As per Service-Oriented Architecture (SOA) definition, an architectural style that supports service-orientation.
Does that mean only web services (SOAP and REST) are treated as part/backbone of SOA? What about messaging services?
No and yes.
A webservice can be designed in a service orientated way, but a "service" (SOA) describes functionality, a bundle of business logic.
Service orientated architecture means, you have different systems, different users, and the way you implement your business focuses on the whole beeing a service.
The former (SOA) is something abstract, a paradigm, a commitment on how to implement something, the latter is technology (REST, SOAP, ...).
In conjunction with webservices, the "how to" is often described using WS-Business Process Execution Language (short: BPEL). It is used to orchestrate providers and consumers and allows high-traffic processes to scale in the cloud.
Consider your bank, processing many business steps per second in a very standardized fashion; using standard services like transfering money from one account to another.
Talking about Java and JMS, Oracle has a tutorial up: This example shows the steps to create a simple JMS queue in WebLogic Server 11g for testing purposes.