Eli Grey

pmxdr standard documented

I decided to make some detailed documentation on the pmxdr standard used for pmxdr client and host interaction. You may use the standard to implement your own pmxdr client and host libraries. This is particularly useful for websites that don’t want to follow any HTTP access control headers and want to make their own host library implementation use different methods of verification than the reference implementations. The standard is dedicated to the public domain just like every standard I have released so far.

I also modified the demo to automatically do every test so you don’t have to click any buttons to initiate tests.

pmxdr: postMessage cross-domain request library

pmxdr is a cross-domain HTTP request JavaScript library. pmxdr stands for postMessage cross-domain requester. As the name implies, it makes use of the HTML5 postMessage API to make HTTP requests. It requires that a pmxdr host be on the target domain and it respects all HTTP access control headers, even on browsers that don’t support them but do support postMessage, like Firefox 3.

You can download the pmxdr client library and the pmxdr host library (includes an example .htaccess file to help Apache users with PHP set it up) under the latest GNU GPL license and an MIT-style license. The host library must be able to be accessed from /pmxdr/api to be able to interact with the client library.

Read more at the pmxdr project page and try out the demo of it in action.

The following is a very simple example of how to use pmxdr to do a cross-domain POST request (impossible with the normal method of inserting a script tag):

// The requesting domain is example.net
// example.net doesn't want to give any control to example.com
  method   : "post",
  uri      : "http://example.com/search.json",
  data     : "q=foo",
  callback : loadSearchJSON

Usually, in this hypothetical example, example.net would have to put a script tag with an src of http://example.com/search.json?q=foo&callback=loadSearchJSON and give example.com full control of example.net. This provides a secure cross-domain way to use APIs like this.