Configuring Visual Paradigm Server on Tomcat in Gentoo — Sorta

This post might offend some of you as I’m going to write about a piece of proprietary software. It’s software I’ve already discussed before: the UML modeller I’m using on my dayjobs as well as FLOSS work to help me out with design decisions. If you don’t care about non-Free software, feel free to skip this post.

A couple of months ago I discussed the trouble of getting JSP, Rails and mod_perl to play all together in the same pen Apache configuration. The reason why I had JSP in the mix was that the Visual Paradigm software I bought a couple of years ago is (optionally) licenses on a seat-counting floating license, which I much prefer to a single box’s license, as I often have to move around from one computer to the other.

Back in november, it seemed like I was going finally to work with someone else assisting me, so I bought a license for a second seat, and moved the license server (which is a JSP application, or to be precise a module in a complex JSP application) from my local Yamato to the server that serves this blog as well. The idea was that by making it accessible outside of my own network I could use it on my laptops as well as allowing a colleague to access it to coordinate design decisions.

Unfortunately I needed to make it run fast, and at the end of the day I didn’t set it up properly at all, just hacky enough to work… until a Tomcat update arrived. With the update, the ROOT web application was replaced by Tomcat’s own, taking the place of the VPServer application… and all hell broke loose. I didn’t have time to debug this up to today, when I really felt the need to have my UML models in front of me again, so I decided to spend some time to understand how to set this up properly.

My current final setup is something like this: Apache is the frontend server, it handles SSL and proxies the host – – to the Tomcat server. The Tomcat server is configured with an additional WebApp (rather than replacing the ROOT one) for the VPServer application, which means that I have to do some trickery with mod_rewrite to get the URLs straightened out (Visual Paradigm does not like it if the license server is not top-level, but the admin interface does not like if it’s accessed with a different prefix between Tomcat and Apache).

The application does not only provide floating license entrypoints, it also performs duties for three other modules, mostly collaborative designing tools that need to be purchased separately to be enabled, which I don’t really care about. Possibly for this it allows more than just file-based data storage, which is still the default. You can easily select a MySQL or PostgreSQL instance to store the data — in my case I decided to use PostgreSQL, since the server already had one running, and I’m very happy to lift the I/O task of managing storage from the Java process. For whatever reason, though, the JDBC connector for PostgreSQL is unable to connect to the unix socket path, so I had to sue TCP over localhost. Nothing major, just bothersome.

At the end of the day, all I needed to do was fetching the VPServer WebApp package (.zip file), extract it and move its ROOT/ directory to /var/lib/tomcat-6/webapps/VPServer, make the WEB-INF sub-directory writable to tomcat user (I don’t like it but it seems to be required — the code would like to write to the whole directory structure to be able to auto-update, I’m not really keen on that), and then configure Apache this way:

DocumentRoot /var/lib/tomcat-6/webapps/VPServer

Order allow,deny
Allow from all

Order deny,allow
Deny from all

RewriteEngine On

RewriteRule ^/VPServer(.*)$ $1 [PT]

ProxyPassMatch ^/(VPServer|images).*$ !
ProxyPassMatch ^/.*.css$ !
ProxyPass / ajp://localhost:8009/VPServer/
ProxyPassReverse / ajp://localhost:8009/VPServer/

SecRuleRemoveById flameeyes-2

(Before you ask, the SecRuleRemoveById above is just for documentation: the problem was that up to a couple of versions ago, Visual Paradigm left the default Java User-Agent string, which was filtered by my ModSecurity ruleset — nowadays it reports properly more details about its version and the operating system it is running on.)

The end result is pleasant, finally: with all this in mind it should be possible for me to create a (non-QA-compliant, unfortunately) ebuild for the VPServer software for my overlay, to avoid managing it all by myself, risking to forget how to set it up properly. I’m afraid though that it’ll take me much time to properly unbundle all the JARs, but in the mean time I can at least make it easier for me to update it.

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