// Get user transaction (for example, through JNDI)
UserTransaction utx = ...
// Get a node
Node n = ...
// Start a user transaction
utx.begin();
// Do some work
n.setProperty("myapp:title", "A Tale of Two Cities")
n.save();
// Do some more work
n.setProperty("myapp:author", "Charles Dickens")
n.save();
// Commit the user transaction
utx.commit();