Why is Web-based IM so slow?

[Angel Blue01]

In my networking class a few days ago the question came up: Why is it that it takes so long for a Web based instant messaenger (MSN Web Messenger, AIMExpress, etc) to send and recieve messages?

We had been talking about the difference between TCP and UDP.

My friend was wonderign if the fact that HTTP has to do a handshake, reliabity testing, congestion control, etc was slowing it down.

The teacher said it was due to a slow operating system, computer, etc. Obviously this not the case, when ordinary Web pages load fine, and local IM applications work in "real time" on a T1 line!

I thought it was (in AIM's case) that it has to convert the message to so many different protocols and across several different servers. The message has to go to the AIMExpress HTTP server on port 80, then to oscar.aol.com, sent through the Oscar protocol via port 3556 to the receiver's computer, etc.

I'm still wondering, and there does't seem to be any explanation on AIM or MSN's Web sites.

Does anyone know?

[ToneKnee]

Don't these online IM's use Stuff like Java to control the functions, data and whatnot? Java is slow, but it's Universal. If anything, it'll be down to the platform actually running these IM's.

Edit:

Another reason could be the fact MSN Messenger (this i can vouch for) directly connects to the user client, rather than the online ones which have to go through the HTTP servers, DNS servers and across the world to get to that person.

[XerXis]

first off all, they don't use http to send and receive the messages to the im network. The web im is just a ajax interface with sends the stuff you type to some backend program on their server (i made one in php once). The reason they are so slow is because they are not event based (at least only one way). they use a timer to control if you have received a new message etc. So there's a delay because of

a: the extra ajax layer

b: because you only receive your message after the ajax script has communicated with the server which only happens on a timely basis

[DangR]

I don't have any fancy "smancy" explanation, but you should check out:

http://www3.meebo.com

I haven't experienced that to be any slower then regular messenger..

[trigger_my_passion]

You can find more like meebo at http://del.icio.us/sridhar/im.

[Jase]

i use meebo to, and i never experience anything slow at all

[Angel Blue01]

I wasn't really looking for an alternative to the official Web based "apps" but thanks!

So its the JavaScript (browser-based part AJAX) and the time-based operation of the nature of the server backend that's slowing it down. What does meebo do that makes it faster?

XerXis, would you have a source for that explanation? I'd like to bring it up in class.

[L0rd_Aryan]

Just because, when u use a chat client say msm messenger, then u can connect directly to other user's chat client....but, in case of web-based messengers...its different port or shud i say u hv to go through the site then, to the other user's client, simply put, its just passing many blocks......use any chat client instead...