What is the "one-document-per-URL paradigm"?

what does "one-document-per-URL paradigm" mean with reference to web d开发者_JS百科evelopment..

That if you go to a URI, you get a document, and you always get the same document.

The best way to explain it is to describe how to break it - which is usually achieved with frames or Ajax.

Frames gives you a document containing a frameset. You click a link and the page loaded in one of the frames changes. You are viewing "About" instead of "Home" but the URL in the address is unchanged so if you copy the link or bookmark it, you end up at "Home" instead of "About"

You get the same effect when Ajax is overused.

It usually means that under one URL, you should serve only one resource.

Example of right uses: Page with one news article, information about one specific product, etc.

Next step from there would be to allow user to see same resource in multiple ways. Ie, by visiting example.com/some/url?xml visitor is able to get information about given resource in XML format. If your page was list of resources, you could offer ?rss form of your list... etc.

In contrast to good uses, bad use would be that different things appear under same URL. For instance, when you have page to search for some product, you would have to avoid using POST for searching, because then you would be violating this principle (URL always leads to first search page, not to result page).

I hope I provided some answer and did not confuse you. :)