You are correct to point out that all these things are in the Programmer's Manual: The fact that the actual format of the message ends up as either XML or Java (page 28): anonymous wrote : As mentioned previously, JBossESB supports two serialized message formats: MessageType.JBOSS_XML and MessageType.JAVA_SERIALIZED. In the following sections we shall look at each of these formats in more detail. The fact that TextBody, ObjectBody et al are not accessible as the "default location" (page 23): anonymous wrote : It is important to realise that these extensions do not store their data in the default location; data should be retrieved using the corresponding getters on the extension instance. The fact that everything else expects the data in the "default location" (page 22): anonymous wrote : By default, all JBossESB 4.2.1GA+ components (Actions, Listeners, Gateways, Routers, Notifiers etc) get and set data on the message through the messages "Default Payload Location" The fact that MessageFactory is abstract (page 27): anonymous wrote : public abstract class MessageFactory { ... I'm just trying to say that these questions remain even after reading the documentation, going through the examples that ship with the ESB (which are VERY useful by the way) and going through the forum reading posts like: http://www.jboss.com/index.html?module=bb&op=viewtopic&t=116278 http://www.jboss.com/index.html?module=bb&op=viewtopic&t=116445 To an inexperienced user, it is not clear how to approach the subjecto of "message" definition. I was sidetracked on MessageFactory being abstract because I called its static getInstance() method and got a reference ot something that could create messages. See http://www.jboss.com/index.html?module=bb&op=viewtopic&t=142011 for how I came to do that. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4176103#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...