Let's remove the extra info inside stream message

[windmemory]

After significant amount of investigation on [how to send FileBox name with stream message], I finally figured out the solution, which does not require any extra info in the request or response messages.

Example

Server

messageFileStream: async (call) => {
  // Get some arguments from the request
  const id = call.request.getId()
  // Get the stream from FileBox
  const fileBox = FileBox.fromFile(`${__dirname}/test.json`)
  const stream = await fileBox.toStream()
  // Create a shared response to use in stream
  const response = new MessageFileStreamResponse()
  response.setName(fileBox.name)
  // Create a metadata to store the extra info and send it to client
  const metaData = new grpc.Metadata()
  metaData.add('fileName', fileBox.name)
  call.sendMetadata(metaData)

  stream.on('data', (data: Buffer) => {
    response.setData(data)
    call.write(response)
  }).on('end', () => {
    call.end()
  })
},

Client

public async makeCallStream (i: number) {
  // construct a request with parameters
  const request = new MessageFileStreamRequest()
  request.setId(i.toString())
  // make the call to the server and get the stream response
  const stream = this.grpcClient.messageFileStream(request)
  // read the metadata and get the extra info from it
  const fileName = await new Promise<string>((resolve, reject) => {
    stream.once('metadata', (metaData: grpc.Metadata) => {
      const nameValues = metaData.get(FILE_BOX_NAME_METADATA_KEY)
      resolve(nameValues[0].toString())
    })
  })

  const outputStream = new PassThrough()
  // read data from the stream
  stream.on('data', (response: MessageFileStreamResponse) => {
    oStream.write(response.getData())
  }).on('end', () => {
    oStream.end()
  })

  const fileBox = FileBox.fromStream(outputStream, fileName)
  return fileBox
}

So with this design, we don't need extra attributes that we added onto MessageImageStreamResponse, MessageFileStreamResponse and MessageSendFileStreamRequest , to make the proto clear, let's remove these attributes.

[windmemory]

I just realized that when we want to send FileBox via grpc, the message should always be the same, so let's use a common message definition for the message that is actually a FileBox.

[huan]

Thanks for make the code clean!

To make our design more clean, I'd like to say that what we are sending and receiving is a standard nodejs ReadableStream.

So I'm thinking about to rename the file box related named to just steam related, for example, data chunks.

[huan]

Close this issue because this problem has been solved.

Thanks for creating this issue to explain the potential solution, it's very valuable!