Upgrade multi-lang implementation which may have broken in Storm 0.9.3

[amontalenti]

Storm 0.9.3 release notes indicate that "the multi-lang API has changed in a non-backward-compatible way". This has something to do with the way that ShellBolts implement heartbeat'ing / sync'ing. Should test, investigate, and upgrade as necessary the ipc module.

[dan-blanchard]

And yet they still haven't updated the documentation for it. I find that the most frustrating part of working with Storm: the official documentation is very poorly formatted, and is frequently out of date.

[amontalenti]

@dan-blanchard blame me, I recently voluntwered to update the Storm docs. Wanna help? :)

[dan-blanchard]

I believe this diff shows the clearest indication of what actually changed.

The only changes to the protocol I see are:

• New metrics command. It looks like you can use it to report custom performance metrics in multilang bolts. The JIRA issue discussing it in more detail is here, and I didn't have a chance to read through all of it yet.
• Heartbeats (as mentioned in Add support for multilang heartbeats #70). To check if a received message is a heartbeat, we need to check that the task is -1 and the stream is __heartbeat. If we receive a heartbeat on the Python side, we need to send a sync back. Tuple heartbeats are not supposed to be processed (or acked) otherwise.

It also seems like it is recommended now that we use the error command instead of log to report exceptions, but we already did that in #75.

[dan-blanchard]

Consider listing the actual changes to the API above my contribution to that effort. ;)

Oh, and I should mentioned in my previous comment that heartbeats appear to only be sent to multilang bolts and not spouts.

[HeartSaVioR]

I've requested for pull to update documentation.
https://github.com/HeartSaVioR/storm/blob/STORM-544/docs/documentation/Multilang-protocol.md
But @dan-blanchard commented it already. ;)

[amontalenti]

patch from pyleus recently contributed:

https://github.com/Yelp/pyleus/pull/76/files

[dan-blanchard]

I should note that #87 made it so we're compatible with 0.9.3, but we're still not taking advantage of the ability to have custom metrics reported to Nimbus like was added in apache/storm#38. That should probably be a separate issue though.