computer science

OpenJMS

OpenJMS is a computer science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand OpenJMS rather than just read about it. In short: OpenJMS is one of the major providers of Java Message Service API, which implements Sun Microsystems' Java Message Service API 1.1 Specification. The current release is OpenJMS 0.7.7-beta-1.

Key takeaways

OpenJMS belongs to computer science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect OpenJMS to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of OpenJMS from memory before moving on to harder problems.

Reference excerpt

OpenJMS is one of the major providers of Java Message Service API, which implements Sun Microsystems' Java Message Service API 1.1 Specification. The current release is OpenJMS 0.7.7-beta-1. Java Message Service is an asynchronous communication mechanism in the distributed system field. It is very helpful in the situation where the distributed components are loosely coupled. Another popular distributed communication technology is Remote Method Invocation (RMI), which is tightly coupled and requires an application to know a remote application's methods. One benefit of OpenJMS is that it is vendor neutral. Because the Java JMS specifications do not specify a wire protocol, each vendor's JMS implementation is distinct and not interoperable with others. Since JMS's are normally released as part of an application server provider this makes the implementation of a JMS vendor specific to that application server. OpenJMS is not dependent on any given application server and therefore can be a common interface between users of different vendors. Users of various application servers can agree to use the common OpenJMS implementation for their interoperability layers.

Further reading Myerson, Judith M. (2002). The Complete Book of Middleware. CRC Press. p. 103. ISBN 0-8493-1272-8. Monson-Haefel, Richard; Chappell, David A. (2003). Java Message Service (Edition française) (in French). O'Reilly. p. Ch. 9. ISBN 978-2-84177-208-7.

Worked examples

Example 1 — a first encounter with OpenJMS

Start with the simplest possible case. Write down what OpenJMS claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In computer science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to OpenJMS before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about OpenJMS ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of OpenJMS

In research: OpenJMS appears in computer science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses OpenJMS in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: OpenJMS is common in secondary-school and first-year university syllabi. It links to neighbouring topics Computing stubs, Message-oriented middleware, so understanding it makes those chapters shorter.
In everyday life: Look for OpenJMS outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study OpenJMS in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what OpenJMS means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain OpenJMS out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is OpenJMS in simple terms?

OpenJMS is one of the major providers of Java Message Service API, which implements Sun Microsystems' Java Message Service API 1.1 Specification. The current release is OpenJMS 0.7.7-beta-1.

Why does OpenJMS matter?

Because it connects several computer science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study OpenJMS?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on OpenJMS.