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Java Forum / General / March 2008Design pattern question
Hello, We are going to develop an application that will process incoming JMS messages. The application will receive JMS messages, process them based on their types, and reply by sending a new JMS message with usefull info (at least I hope. This application will run in a EJB container (parhaps GlassFish). Some messages processing need db access. In the future, new message types (and new processing) will be added. Are there any design patterns that can help us for dynamically adding such logic into the application. Thanks very much, Olivier On Mar 2, 12:44 pm, Olivier Scalbert <olivier.scalb...@algosyn.com> wrote: > Hello, > [quoted text clipped - 15 lines] > > Olivier Hi Olivier, There isn't a single pattern to do all that you require...as such a beast wouldn't be a good pattern. You will need to use several patterns together... You will probably be automatically using a publish/subscribe pattern when handling the JMS new message event. The processing of this event would naturally fit any of the Behavioural Patterns, but I would look at the Strategy and Command Patterns. HTH Andrew On Sun, 02 Mar 2008 13:44:22 +0100, Olivier Scalbert <olivier.scalbert@algosyn.com> wrote, quoted or indirectly quoted someone who said : >Are there any design patterns that can help us for dynamically adding >such logic into the application. Try just reading a bit about each pattern and see if you can see how it might solve part of your problem. See http://mindprod.com/jgloss/designpatterns.html -- Roedy Green Canadian Mind Products The Java Glossary http://mindprod.com Thanks for the help. I definitively need to read Core J2EE Design Patterns ... The J2EE application will contain different message transformations. The mapping between messages types and transformations will be configured via a table. The main problem is that user wants to be able to add dynamically new transformations (java code or jar files) into to EJB container. No idea of how to do that ... Olivier > On Sun, 02 Mar 2008 13:44:22 +0100, Olivier Scalbert > <olivier.scalbert@algosyn.com> wrote, quoted or indirectly quoted [quoted text clipped - 12 lines] > The Java Glossary > http://mindprod.com On Mon, 03 Mar 2008 22:33:48 +0100, Olivier Scalbert <olivier.scalbert@algosyn.com> wrote, quoted or indirectly quoted someone who said : > The main problem is that user wants to be able to add >dynamically new transformations (java code or jar files) into to EJB >container. No idea of how to do that ... The usual technique is to use a delegate that implements some interface. The Visitor pattern uses a delegate which might be a way to get your head around the way they work in a simple case. Think about how Sun handles JDBC drivers or JCE implementations. The implementations implement a standard interface. Then you can dynamically load an implementation by name, register it, and select it. You can put your loadedl/available implementations into a HashMap looked up by name (class name). see http://mindprod.com/jgloss/delegate.html -- Roedy Green Canadian Mind Products The Java Glossary http://mindprod.com Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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