This example shows how to enact Ponder2 external communications and also XML processing using XPath expressions. From http://www.xmlblaster.org/
XmlBlaster is a publish/subscribe and point to point 100% Java based MOM server (message-oriented middleware) which exchanges messages between publishers and subscribers. The message is described with XML-encoded meta information. Messages may contain everything, GIF images, Java objects, Python scripts, XML data, a word document, plain text - just anything.
Communication with the server is based on socket, CORBA (using JacORB), RMI, XmlRpc, HTTP or email, clients are free to choose their preferred protocol. Other protocols like SOAP may be plugged in.
Subscribers can use XPath expressions to filter the messages they wish to receive.
This example show how to subscribe to xmlBlaster and receive xmlBlaster messages which can then be turned into Ponder2 events. Conversely Ponder2 events can trigger a policy which propagates the events into xmlBlaster.