Comments on: Native Comet Support for Browsers

By: musicfreak

musicfreak — Tue, 11 Mar 2008 06:06:42 +0000

I also agree that sockets are much better than Comet. It’ll have to due, I guess, but I’d much rather have true bidirectional communication than a work-around. The problem is there are too many issues in implementing it (firewalls, browser support *coughIEcough*, etc).

By: kriszyp

kriszyp — Sat, 19 Jan 2008 01:22:38 +0000

Sockets is good for certain applications with controlled clients, but with firewalls and proxy servers, it is not really a practical solution for general Comet use, as Thomas pointed out. Client sockets often get through proxy firewalls, and server sockets get you no where. Direct TCP/IP/Sockets doesn’t really provide that much HTTP, if you have full bi-directional streaming in HTTP (which is supported by the protocol). Sockets don’t get you much, it is bi-directional streaming that is needed and HTTP is right place for it.
Thomas, I am not sure what you mean by Comet being “connectionless”. Most Comet apps have a very strong concept of a connection (within which they send subscriptions and receive relevant events).

By: Thomas Powell

Thomas Powell — Fri, 18 Jan 2008 23:40:09 +0000

Sockets is the way to go. In doing the research for my upcoming Ajax book it was clear that trying to jam a two direction persistent connections into a connectionless protocol – yes that is what you are doing – is simply a hack even in the best cases. Interestingly it is clear that the implementation of the first native Comet like stuff as Opera does is really just the same stuff we have lurking under an API. Though we should all note that as soon as we do get what we want (sockets) the firewall impact will be large both on client and server-side. It seems port80 + HTTP is allowed so we just drive everything through it for better or worse.

By: Andy Kant

Andy Kant — Fri, 18 Jan 2008 21:08:57 +0000

Agreed with pkenoyer, if anythings gonna get implemented, native javascript sockets would be better. But it might be more likely for something like this to be implemented until sockets get standardized because it will be easier to handle fallback for older clients.

By: dkubb

dkubb — Fri, 18 Jan 2008 18:10:35 +0000

@ pkenoyer: I gotta agree with your idea of implementing Javascript Sockets. That would make things so much more flexible than just extending XHR. Libraries could be built on top of low level sockets to abstract away all of the details, and we could experiment with several different Comet approaches until a clear winner emerges. Its only when a common pattern emerges that we should begin thinking about formalizing the approach.

By: pkenoyer

pkenoyer — Fri, 18 Jan 2008 17:12:54 +0000

Why Comet? Why not JavaScript Sockets? You know, sockets, like what “real” applications use… True bidirectional communications.

I’m using Sockets all the time for my web applications using Flash. It works great.

By: Robin

Robin — Fri, 18 Jan 2008 15:45:03 +0000

W3’s XMLHttpRequest standardisation process is still in working draft. Best way to get it added would be to send a proposal to the public-webapi@w3.org mailing list, then to defend it.