What are the differences between Infobus and the JavaBeans Activation Framework? Why would I choose one over the other?
As far as the Activation Framework goes, this isn't really about sending messages around, but sending data, where the data is flagged with mime types. You then discover the operations you can do on the data, based upon what type it is.
Which of the three you use really depends upon what you want to do. JMS is a standard part of the J2EE, as is the activation framework, so in many cases one of these two would automatically get the nod first.