This week's book giveaways are in the iOS and Features new in Java 8 forums. We're giving away four copies each of Barcodes with iOS: Bringing together the digital and physical worlds and Core Java for the Impatient and have the authors on-line! See this thread and this one for details.
Do you have to implement the client side, server side or both? Are the XML messages SOAP messages or are they custom XML messages?
For the server side: Simply write a servlet that reads the request in XML format and configure your web server / servlet container for HTTPS - you'll need to look in the documentation of your specific web server for that.