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Animated GIF vs. Server Push
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Q  Animated GIFs seem to be all the rage these days. Why? What are the advantages (if any) of using an animated GIF rather than a server push?
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A  I'd never heard anyone use the verb "to tax" in casual conversation until I started talking to engineers about server pushes. "No, you shouldn't do it," they'd say, shaking their heads in concern. "It taxes the server."

And indeed it does. For starters, server-push images aren't compressed (animated GIFs are), and because they're run by a CGI script, they can't be cached; every time a user returns to the page or hits Reload, the server has to push out the images all over again (animated GIFs can be served from the cache).

Server pushes are powered by a CGI script that makes the server send a string of pages as though they were one big document. Normally, a server is free to simultaneously process many requests from many clients, but the server push forces it to focus its attention, leaving a single connection wide open for a single client while it loads and runs the CGI script, finds and grabs the images on the server, and pushes the entire series out - sort of like holding your breath while giving birth to a baby (blush). I'm sure you can think of other analogies.

"Well," you might say, "I don't particularly care if the server is having a hard day or not - I just want my graphics to look cool." And at first glance you might think there are compelling reasons to use server pushes instead of animated GIFs: they're supported by more browsers (Navigator 1.1+, Internet Explorer 1.0+, Netscape 2.0 and above, MSIE 3.0 and above) than animated GIFs (Internet Explorer 3.0, Netscape 2.0 and above), and the stream of server-push graphics usually doesn't "hiccup" the way animated GIFs do.

Are animated 

GIFs the 

way to go?

Threads

In reality, though, server pushes are more hassle than they're worth: They are extremely taxing on servers, you need to know CGI scripting (or someone who does) to make them work, and you'll need to bribe the engineers who run your server in order to implement them. In fact, if your homepage is at a university or on an Internet service provider, forget server pushes altogether; you probably don't have access to run a CGI script anyway.

If you ask me, animated GIFs are the way to go. They're cleaner, more efficient, and easier to implement. With GifBuilder, a simple freeware program, you can quickly assemble animated GIFs without any special server access or knowledge of CGI scripting.

GifBuilder's easy to learn and offers pretty good image compression. Eight 10K frames result in an animated GIF much smaller than 80K, and if you isolate only the changing parts of the image, you can make it even smaller. Unfortunately, the program itself often gets a little moody, but that's a subject for another day....

Have fun.

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Emily Tucker is production manager for HotWired's Front Door. Her dad is very proud of her.



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