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0 pointsmegaman82111y ago0 comments

All true but TCP has head-of-line blocking, which means even if resources are requested in parallel then can only be returned in the order they where requested.

In an ideal world we could switch to using something like the SCTP networking protocol with HTTP that would solve a lot of issues. Unfortunately we are stuck with TCP, so the application protocol (HTTP) now must implement a networking protocol so we can multiplex over a single connection.

At least people won't have to inline resources, sprite images, or concatenate CSS and JavaScript anymore. And header compression is a small upgrade to the spec.

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monstermonster11y ago

Couple of follow ups on this one:

SCTP is message oriented rather than stream oriented so this isn't really useful. The chunk size is also two bytes meaning that all your messages have to be less than 64k or you have to implement packet reassembly and stuff. Oh look, back at TCP again.

We must do nothing.

I suspect this entire SPDY/HTTP/2 reengineering effort is a 1000% complexity and risk increase for a 2-5% gain in performance. That is not a trade-off as an engineer I could accept.

90% of the inefficiency of web applications is down to the application stack, not the protocols. Sending hundreds of KiB of uncompressed text down rather than compressed abstract or native virtual machine instructions for example is a bigger win.

stormbrew11y ago

Boy, it was dumb of them to put stream in the name (Stream Control Transmission Protocol) if it wasn't capable of acting in a streaming manner.

Oh wait, SCTP can act in an ordered-with-congestion-control mode (aka stream-oriented), and the userland interface to it (the most basic form of which is just plain old Berkeley sockets) does in fact implement packet assembly (of course, no matter what, if you want packets bigger than the MTU something's gonna have to disassemble and reassemble them on some level of the stack anyways).

Not to say that SCTP is a practical solution given the glacial pace of acceptance of any new network protocol at its level, but let's not start spreading FUD about its capabilities.

bigbango11y ago

Yes, network protocols like IPv6 have a glacial deployment speed. Because all the network equipment have to support it.

But it isn't so for transport protocols like SCTP. Only the endpoints using it need to support it. So a transport protocol that provides a real benefit could be deployed relatively quickly.

megaman821OP11y ago

I am not trying to extol any virtues or negatives of SCTP, just comment that for HTTP/2 to have multiplexing over a single connect without the head-of-line block problem they have to implement messages also. Seems wasteful.

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