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20.3.2 Finer Grained Control

This pattern can be repeated. We can give ownership of different branches un- der /usr/local to other groups to allow control to be doled out in small sets.


20.4 INSTALLING JBOSS


Using a platform-neutral system like Java has both advantages and disadvan- tages. A disadvantage is that, generally, Java products don’t use the traditional installation mechanisms of your native platform. You don’t install an RPM or a DEB. But this is somewhat offset by the fact that all a Java application needs is for its classes to be arranged in a particular pattern on the filesystem. In other words, all you need to do to install JBoss is to unpack the tarball.

You did the hard part already. Since you have created the group and made yourself a member of that group,8 any member of the group can install the product:


$ cd /usr/local

$ tar xzvf jboss-3.2.3.tgz jboss-3.2.3/lib/

jboss-3.2.3/client/ jboss-3.2.3/docs/ jboss-3.2.3/docs/dtd/

jboss-3.2.3/docs/dtd/html-svg/

...

...

etc.


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8. Group membership is established at login. It may be necessary to log out and log back in to take advantage of a newly created group. There are other obscure ways, such as running a sub- shell with the login argument or running su -, but the simplest is to log out and log back in.




TIP

At this point we suggest using one more Linux filesystem trick. The tarball un- packs into a directory whose name includes the product version—in this case, jboss-3.2.3. In many cases, you will want to be able to have more than one version of JBoss installed on a box simultaneously, either because you need to port projects from one version to another, or perhaps because you need to de- velop applications that will run on different versions on different target servers. To make your life easier, create a symbolic link to a generically named directory, such as jboss, and have that symlink point to jboss-3.2.3. Then you can write your startup and shutdown scripts to use the jboss pathname. You can then switch to another version by changing where the symlink points:


$ cd /usr/local

$ ln -s jboss-3.2.3 jboss


This process is discussed in detail in Section 6.2 in the context of switching between Java SDK versions.


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20.5 THINGS THAT MAKE IT GO


In order to explain how to integrate an Open Source application server into your system, we have to do a little Linux Sysadmin training. We need to show you how server processes are generally managed on Linux systems.