The following restrictions on transactions are enforced by the container and must be observed as session beans are developed:
A session bean can participate in, at most, a single transaction at a time.
If a session bean is participating in a transaction, a client cannot invoke a method on the bean such that the trans-attribute element in the ejb-jar.xml file would cause the container to execute the method in a different or unspecified transaction context or an exception is thrown.
If a session bean instance is participating in a transaction, a client cannot invoke the remove method on the session object’s home or component interface object or an exception is thrown.