重用通道进行HTTP请求

Question

I want to reuse channel for multiple HTTP requests. I'm using java+netty for the server but clients could be written in C#/Java.

For the C# client I'm using HttpWebRequest with KeepAlive = true; and I don't close the channel after the arrival of the response. And it works perfect.

But when I tried the same for java <--> java communication I had some problems. I'm handling the responses from server something like in this sample and this client part.

If in if (msg instanceof LastHttpContent) { section I just do ctx.close(); I won't be able to reuse this channel again. What should I do here to be able to reuse it?

I tried:

ctx.write(new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.CONTINUE));

or

ctx.writeAndFlush(Unpooled.EMPTY_BUFFER);

or tried to do nothing...but when I try to reuse this channel, i have problem in this handle. The first request was handled fine, but the second gives me this error:

channelRead0: DefaultHttpResponse(decodeResult: failure(java.lang.NullPointerException), version: HTTP/1.1)

Section if (msg instanceof HttpResponse) works fine (I mean headers was read), but throws exception somewhere after that.

And:

headers().set(HttpHeaders.Names.CONNECTION, HttpHeaders.Values.KEEP_ALIVE);

doesn't help too. To make it clear: 1st request/response is fine. Second request in same stream is fine, but there is a problem in decoding the response.

I checked Logger. 1st and second responses are equal, so I don't understand why it gets NullException when decoding it.

ps netty 4.0.26

Answer 1

You are entirely at the mercy of the clients. If they implement connection pooling, your connection will be reused. If not, not. Nothing you can do about it at the server end except observe and implement the Connection: close header if sent.