In his latest blog post, Adam Trachtenberg looks into the world of web services and comes out with three topics - SOAP, axis2, and SDO. He chooses to focus, though, on the last of these after working with it to really get a feel for what it can do.

n my role as eBay Platform Evangelist, I spend a lot of time exploring different XML technologies. SOAP is obviously the big one. No, it's not PEAR::SOAP or NuSOAP; it's axis2.

He talks a bit about what axis2 is and the need it fills in the web services world. He also talks about how it's been developed (not copied after SOAP, but more of a fresh start that happens to do the same things). After this quick look at axis2, though, he gets into the head of the post - SDO.

The other PHP XML extension I've been hearing a lot about is SDO. SDO is an attempt to provide a standard data interface regardless of the backend datasource. So, for example, you can interact with XML data in the exact same manner as information pulled from your database.

Adam decided to give it a try and see how it interacted with the eBay API with some simple code examples. The first of which looks through eBay Motors and finds the title and mileage for each of the items grabbed. It worked well, and didn't require too much more development than the SOAP predecesor, but there were a few quirks that made things a bit more difficult (like SDO's inability to completely consume a WSDL file and understand a SOAP service's functionality).