Cross Domain AJAX

I thought that you might be able to do this but, I also knew it was still JavaScript. So, this is the best [url=http://snook.ca/archives/javascript/cross_domain_aj/]write up[/url] I found, that answered my confused question and a little more. We all know of the proxy method. The JSON method I think uses meta tags and isn’t the cleanest of solutions. The Flash method just made me say, “Duh, I should had though of that.” but then your relying on flash to work. Then I saw I cross domain example using Dojo and iFrames that seemed to work but I saw two things with it: it was slow, from what I read, and I hate iFrames. Enjoy.

[quote="[url=http://snook.ca/]snook.ca[/url]“]Cross Domain Ajax: a Quick Summary
~ in JavaScript ~
2006 | Aug 18

Here are a few of the most popular ways to do cross domain calls via JavaScript: proxies, JSON, and Flash.

Cross domain proxy

This is one of the most common approaches. Your script calls your server, your server makes the call to the remote server and then returns the result back to the client. There are some definite advantages to this approach: you have more control over the entire lifecycle. You can parse the data from the remote server, do with it what you will before sending it back to the client. If anything fails along the way, you can handle it in your own way. And lastly, you can log all remote calls. WIth that you can track success, failure and popularity.

Cross domain JSON

For this to work, the remote server needs to be set up to handle this. It needs to accept an additional parameter: a callback function. Then, to make the remote request, you insert a new script tag into your page with which will allow you to specify a remote URL. The reponse back will load a JSON object as a parameter of the callback function you specified in the request. Yahoo, for example, has implemented this feature in their web services API’s. This is great because you can implement web service calls without ever needing a scripting language on your server. Check out Jason Levitt’s article, JSON and the Dynamic Script Tag, on XML.com for more information.

Cross domain using Flash

Flash, by default, is much like Ajax in that you cannot request data from a remote server. However, you can enable this capability by placing a special XML file on the remote server to accept requests from other domains. With JavaScript’s capability to interact with Flash, we can use Flash as a bridge for sending cross-domain requests. (XML.com has a nice write-up of this technique.) There are still some limitations to this technique, most of which seems to be limited to older versions of Flash. There’s also the issue with users having Flash installed and enabled.

Sub-domains are still cross domains

One point to note and it’s fairly subtle. Plenty of us have our sites running at www.example.com and at example.com. They both point to the very same place. To us, we see them as the same thing. But to an Ajax call, it’s considered cross domain. Therefore, if you have to make an Ajax call to the same server, don’t code the domain as part of the request; just use the path.

The Future

Some have already begun looking into establishing standards that could be implemented into future browsers, such as JSONRequest and ContextAgnosticXMLHttpRequest. JSONRequest seems the most promising but that could be because I prefer JSON over XML and see it as really gaining traction over the next couple years.[/quote]

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