AJAX has become the core component of many web applications around us. And its fairly easy to handle AJAX now a days, with the help of various javascript libraries (ex: jQuery, Prototype, Mootools, YUI, etc). But there is one security issue that web browsers impose in doing AJAX calls - they don’t let you do AJAX calls in web servers different than yours. That means, if your script is in www.mydomain.com and you’re trying to do AJAX call to www.anotherdomain.com/get.php, then the browser will through error like: “Error: uncaught exception: Permission denied to call method XMLHttpRequest.open”.

Now, there are a number of solutions to this problem. Instead of explaining them all to you, lemme provide you the simplest one: using a PHP transport file. If you already know the thing and just need the script, download from here.

Others, let’s see an example implementation first.

Example use

   1: xmlHttp.onreadystatechange=function()

   2: {

   3:     if(xmlHttp.readyState==4)

   4:     {

   5:         alert(xmlHttp.responseText);

   6:     }

   7: }

   8:  

   9: xmlHttp.open(“GET”, ‘http://myserver.com/transport.php?action=’ + 

  10:                     urlencode(‘different-server.com/return_call.php’) +

  11:                     ‘&method=get&data1=101&data2=pass’, true );

  12:  

  13: xmlHttp.send(null);

Now, lets see how it works:

1. The script makes an AJAX call to the myserver.com/transport.php with a few parameters:
   • action = the target URL you need to fetch, from a different domain
   • method = the HTTP method (post/get)
   • data1, data2 = sample parameters for using as either query-string or POST fields
2. When the request is received by transport.php, it uses cURL to make a call to the page mentioned in action.
3. Based on the method, it either makes a GET request or a POST request. In both cases, it sends the extra parameters that are sent.
4. After the response is received, transport.php echoes it. So, you have what you need!

Download

transport.php Cross-Domain AJAX call transporter. Downloaded: 806 times

Comments and suggestions are most welcomed

This is a wrapper HTTP class that uses either cURL or fsockopen to harvest resources from the web. It supports a handy subset of functionalists of HTTP that are mostly needed in day to day coding. Scripts who need to communicate with other servers will find it useful. If you’re looking to invoke any RESTful API and don’t want to bother adding a bunch of libraries for that simple thing, just put this class and you’re set.

Detailed documentation can be found here. And you can download the source from here.

UPDATE: Class added in Orchid - “PHP framwork for the rest of us”

Features

• Can use both cURL and fsockopen.
• Degrades to fsockopen if cURL not enabled.
• Supports HTTP Basic authentication.
• Supports defining custom request headers.
• Supports defining connection timeout values.
• Supports defining user agent and referral values.
• Supports both user-defined and persistent cookies.
• Supports secure connections (HTTPS) with and without cURL.
• Supports adding requests parameters for both GET and POST.
• Supports automatic redirection (maximum redirect can be defined).
• Returns HTTP response headers and response body data separately.

Example 1 - Simple Get (Facebook Application List)

   1: <?php

   2:  

   3: include_once(‘class.http.php’);

   4:  

   5: $http = new Http();

   6:  

   7: $http->execute(‘http://www.facebook.com/apps/index.php?sort=6′);

   8: echo ($http->error) ? $http->error : $http->result;

   9:  

  10: ?>

Example 2 - Invoking Yahoo Term Extraction API

   1: <?php

   2:  

   3: include_once(‘class.http.php’);

   4:  

   5: $http = new Http();

   6:  

   7: $http->addParam(‘appid’   , ‘a_really_random_yahoo_app_id’);

   8: $http->addParam(‘context’ , ‘I am happy because I bought a new car’);

   9: $http->addParam(‘output’  , ‘xml’);

  10:                         

  11: $http->execute(‘http://search.yahooapis.com/ContentAnalysisService/V1/termExtraction’);

  12: echo ($http->error) ? $http->error : $http->result;

  13:  

  14: ?>

Example 3 - Logging into Basecamp (without using cURL!)

   1: <?php

   2:  

   3: include_once(‘class.http.php’);

   4:  

   5: $http = new Http();

   6:  

   7: $http->useCurl(false);

   8: $http->setMethod(‘POST’);

   9:  

  10: $http->addParam(‘user_name’, ‘emran’);

  11: $http->addParam(‘password’, ‘hasan’);

  12:  

  13: $http->setReferrer(‘https://someproject.projectpath.com/login’);

  14: $http->execute(‘https://someproject.projectpath.com/login/authenticate’);

  15:  

  16: echo ($http->error) ? $http->error : $http->result;

  17:  

  18: ?>

Example 4 - Getting a protected feed

   1: <?php

   2:  

   3: include_once(‘class.http.php’);

   4:  

   5: $http = new Http();

   6: $http->setAuth(‘emran’, ‘hasan’);

   7:  

   8: $http->execute(‘http://www.someblog.com/protected/feed.xml’);

   9: echo ($http->error) ? $http->error : $http->result;

  10:  

  11: ?>

Download

class.http.php HTTP Class for PHP (supports both cURL and fsockopen) Downloaded: 983 times