Synchronous HTTP call in Netty

Question

My app receives an HTTP request, and in the middle of the pipeline, a call is made to another server for supporting information. The initial HTTP request can't continue through the pipeline until that response comes back. I can't use the awaitUninterruptability() from an I/O thread, so what's the best approach to make these calls so I don't block Netty's event loop, but put the client's pipeline on hold until my call out returns and I tell the pipeline to continue on?

Answer 1

Ryan this does not sound like a good idea..

I think you should better use something like that:

public class HttpHandler extends SimpleChannelUpstreamHandler{

    @Override
    public void messageReceived(final ChannelHandlerContext ctx, final MessageEvent e) throws Exception {
        otherChannel.write(yourRequet).addListener(new ChannelFutureListener() {

            public void operationComplete(ChannelFuture future) throws Exception {

                // once the write is done we can continue in the pipeline
                ctx.sendUpstream(e);
            }
        });

        // the event stops here to get processed

    }

}

If you need to wait for the response then you will need to handle it in another SimpleChannelUpstreamHandler. But I think you get the idea..

Answer 2

I guess you need an ExecutionHandler.