Potential Applications of Expat4D

One of the things I hear most commonly said about XML is that it's a cool technology but without an application. This is changing at an amazing rate at the moment and XML is becoming more than just a buzz-word.

So where could XML and Expat4D be of use to 4D developers? We hope that the demonstration database gives some inspiration into this, but here are some other ideas.

Intercommunication between different systems

Many software vendors are now implementing XML based interfaces to their systems. For example, in the health sector, HL7 is becoming more widely supported as a means of hospital systems to exchange data, this standard being based on XML.

Oracle and Microsoft are showing a firm commitment to XML with both products now having XML import and export facilities. 4D currently has no support built in for importing XML based data although with 4D it is possible to write a fairly fast XML parser using just native code. Expat4D makes it much easier to create XML importing processors in 4D which are much faster than writing the equivalent in 4D, and also much more flexible.

Generating XML in 4D has never been a particular problem, but until now, there has been little in the way of a good API for generating highly structure documents. The xmlObject module will hopefully start to change this very soon. The xmlObject module doesn't require Expat4D unless you want to convert existing XML documents to objects, but it does require ObjectTools, a must-have plug-in for all 4D developers.

Translating XML to Other Formats

There isn't that much choice in XSLT processors for 4D at the moment without using a Java based one, but using Expat4D you can do quite a bit in the way of translation. The Demonstration database shows some ideas for converting XML to 4D Write Areas and HTML. For certain web applications it may be advantageous to store the content of your site in XML documents, then using templates and an XML processor, convert the content into the HTML for your site.

You could even write a fully blown XSLT processor in 4D using Expat4D, but I wouldn't advise that you did that, as it's probably easily to port an existing library and wrap it into a 4D plug-in as we did with Expat4D.