I'm posting this to help polishing the documentation and provide some hints to other newcomers like me. This post is a little long, so I start telling you that there is an happy ending: at the (very) end of the day I managed to make everything work, keep reading on to see how I did it :-)
I discovered only yesterday that new technology called Comet (I happened to think "how does meebo.com work?" and googled for it). I read some articles in various blogs and quickly find out about ActiveMQ which looked perfect as the messaging system for the demo I wanted to set up. I downloaded ActiveMQ 4.0.1 and Jetty 6.0.0 on my Linux box (Debian 3), installed them and started them up. I tested the Javascript interface to ActiveMQ using the demos bundled with Jetty (the ajax activemq-web-demo applications) and then I wrote one myself. Being totally new to Jetty (I'm a Tomcat user) and to JMS or any similar technology I failed to realized that Jetty was using an internal instance of the messaging system. That cost me time when I repeatedly tried and failed to send messages to those web clients from a Java program running from the console of my box. Hower before reaching that point I had to figure out how to write the Java program. I modeled it on the ActiveMQ Hello World application listed at http://www.activemq.org/site/hello-world.html That has been immensely useful, but there are a few things to fix in the code: 1) All the references to org.activemq classes should be changed to org.apache.activemq 2) The line with org.activemq.broker.impl.Main.main(args); fails to compile. That class doesn't exist anymore in any jar file included in the distribution. I found a substitute in org.apache.activemq.console.Main.main(args). I really don't know if this is the right class, but the application compiled, started and connected to ActiveMQ. Actually, when the application starts I get a strange error message: ERROR: java.lang.RuntimeException: Failed to execute start task. Reason: java.io.IOException: Could load xbean factory:java.lang.NoClassDefFoundError I wrote that it is strange because that error doesn't prevent my application from working. Furthermore being able to load something hardly seems an error, hower I'm sure there is a good reason for that choice of words. Anyway, I run into big troubles now. It took me a lot of time to realize that my web clients were connecting to the messaging system running inside Jetty while the Java application was connecting to the standalone instance of ActiveMQ. When I realized it I modified the web.xml file of activemq-web-demo as follows: <param-name>org.apache.activemq.brokerURL</param-name> <param-value>tcp://localhost:61616</param-value> and <param-name>org.apache.activemq.embeddedBroker</param-name> <param-value>false</param-value> That shut down the internal instance and made Jetty connect to the standalone ActiveMQ. I spent another hour before figuring out the correct argument for the createTopic method. The first thing I tried was topic://FOO.BAR, which is what the Javascript interface uses. The Java binding requires only the name so the right line of code was Destination destination = session.createTopic("FOO.BAR") That fixed the application and, joy!, I was able to see the messages sent by my web clients and send messages to them. At the end of the day I had my demo working, and some questions. Maybe somebody can answer them 1) The ajax demos in activemq-web-demo define two variables, topic and membership, and set them to the same value. For instance the chat demo use the value "topic://CHAT.DEMO" for both. The topic is used in amq.addListener('chat', chatTopic, room._chat) and amq.removeListener('chat', chatTopic) and the membership is used in amq.sendMessage(chatMembership, messageText) The question is: the argument of sendMessage is the topic name and it's only a bad design that it uses a different variable? 2) The org.apache.activemq.console.Main class is really what I should use? Is it linked in some way to the error message I'm getting at run time? A final consideration. I lost some time due to some glitches in the documentation, but the fact that I got my demo working in a day being totally new to this technologies is an indicator of the good quality of the software and the community around it (wiki, blogs, etc.), so thanks everybody and I hope to have contributed my 2 cents. -- View this message in context: http://www.nabble.com/A-novice%27s-experience-tf2292008.html#a6366058 Sent from the ActiveMQ - User mailing list archive at Nabble.com.
