First off, the ObjectInputStream is just not what you want at all. That's really only useful for reading back
Java objects that were previously serialized using an ObjectOutputStream. Now, if your difficulty is getting the bdb block, then it's no problem. Java has a lot of support for parsing XML. I'd suggest using a DOM parser here. On the other hand, if your difficulty is parsing the CBEFF data that's in that block, you're going to need to do some research. It's possible that someone has made a Java library to parse these messages for you, but it's also possible you'll have to write your own. It's not part of the standard Java APIs.