Message Queue 4.2 administered objects have been enhanced with new attributes, and some attributes have been renamed from earlier versions. Although you can continue to use object stores and administered objects created in Message Queue 3.6 or 3.7, it is best to upgrade your administered objects after installing Message Queue 4.2.
When performing an update operation, the Administration Console (imqadmin) and the Object Manager utility (imqobjmgr) will automatically convert administered objects from Versions 3.6 and 3.7 to Message Queue 4.2 form, using default values for the new attributes. The Message Queue 4.2 client runtime will also look up and instantiate administered objects from those earlier versions and convert them for use by Message Queue 4.2 clients, but this will not convert the objects permanently in the object store in which they reside.
Existing Message Queue clients that directly instantiate administered objects are compatible with Message Queue 4.2. For attributes that have been renamed in Message Queue 4.2, the old names will still work. (Recompiling the client with Message Queue 4.2 will show which attributes have been renamed.) However, clients will need to be rewritten if they are to use any of the new administered object attributes. Similarly, scripts that start Java clients and set administered object attribute values using command line options are compatible with Message Queue 4.2,but must be rewritten in order to use the new attributes.