CODEWITHSUNDEEP
javac#httpasynchronousnetty
Tobias Timm
Tobias Timm

Reputation: 2050

C# client Java server HTTP no response

We have a java server application, who is listening on port 5545 for http communciation.

On the other side is a C# Client application, who sends requests to the server.

Before some problems with proxies occured, our communication was based on TCP/IP.

Now we wanna switch to a communication via http, but we experienced some strange behaviour on the c# side.

The problem is based on the PostAsync Method

Our Java Server is using the Netty 4 Framework with Spring. When the c# client post the data, i can see everything in the netty logs. Now at the part, where the java server sends the response back, the c# method is going into something like a deadlock.

My java method for sending the response is

private boolean writeResponse(boolean isSuccessful, String message, ChannelHandlerContext ctx) {
  boolean keepAlive = HttpHeaders.isKeepAlive(_httpRequest);
  FullHttpResponse response = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1,
    isSuccessful ? HttpResponseStatus.OK : HttpResponseStatus.BAD_REQUEST,
  Unpooled.copiedBuffer(message, CharsetUtil.UTF_8));
  response.headers().set(HttpHeaders.Names.ACCEPT_ENCODING, HttpHeaders.Values.GZIP);
  response.headers().set(HttpHeaders.Names.CONTENT_TYPE, "application/octet-stream; charset=UTF-8");
  if (keepAlive) {
    response.headers().set(HttpHeaders.Names.CONTENT_LENGTH, message.length());
    response.headers().set(HttpHeaders.Names.CONNECTION, HttpHeaders.Values.KEEP_ALIVE);
  }
  ctx.write(response);
  return keepAlive;
}

The c# client code is

HttpClientHandler httpClientHandler = new HttpClientHandler();
client = new System.Net.Http.HttpClient(httpClientHandler) { BaseAddress = uri };

byte[] bytes = ...
ByteArrayContent byteContent = new ByteArrayContent(bytes);
var response = await client.PostAsync(uri, byteContent, tokenSource.Token);

When i add ctx.channel().writeAndFlush(Unpooled.EMPTY_BUFFER).addListener(ChannelFutureListener.CLOSE); on the java side after the last write. The PostAsync Method gets a response, otherwise it is just stuck, although the java server send the response already.

So my question is, is this a normal behaviour or can someone explain me, what we are doing wrong?

Upvotes: 1

Views: 148

Answers (1)

ErWu
ErWu

Reputation: 465

You should set CONTENT_LENGTH everytime, not only when keepAlive is true.

[Edit] Otherwise the client does not know if and when response-content is fully received and the post-method will not return.

Upvotes: 1

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