[MostAwesomeDude]

Anything that Comet or other long-polling techniques provide, really.

The advantages of WebSockets include constantly changing specifications which are neither backwards- nor forwards-compatible, a lack of proxy traversal, an arbitrary and unreasonable limitation on binary data transfer, and lack of unified browser and server support.

[dochtman]

It's not that bad. Right now you basically have support for the -76 protocol in release channel Chrome and Firefox 4 or 5, it's nearly trivial to support all of those with a single server.

With Firefox 6.0, I had to spend some time to upgrade our little Python server, but now it happily serves both -76 and -07. It also looks like -07 is very close to being signed off on as the actual standard, so the compatibility problems are probably a thing of the past soon (-76 and -07 are actually completely trivial to discern from a server point of view).

I haven't tried with binary data, but it looks like it's explicitly supported with -07. Not sure about proxies, they aren't relevant to our work app.

[yesimahuman]

For server side development, I've found that Jetty has a good websockets API. I had difficulty getting the server and browser to agree a few months ago when I tried it (common libs in python and C# were tested). Moving to Jetty got it working. I'm not sure how current it is though.

[daeken]

I've held off on using WebSockets until binary frames are supported. I'm amazed they haven't been so far.

[yesbabyyes]

Ericsson has a working implementation for this, they do voice and video browser to browser with Webkit:

https://labs.ericsson.com/apis/web-real-time-communication

http://news.ycombinator.com/item?id=2600585

[MostAwesomeDude]

In practice, things like Base64 encoding are used. That's what we use in Ganeti Web Manager to host a noVNC (HTML5 VNC client) and have it talk WebSockets with the backend.

In theory, there's no good reason we can't have binary frames; I have internally filed it under the "Why can't we have nice things?" category.

[intranation]

WebSockets will generally provide latency improvements over long-polling as they won't have the overhead of creating and breaking down many HTTP connections (as to "push" using long-polling you need to return to the browser). XHR-multipart communication is better than long-polling, but only Firefox supports it.