Looking at concepts related to mash-ups, inspired in part by Flickr and in part by Amazon’s Simple Queue Services. Have some notes here, and it’s a work in progress. Basically I am trying to understand how each protocol works, starting with REST as it is found in Zuardi’s Actionscript (REST-based) API for Flickr. Also looking at SOAP and XML-RPC, and SQS Query (used by Amazon) which indeed seems more alike to Flick’r REST than Amazon’s REST is.
Also looking at implementing each protocol in .NET and Java.
To summarize, for REST you use HTTP GET, for the others, POST. Effectively this means that in Actionscript you use XML.send in the first case and XML.sendAndLoad in the second. In .NET, request = (HttpWebRequest)WebRequest.Create(restEndpoint) with the default parameters in the first case, and WebRequest.Create with some parameters set differently in the second case.
There is an open source library that somewhat simplifies XML-RPC in Actionscript. The documentation is not there so I had to spend a couple of hours to get it to work!
For the methods that need authentication in Flickr, the process is just as involved as it is with SQS, but no X.509?
People really seem to like REST with Flickr as I have not found any XML-RPC implementations (I did not search too hard though).
In Java you have to use the URL and HttpURLConnection classes. And there are plenty of XML-RPC implementations in Java.