SSE now works with preceding channel handlers such as SSL

[johanhaleby]

Previously it was not possible to connect to a SSE server that also used SSL (https). The reason is that SSEInboundHandler / SseChannelHandler added the ServerSentEventDecoder before the SSL decoder handler in the pipeline chain which made ServerSentEventDecoder operate on encrypted data. This pull requests corrects this by not adding the ServerSentEventDecoder first in the pipeline.

[NiteshKant]

@johanhaleby thanks for the PR!

Looking at the code now, it seems that the if (!HttpHeaders.isTransferEncodingChunked((HttpResponse) msg)) check is unnecessary and we can unconditionally add the decoder after the SseChannelHandler. However, I do not have a way to reproduce the issue you are facing. Do you mind pointing me to a sample which does not work with the current release?

[johanhaleby]

I discovered this when I was working with https support in Turbine (here's the link to that pull request). After a lot of investigation and trail-and-error I found that this was the problem. Unfortunately I couldn't write an automated test case to verify it. I discovered it while trying to combine SSE and SSL in Turbine. The changes made here and in Turbine made it work for our Hystrix stream that is using https.

[NiteshKant]

ok @johanhaleby can you verify if turbine streams work over SSL when instead of the code in this PR:

if (!HttpHeaders.isTransferEncodingChunked((HttpResponse) msg)) {
                pipeline.addBefore(NAME, SSE_DECODER_HANDLER_NAME, new ServerSentEventDecoder());
                /*
                 * If there are buffered messages in the previous handler at the time this message is read, we would
                 * not be able to convert the content into an SseEvent. For this reason, we also add the decoder after
                 * this handler, so that we can handle the buffered messages.
                 * See the class level javadoc for more details.
                 */
                pipeline.addAfter(NAME, SSE_DECODER_POST_INBOUND_HANDLER, new ServerSentEventDecoder());
            } else {
                pipeline.addAfter(NAME, SSE_DECODER_HANDLER_NAME, new ServerSentEventDecoder());
            }

you change it to:

               pipeline.addAfter(NAME, SSE_DECODER_HANDLER_NAME, new ServerSentEventDecoder());

i.e. remove the check if(!HttpHeaders.isTransferEncodingChunked((HttpResponse) msg)) and unconditionally add the ServerSentEventDecoder to the pipeline after SseChannelHandler.

I did verify that SSE over plain HTTP works with this change. If this does work then I would like to instead make this change and remove the redundant check.

[johanhaleby]

@NiteshKant It seems to work without the if-statement. FYI this is our Nginx settings in production on the server I'm testing against:

proxy_buffering off;
proxy_cache off;
proxy_set_header Connection '';
chunked_transfer_encoding off;

I.e. transfer encoding is indeed off.

[johanhaleby]

I've updated the pull request and removed the if-statement

[NiteshKant]

Thanks @johanhaleby !