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Common Server-Side Languages
The beauty of Web services being platform-agnostic is that we can use any language to develop them - although there are features to watch for when choosing a language. While a Web service can return data in any format, the title of this chapter is "Building AJAX-Friendly Web Services" and our examples will be returning XML or JSON. In keeping with that philosophy we'll look at languages with inherent XML support or a JSON library.

Language Rundown
We'll briefly touch on several of the more common languages that can be used to create Web services and support XML and JSON. Debating the merits of one server-side programming language over the other is as productive as a debate over the best operating system. We'll provide some basic information about several languages, but in the end the decision of which language to use will fall to you.

PHP
There are a number of JSON libraries freely available for PHP:

Zend_Json is part of the Zend Framework, which is currently available as a preview release from http://framework.zend.com/.

JSON-PHP is PHP implementation of JSON.

PHP-JSON is a C implementation of JSON-PHP that can be compiled and installed as a PHP extension. It's significantly faster, but will require root-level privileges on your Web server or a cooperative administrator. It can be downloaded from www.aurore.net/projects/php-json/.

We'll use the XMLRPC extension with our PHP Web services. PHP also has a SOAP extension available. The XMLRPC extension is poorly documented and you may find it easier to use XMLRPCEPI- PHP, which is at http://xmlrpc-epi.sourceforge.net/. More information about XML-RPC can be found at www.xmlrpc.com/. The PHP manual for XMLRPC is located at http://php.net/xmlrpc. The PHP manual for the SOAP extension is online at http://php.net/soap.

Perl
There are several Perl modules for JSON and XML-RPC:

JSON modules can be found at CPAN at http://search.cpan.org/dist/JSON/.

XMLRPC::Lite provides its own XML parser http://search.cpan.org/search?module=XMLRPC::Lite.

RPC::XML requires XML::Parser. http://search.cpan.org/dist/RPC-XML/.

ColdFusion
Jehiah Czebotar has written a JSON library for ColdFusion that can be downloaded from http://jehiah.com/projects/cfjson/.

ColdFusion has native XML and SOAP support as documented at http://livedocs.macromedia.com/coldfusion/7/htmldocs/00000372.htm.

One thing that ColdFusion lacks is a decent XML-RPC parser. Thankfully Roger Benningfield has created one available at http://mxblogspace.journurl.com/users/admin/?mode=article&entry=763. With examples from his original post at http://support.journurl.com/users/admin/index.cfm?mode=article&entry=362.

This content is reprinted from Real-World AJAX: Secrets of the Masters published by SYS-CON Books. To order the entire book now along with companion DVDs, click here to order.