| By Sam Pullara | Article Rating: |
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| January 7, 2002 12:00 AM EST | Reads: |
8,013 |
Wow. That's what I have to say when I look back at where WebLogic began and where it has gone since then. When I started working at WebLogic, the only core people there were the founders, the president, an administrative assistant, and a lone sales person. Of course, back then our big moneymakers were the JDBC drivers. We always said, "You know, in two months, Oracle/Sybase/Microsoft is going to come out with a great native database driver and we won't be able to make any money in this business. We have to start selling our server." Fortunately for us, we're still able to sell those JDBC drivers, although they're a very small fraction of sales. WebLogic has come a long way in becoming a standards-based, fault-tolerant, scalable platform for building enterprise Java applications. Even our tag line back in those days was prophetic: "WebLogic, Elevating Java to the Enterprise."
So, now developers can buy our server off the shelf, use any tutorial or book that describes J2EE, and build incredible applications without having to build the infrastructure. There were times in the development of WebLogic where I'd step out of server-development mode and sit down and write an application. Inevitably it would lead me to trying to add more services to the platform so others didn't have to build it themselves. It's not true anymore. All the services to write real applications are handed to you - now if only it would architect the application!
Now, I'm sure all of you have used servlets and JSP. Many others have also used EJB. But I'm going to focus on what I believe is the most powerful new service available in WebLogic, Message Driven Beans (MDBs). Ah, the MDB is a beautiful thing. You create a destination (queue or topic), deploy a class that implements MessageDrivenBean and MessageListener, and BLAM! You have a unique application programming model that gives you very powerful messaging infrastructure. The combination of the EJB component model and the JMS messaging model gives you a tool that can be used effectively in a wide variety of applications. For instance, using this programming model, it was very easy to use JavaMail to build an e-mail-JMS bidirectional gateway. Drop a mime message on a queue, it gets sent out as an e-mail message, with retry! Receive a message in your mailbox, it appears as a mime message on a JMS queue in your server. Imagine the possibilities. Message forwarding, filtering, alerts, acknowledgments, all straight to your J2EE application. Combine it with a JSP tag for putting e-mail on a queue, and you get a pretty effective SPAM machine, not that I suggest you do that. E-mail address verification, e-mail-based monitoring, and server control. The best part about it is that the MDB gives you the power to implement gateways like this easily and with all the guarantees that JMS can provide. Another exciting usage of the message driven bean is integration with the all-new and shiny Web service. Business-to-business Web services will have to rely on constructs like the MDB to ensure that messages queued on one side arrive safely on the other in the face of network outages and error conditions. Combined with our out-of-the-box support for destination-based Web services, you can get a system like this up and running in no time, including the integration with partners that are using .NET, Apache, and many more.
In each issue I'm going to focus on a specific WebLogic technology and an associated cutting-edge technology, and how you as a developer can integrate the two and what you can expect in the future. I hope that today's rant from the soapbox encourages you to investigate the new features in WebLogic and to view them in the context of current technology.
Published January 7, 2002 Reads 8,013
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Sam Pullara has been a software engineer at WebLogic since 1996 and has contributed to the architecture, design, and implementation of many aspects of the application server.
e-mail: sam@sampullara.com






























