Pure Javascript and HTML app & deployment via CDN ... good idea?

A big and general question, though NOT a discussion

Me and a friend are discussing a web application being developed. Currently it uses PHP, but the PHP doesn't store anything and it is all OAuth based. The whole thing talks to an independent API. The PHP is really just mirroring alot of the Javascript logic for browsers without Javascript support.

If it were decided to enforce Javascript as a requirement (let's not go into that ... whole other issue)

Are there any technical, fundamental problems serving the app as HTML+Javascript hosted on a CDN? That is, 100% Static javascript and HTML with no server-side logic. As the Javascript is just as capable of doing all the API calls as the PHP. Are any existing sites doing this?

We can't think of any show-stoppers, but it seems li开发者_JAVA技巧ke a scary thought to make a "web" app 100% client side ... so looking for more input.

(To clarify, the question is about deploying using ONLY javascript and HTML and abandoning server-side processing outside the JSON API or whatever)

Thanks in advance!

One issue is with search engines.

Search engine crawlers index the raw HTML source code of a web-page. If you use JavaScript to load new data and generate new content, crawlers won't come into play, so your content won't get indexed.

However, Google is offering a solution for this - read here: http://code.google.com/web/ajaxcrawling/

Other than this, I can't think of any other issue...

Amazon has been offering the service on its S3 for a little while now. http://aws.typepad.com/aws/2011/02/host-your-static-website-on-amazon-s3.html . Essentially this allows you to specify a default index page and error pages. Otherwise you just load up your html on the S3 and point your www CNAME on your domain to the Amazon S3 bucket or cloudfront CDN.

The only thing that is not possible this way is if a user ends up typing example.com instead of www.example.com, you need to ensure that you have your DNS correctly forward these to www. Also the S3 will not be able to handle a naked domain (http://example.com/).

Regarding how good an idea it is, it sounds good to us as well. And we are currently exploring the option. So far it appears to work fine. What we have done is to setup beta.example.com to point to a CDN hosted site (S3) and are testing to see if it gives us everything we need. Performance is great though !