Problems can happen in the best of families, and software is no exception. If you see an error when you start the server, or when you deploy your own JBoss ESB service what should you do? Here's a set of steps that you should take: an easy way to start is to try to reconstruct the steps that you took before the error occurred. It may be that the root cause of the error was a configuration change or some other form of action that you performed. Remember that if you made a copy of the server profile before you started making changes, you can easily restore it.
If you can't easily identify or remember the cause of the error, then it's time to do some investigation of the logs.
First, examine the server log. Look at the messages that were displayed before or after the error occurred. What sort of things might be in the log? The following are a few examples:
- "Class not found" (CNF) exceptions: These problems may be caused by a missing
.jar, or an incomplete deployment. The root cause of this may be that theCLASSPATHenvironment is not set correctly. Note that, in order to start the server, you don't have to haveCLASSPATHpre-defined. The start-up scripts will do it for you. - "Java not found" exceptions: The root cause of this problem may be that the
PATHenvironment variable is not set correctly. Try to verify that you can invoke the Java runtime from the command line and check its version (java -version). - "Address already in use" exceptions: The root cause of this problem is that another server is already running on the port that the server you are starting is trying to use. By default, JBoss AS, with or without JBoss ESB deployed, runs on port 8080. If you see this error when you are trying to start the server, it's because another server is already running.
- "Illegal state" exceptions: These problems may be caused by an invalid configuration file. Examine the error in the log and if it specifies an ESB validation error, check your
jboss-esb.xmlfile for errors.
If the error that you see doesn't make sense to you, you can always use a search engine to query pertinent information about your error, or ask a question on the user forum and attach your server.log to the post.
Before we move on, it's time to see what you've learned. Pencils ready? Let's begin!
- JBossESB can run in standalone mode, without being deployed to an application server. True or false?
- Name the (3) JBossESB distributions.
- You can always get 24/7 support for all JBoss community projects simply by calling a super secret 1-800 telephone number. True or false?
- The best way to get help on a question you have on JBoss community projects is to immediately make a vague post to the projects' forum. True or false?
- What is a server "profile"?
- How do you make a copy of a server profile, and why would you want to have a copy if the software is free?
- The server logs are a waste of disk space. You should always delete the log files. True or false?
- What is an MBean? And how does the JBoss JMX make it easy for you to use them?