The making of an OSGI based IRC Bot

I've released the source code of JerkBot, an IRC bot based on Jerklib and OSGI. JerkBot source code is a multi-module maven project. It's not some OSGI/Java blueprints as I'm no OSGI expert, plus JerkBot is basically a 24 hours effort without bug fixes.

The library itself is distributed under BSD license, but the bot provides plugins such as SVN for example using SVNKit , which is subject to other licensing terms.

The bot uses Declarative Services for OSGI and Java technologies such as :

• Apache Lucene for Javadoc Search
• Quartz for job scheduling(session tracking, pending registrations, etc.)
• Javamail to send emails for user registration
• EclipseLink for persistence
• A subset of JAAS for security
• JMX for administrative commands (accessible through JConsole or through the bot jmx command)
• The usual Jakarta libraries and couple of other libraries

I didn't provide scripting languages to the bot for security reasons, there's only JMX. I would prefer to offer scripting languages in a secure way with a custom SecurityManager to prevent drama from happening :-).
Let's say scripting is enabled, and someone accidently tries one or all the following instructions in a scripting language.

• File("/somepath").delete()
• System.exit(0)
• Download("http://website/hugefile.iso").saveToDisk();

JerkBot was roughly a one day effort with 4 rewrites(1 full day each), and of course bug fixes time to time:

• The first version was using traditional OSGI, well not so traditional :-), with BundleActivators service trackers and listeners, etc.
• The second rewrite used Declarative Services with manually written XML descriptors
• The third rewrite was based on Felix IPOJO. I would have preferred to use IPOJO, but found some annoyances(abstract based classes, JMX flexibility, etc.).
• The last rewrite is using Felix SCR but with annotations to generate XML descriptors for components. Simplify code, remove unnecessary abstractions, consistent logic, etc.

I'll be providing the binary distribution soon. The binary distribution contains everything necessary to run the bot : OSGI configuration files, Bot configuration, jars, a user/developer guide, etc.

What the bot doesn't provide is a logging mechanism, for IRC channel logs. To do it right, I think it would be better to create a new project. In my opinion, when a bot logs channel it should have, if possible, the following features:

• Configurable tasks to schedule flexible timed delivery of existing logs(local filesystem, ftp, samba share, ssh, http put, etc.)
• Configurable log format(HTML, CSV, TXT) with optional generation of html logs or text logs.
• Database storage or any other persistence mechanism(Apache Lucene Index vs flat text files, database logs, etc.)
• Ability to stop/start logging for every channel
• Optional Web front-end to publish logs(Could be a static HTML pages with Javascript search, JSF, Wicket, GWT, Rest interface + Apache Lucene or a DB for search).
  

Providing a quick and dirty plugin for channel logs would be trivial but not flexible :-). I started implementing it, but I decided to stop there.

The first draft of the bot manual can be found in the svn repository. Please bear with me for grammar and spelling mistakes, it was a written very quickly at early AM :-)

In JerkBot plugins are provided by OSGI bundles. I learned a lot from my previous experience with JPF when writing XPontus.

For now the bot is sitting on irc.freenode.net in the ##swing channel, running on an old laptop(FreeBSD-CURRENT).

Which one is the best?

You've probably heard it many times, in various circumstances. What was your answer?

That trivial question may(or not) have been subject to a long answer with hopefully credible reasons. "The problem is ... Many tools provide XXX ... This tool is the best, in this case, as ...".
But you're the expert! The reasons motivating your choices should be obvious to anybody else without having a long discussion!

There is no best, there are needs and there are constraints to reach particular goals(short, medium or long term). All those variables usually fits in to a vision.

If there were a best, anyone who could afford it, would have it.

No, no why would I want to use crap seriously?? So many tools already suck and people keep providing more crap. Maybe I should suggest that they stop already, as there are many similar great tools out there.

A typical conversation about choosing a Linux distribution
Q: "What's the best Linux distribution? Ubuntu?"
A: "Wut??? Hell no, it's Debian and all the rest is crap including the derivatives."
Q: "Why?"
A: "Because Ubuntu doesn't ... and because I say so :-)"
Q: "But Ubuntu is easy and Debian is not user friendly!"
A: "Really? Not really .... Ah, I guess I just like things when they're complicated, must be the geek feeling."

A tool can meet needs but not all the constraints and vice-versa and what you'll probably be looking for is a balance.

• Memory usage vs tons of features
• Usability vs complexity/too much flexibility
• Easily understood vs require 5 books + certification + hiring a consultant
• Commercial support vs community support
• Proven stability and acceptance vs the unknown
• etc.

There are simple ways to decide :

• You have a problem to address within constraints(time, budget, etc.)
• You try looking for tools which are particularly good at solving your specific problem and that integrate perfectly in your custom infrastructure. However, no such tools seem to exist or there's that little thing that you dislike.
• You then look for compromises and ways to solve the issues that won't get magically fixed by the tools.
• You don't have time to look at all the existing tools and evaluate them. You'll be selecting few tools and trying them out. Hopefully software vendors will cover the tiniest details which are relevant to your business needs, in their documentation.
• You decide and you live with it, maybe reevaluate your decision and revise your goals, but you move forward unless you really believe that you're wrong.
  

It's not easy to decide in the IT world. You might get it right or wrong but you may have the power to correct your mistakes. Whatever the choice, the rational move is trying to select wisely, going forward and take responsibility.

Playing with OSGI and JPA

I've been writing an IRC bot for fun, but it's far from being done. My goal is to experiment with JPA in an OSGI environment.

At work, I am using Hibernate, XDoclet to generate the XML and JPA isn't coming soon :-). My last JPA application was a pastebin application, with Wicket, hibernate search, Lucene, etc.

I'm using a friend's library Jerklib with Dynamic JPA. I'm still having some minor issues when deploying but I'll probably find a solution soon.

About the application

Environment

I have a multi-project with Maven and I'm using the maven bundle plugin and I'm developing in Eclipse 3.5 on Debian testing.

I'm using openjpa , dynamic jpa and couple of other dependencies

Design overview

a) Commands implemented as plugins : The bot has a set of factoids(learn, forget, etc...). Each command gets created using a factory.

// message listener //String operation = getOperation();

CommandFactory factory = ServiceFromOSGI.getCommandFactory(operation);

// if the factory is not null, redundancy for the operation parameter

// as a factory can have multiple commands

Command command = factory.createCommand(operation);

ircChannel.say(command.render(ircMessageContext));

b) The command service listens for removal or installation of commands and updates itself.

After writing couple of "users' commands", I would need to implement some administration commands(load/unload plugins, irc specific tasks, etc.).

Problems

The dynamic discovery is failing for now, the persistence provider class is not resolved, it might just be a bundling problem for openjpa. I wrapped it myself.

Conclusion

It's strange that many open source projects still don't provide an OSGI manifest. The maven-bundle plugin is very trivial to use for maven enabled project and there's still bnd.

While OSGI is an interesting technology, I personally don't know anybody using it in the enterprise unless they are an Eclipse shop. I think that it's mostly due to

• the lack of "OSGI enabled jars"
• the fear that OSGI might introduce unnecessary complexity
• the lack of step by step complete examples(if possible with screencasts)

There's plenty of documentation about OSGI and lots of successful applications(Web, Desktop) using OSGI. Hopefully my bot will be one those applications :-)

Sun acquisition by Oracle

I thought that Sun would be acquired by IBM two years ago or maybe earlier but I never imagine Oracle as a potential buyer. People seem to be concerned about the future of Java but I believe that any company would do better than Sun Microsystems in terms of management, vision, strategy and business model.

J2EE

Oracle acquired BEA last year and got WebLogic and JRockit JVM among other products. WebLogic seems to be the most respected application server right now, many big companies are running it. Medium to small companies tend to use JBoss most of the time. Some Glassfish v3 features could be incorporated into WebLogic. Why would Oracle invest into Glassfish? I don't see any compelling reason.

NetBeans IDE

My only concern is about NetBeans. I have no interest for Eclipse and JDeveloper. JDeveloper is a decent IDE for Oracle products. It looks very good for J2EE development and Oracle Centric stuff. I don't find the product very usable in general for anything else but J2EE (text editor, usability, plugins, etc.). I tried the IDE couple of times for the last 3 years and always went back to NetBeans. I suppose that Oracle will be merging interesting JDeveloper features into Netbeans instead of the opposite.

Oracle and MySQL

Oracle will probably incorporate whatever features they think are worth into their database and let MySQL be handled by the community. After some time, MySQL will rest in peace.

Java on the desktop

Will Oracle kill JavaFX? Right now, I don't see what's worth in JavaFX. Yes, next generation of applications, declarative programming, etc. Yes, they might be able to fix some design mistakes and bugs that they can't or don't want to fix in Swing. There are no official JavaFX binaries for Linux, Solaris, FreeBSD. Still those demos about circles, balloons and such. I don't see JavaFX as a competitor of Flash or Silverlight at the moment, it's way too immature right now. If the JWebPane component was ready, JavaFX would've gotten more interest, that's for sure. People would be like ok, we don't mind wrapping some swing widgets in JavaFX most of the time and now we've got a true web browser component.

Unix

IBM has AIX and Oracle will get Solaris. Sun improved their marketing strategy. They revamped the website which was awful before 2003-2004 and starting to put the "Java" trademark everywhere especially where it doesn't belong. In Solaris, some applications appeared out of the cloud, "Sun Java Browser" aka Mozilla, "Sun Java desktop" aka Gnome, etc. Solaris is still used by some companies as a server but it is barely used as a Desktop OS. The package management seems to have improved in the latest builds, but a project like Nexenta OS , basically Debian on a Solaris kernel is more promising on the Desktop.

What about IBM?

I am wondering now how IBM fight Oracle with the Java technology. They already made a move in the database market with EnterpriseDB. They have a JVM, a desktop toolkit, they are strong with J2EE(Websphere) and they have a bunch of developers/consultants.

To summarize it, I think that the future of Java is in good hands with Oracle. It will be interesting to see the vision/marketing switch when Sun acquisition is complete.

Thoughts about JavaFX

JavaFX has the potential to become something interesting. While there are many articles written about JavaFX, I have yet to see a non trivial JavaFX application. When browsing Dzone articles, it almost looks like JavaFX is popular, while it's not.

There's no amazing UI control and I am not sure that I could code an entire JavaFX application without writing few java classes. I am not fond of applets and I haven't written any for years. JavaFX doesn't solve the "applet problem".

I don't know about any cellular phone which is officially supporting JavaFX. I am also not aware of any software vendor distributing desktop applications written with that technology.

In my opinion, JavaFX is not ready for production use. What motivated the release of JavaFX? Maybe they've been advertising it for too long and they had to release something. I'll give JavaFX probably one more year before attempting to use it.

serialVersionUID in Netbeans

Most of the time, I use Netbeans when I have the choice. What I don't like about Eclipse and is getting me worried time to time is when the IDE freezes for a long time when you're not really doing anything.

Last week, I needed to build a simple Java project (Maven based build), about 50 000 lines of code(from sloccount). The project contains one core project and few sub projects. Eclipse took about 30 minutes to import the project and set up the classpath. That performance was achieved under a Quad Core, 2 GB of RAM, which is amazing. I had only Eclipse, Firefox and a terminal opened. I tried with both q4e and m2eclipse plugins, same results, I could hear my CPU making lots of noise. I had time to start cooking, boil water for coffee and do some other things, before the IDE was ready to use.

One of many missing features in Netbeans is the ability to generate the serial version ID for a serializable class. With Eclipse, you get the warning all the time, and you can choose between:

• ignoring it
• adding the annotation @SuppressWarning("serial")
• generating the serial version id.

Available plugins for Netbeans
There are two plugins available for Netbeans, that I am aware of : UUIDGenerator and serialVersionUID generator. I only have success with UUIDGenerator (most of the time, I am running the latest development build under Linux and Windows and lately Mac OS Leopard).

Enabling Serialization warnings
Under Tools->Options->Editor->Hints->Standard Javac warnings, select Serialization. That way, you'll see a marker notifying you that you're missing the declaration of a serialVersionUID field.




Generate the serial version ID
You can generate the serialVersionUID using the shortcut Control-ALT-Z. You can copy the generated contents to the clipboard and paste it inside your class.

Merry Christmas

XPontus and VFSJFileChooser were released this evening. I wanted to release before Christmas! Still the same stress and anxiety before and after publishing a new version. Now, I need to start advertising in forums, etc.

The last few days, well more nights than days, have been mostly about testing XPontus installers, fixing bugs, reviewing as much code as I could.

Merry Christmas everybody and happy new year!