WebSockets is a stream, not a message based protocol

Re:WebSockets is a stream, not a message based protocol by samwillis on Wednesday December 21, 2011 @11:15AM (#3377955)

It seems to me that the hype around Web Sockets has overshadowed the Server Sent Events API (http://dev.w3.org/html5/eventsource/) which for most situations where you don't need a continues stream of data is a more sensible system. It is purely a message sending system by design.

The really nice thing about SSE is that you can fall back to long polling very easily with exactly the same back end and as it runs over vanilla http without the upgrade protocol system is much easer to implement, you just don't close the connection after sending a message. Obviously its only one way but we have a well established way of sending messages in the other direction with http POST.

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Re:WebSockets is a stream, not a message based protocol by LeafStorm on Wednesday December 21, 2011 @12:14PM (#3378211)

Of course, the limitation of SSE is that it's not bidirectional - as the name implies, only the server can send messages to the client. SSE is definitely useful, especially when you don't need the full overhead of a WebSockets server, but the "hype around WebSockets" is largely because you can implement two-way connections with it. Yesterday there was actually a HN post where someone created a full TCP proxy using WebSockets.

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Re:WebSockets is a stream, not a message based protocol by samwillis on Wednesday December 21, 2011 @12:26PM (#3378268)

I completely agree that WebSockets are a very good innovation and have their place but I do think that there are a lot of situations where you can achieve the same result easer with SSE and using a HTTP PUT to send messages back to the server.

For example a collaborative project management tool like Asana where saves are silent and update live on other peoples screens is a better place for SSE and a REST api than WebSockets, where as a real time game is probably a good place to the latter.

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Re:WebSockets is a stream, not a message based protocol by franksalim on Wednesday December 21, 2011 @01:03PM (#3378415)

The TCP proxy use case, which has been my primary motivation for WebSocket since day one, points to another limitation of SSE. SSE cannot handle binary data without encoding the data into text. WebSocket can.

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Re:WebSockets is a stream, not a message based protocol by bobfunk on Wednesday December 21, 2011 @03:06PM (#3378908)

Agree, Server Sent Events is an incredibly simple API, has none of the problems with proxies, security and complexity that websockets has run into and is perfect for the typical case where Ajax is fine for sending events to the server, but you need a way to stream events in the other direction.

I just launched the beta of a small service for making Server Sent Events painless at http://eventsourcehq.com

It's currently only available for members of Heroku's beta program, but I plan on launching it as a stand alone service as well. In any case all the code behind it available on Github...

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Re:WebSockets is a stream, not a message based protocol by scarmig on Wednesday December 21, 2011 @11:49AM (#3378097)

Which browsers have implemented SSE/EventSource?

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Re:WebSockets is a stream, not a message based protocol by pornel on Wednesday December 21, 2011 @11:59AM (#3378140)

All except IE and Android, as usual.

http://www.caniuse.com/#search=eventsource

However, since SSE is HTTP-compatible you can easily implement fallback for these, e.g.

https://github.com/Yaffle/EventSource

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Re:WebSockets is a stream, not a message based protocol by scarmig on Wednesday December 21, 2011 @12:24PM (#3378260)

Wow, I seem to have missed the boat on caniuse.com =)

Thanks for the info, everyone.

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Re:WebSockets is a stream, not a message based protocol by samwillis on Wednesday December 21, 2011 @12:04PM (#3378171)

http://caniuse.com/#search=eventsource

Firefox, Chrome, Safari and Opera all have it. I believe IE10 will have it but I cant find a reference right now.

This seems to be the nicest shim to let you use EventSource on older browsers https://github.com/Yaffle/EventSource, I did make something similar myself but this is much more complete.

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Re:WebSockets is a stream, not a message based protocol by laughinghan on Wednesday December 21, 2011 @12:07PM (#3378182)

Chrome 13+, Firefox 6+, Safari 5+, Opera 11+. No IE support on the horizon, though.

http://caniuse.com/#feat=eventsource

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