Best approach to developing a cross-browser JavaScript widget that populates from a MySQL database?

I'm currently researching the best way to approach building a JavaScript widget someone can embed on their site, which would retrieve and display information from an external MySQL database.

The gist of the widget would mimic the needs/functionality of Twitter's widget (http://twitter.com/about/resources/widgets), where it uses some combination of JavaScript, PHP and/or AJAX an开发者_高级运维d retrieves information from a MySQL database with secure (or at least somewhat safe) cross-browser access. Does anyone have thoughts or ideas on the best and most reliable way to approach something like this?

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Here is a great guide to building a cross-domain widget: http://alexmarandon.com/articles/web_widget_jquery/

The hard part is the Javascript side; the server side can be written in PHP, or Python, or Ruby or whatever. Your google search should include the term "javascript widget" to get more articles like this one.

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Should be simple. Encapsulate your widget entirely in a JS file if possible (minus images) and use AJAX for calling a REST or SOAP (probably want to stick to REST) webservice for any data access you need.

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IFRAME, just use a iframe. you have

• native sandbox
• control over your environment
• no updating your widget for your users if there is a new browser. You just update your code in your iframe.
• Everyone uses this method ( Google+, Youtube, Facebook, Twitter )

its a win win situation.