HTTP vs. TCP (Re: "Binary XML" proposals)

[Stefan Zier <Stefan.Zier@syntion.com>]

> ...but if you're going to use TCP for RPCs, for God's sake don't use port
> 80; that's for transferring hypertext. We have 65,000 or so port numbers
> to choose from. If we use different port numbers for different things,
> firewall administrators can make networks secure by controlling what does
> and doesn't get let through. If Web browsing and RPCs all go over the same
> port, then it's hard to disallow or control RPCs without affecting web
> browsing.

It's a cat and mouse thing: more and more applications use port 80/HTTP
because firewall admins only allow web browsing. In return, firewall admins
move towards application level firewalls (aka proxies) instead of simple
packet filters. So in the end, both writing applications that are supposed
to go through firewalls and firewalls that disallow these applications
become more and more complex and, in general, a bit pain.

> We use HTTP for RPCs, anyway? Being able to reuse Apache isn't a great
> win. It's easy to listen on a port, perform some kind of authentication on
> incoming connections, then just choose a scheme for delimiting requests
> and an error-signalling system for use in response. Voila!

Well, it may well be simple to implement this, but don't you think it's
reinventing the weel all over again? There are very rugged HTTP
implementations available on really all important platforms and ready for
deployment today. Does anyone have numbers on how much bandwidth is wasted
in HTTP? Also, there's a lot of nice features, like SSL-encryption, that you
get for free when using HTTP.

---------------------------------------
Stefan Zier
Software Developer
Syntion AG - http://www.syntion.com
Leonrodplatz 2 - 80636 Munich/Germany
Phone +49 89 52 30 45-0
Fax +49 89 52 30 45-20