The JMS 1.1 specification, section 6.11.1 "Durable TopicSubscriber" states:
A client can change an existing durable subscription by creating a durable TopicSubscriber with the same name and a new topic and/or message selector, or NoLocal attribute. Changing a durable subscription is equivalent to deleting and recreating it.
However the javadoc here for the Session method createDurableSubscriber(Topic topic, java.lang.String name, java.lang.String messageSelector, boolean noLocal) states that
A client can change an existing durable subscription by creating a durable TopicSubscriber with the same name and a new topic and/or message selector. Changing a durable subscriber is equivalent to unsubscribing (deleting) the old one and creating a new one.
The latter text uses an almost identical sentence but does not mention the effect of creating a durable subscriber with a different value of the noLocal flag.
This is contradictory and needs to be clarified. What is the effect if creating a durable subscriber with a different value of the noLocal flag than was used when the durable subscription was created?
I propose that we should interpret the javadoc as being correct and change the spec to match. The NoLocal flag determines whether messages sent using the connection that created the durable subscription should be added to it. Its significance ceases when the connection is closed. If the second call to createDurableSubscription uses a different connection then the value of noLocal that it specifies is completely independent of the previous value and does not render the durable subscription invalid. It is therefore not necessary to delete the durable subscription and create a new one.