServerMiddleware{
  		bizDecoder:     bizDecoder,
  		bizEncoder:     bizEncoder,
  		writer:         writer,
  		offsetQueueMap: make(map[interface{}]*OffsetQueue),
  	}
  }
docs: // NewSyncProtocolServerMiddleware return a middleware to process sync protocol