I know its not Mediator. Should be either Observer or Adapter.
Here is the reason, why I think it might be adapter.
"A provisioning system then queries data and makes appropriate calls to various subsystems using JMS on MQ Series" -- This means the provisioning system cannot directly call the other subsystems. ie, no way to invoke the subsystems directly. The JMS is acting as a "Messaging Integration" scenario, the bridge between the provisioning system and the other subsystems ( Don't confuse with the
word bridge, bridge pattern is something else). So, Adapter looks to be right choice.
Above logic is why I am saying it be Adapter. But as I am a newbie to Patterns, I need someone to validate this. Experts please help.
Thanks,
Naveen