Allowing remote update of
the DimensioneX engine
hosted under Tomcat 4
KB Article n. 015
Date: May, 15th, 2003
Originally for: Tomcat 4 - any DimensioneX version
This article explains how to allow remote update of a
DimensioneX engine, hosted on Tomcat 4
We will assume here that you have:
- Java2 installed and working (JRE or SDK this is not
- Tomcat 4 (a stable version) installed and working.
- DimensioneX properly installed and working.
We suppose in this article that you want to modify this installation so that a specific user
is able to remotely update the DimensioneX engine and games without bothering the
The goal can be accomplished by allowing the remote game
administrator to remotely manage the dimx folder, contained in your
tomcat_installation/webapps folder. This implies:
- The dimx folder must be remotely accessible via FTP so you
have to set up an FTP service and account which has read/write access on
- This already gives the remote administrator the possibility to
update the game files (DXW) the skins files (DXS) the game server properties
(worldnav.properties) and all the remaining stuff except for the game
engine's Java class files. Reason for this is that the game engine classes
are usually contained in a single JAR file, located in the dimx/WEB-INF/lib folder,
which gets loaded once at Tomcat's startup.
How to solve it
In order to overcome this obstacle you need to take advantage
of a Tomcat's feature named Servlet Reloading.
Basically, with this feature you
can replace any servlet and class file by simply overwriting the old with the
new version, without any problems of file locking. Furthermore, the Tomcat 4 server
will automatically detect the changed classes and will reload them so the game can be
restarted in the updated game engine.
You need to take the following steps:
- Stop the Tomcat server
- In your Tomcat 4 installation folder, locate the conf
- There, you will find a server.xml file. Make a backup copy
of it and then open it in a text editor.
- Using the Find function of the text editor, look for the
words: Root Context
- You will find out that this string appears inside a
comment. Now create some space above this comment and insert the following
lines in bold, until the text looks as follows:
Enables servlet reloading by default.
<DefaultContext reloadable="true" />
<!-- Tomcat Root Context -->
- Save and close the server.xml file.
- Now locate the Tomcat_install/webapps/dimx/WEB-INF folder.
It has a lib and a system folder in it.
- Open the lib folder and rename the JAR file you will find
so that it has a .ZIP extension. This is sufficient to open it with a double
click (you need to have WinZip installed for this)
- Once you have opened the ZIP, you will see the classes
contained in our former JAR file. Now extract all the classes while preserving
the folder structure in a new folder named:
Like this, you will create a new folder named classes and place
all the contents of the JAR file in it.
- Now you just close the ZIP file and delete it or move it
somewhere outside the Tomcat webapps tree. The game engine classes
are now available from the classes folder. Double check that the classes
folder contains a cleoni folder. If it is not like this, it means you
have unpacked the ZIP without preserving the folder structure, so you need
to redo step 9 above.
- Restart Tomcat.
If you performed the steps above correctly:
the game engine classes (contained in the dimx/WEB-INF/classes
tree) can be updated anytime via FTP. Tomcat sees the change and reloads them
the game files, skins, properties and all the remaining stuff
are in the dimx/WEB-INF/system tree and can be updated anytime via FTP. To make
the game engine to reload them, just use the admin's interface by using an URL
- DimensioneX runs on Tomcat 4. You can obtain hosting from
anyone offering a web space under Tomcat 4.
- To update the game engine and game files, an FTP account
should be set up to allow file upload to the dimx tree.
- Normally, Tomcat 4 needs to be restarted each time the game
engine is updated. Moreover, that files are locked during normal server
running so they cannot be updated via FTP.
- By following the steps described in this article, you take
advantage of Tomcat 4's Servlet Reloading feature, so your DimX
installation can be entirely managed by a remote admin via a simple FTP