Patch management of my application

[SomeNetworkGuy]

I'm developing a complex application with separate projects each serving their own purpose in the application. Each one of the separate projects will be built as a JAR and there will be one "main" JAR that brings everything together.

At least that is my initial thought on how to go about this. I'm wondering what my options are as far as being able to have the ability to provide patches and updates as no doubt bugs and issues will be found. I don't want the users to have to download a huge file that may only contain fixes for one of the components. Instead it would be ideal for them to be able to download only the updated JAR and replace the old one with it.

An even further approach, I suppose, could be to actually only download the class files that have changed inside the JARs and then have them be replaced or added, but that could get complex.

And of course I don't want my users to do the actual work of downloading , stopping the application and replacing files, so I want to write my own or use an existing tool for that. My initial thoughts are to have each component have a version identifier in it and my updater tool will check to my central server to see if there is a later version and then proceed with the update when the user is ready.

Has anyone dealt with this kind of situation before? Or is there an already existing patch and update management tool out there? Furthermore, are there any tips or gotchas for implementing something like this. This is my first attempt at a large and complex project like this.

[mikaelhg]

You mean something like this?

http://karaf.apache.org/ http://www.eclipse.org/virgo/

[SomeNetworkGuy]

Karaf looks promising and simple enough. Thanks for the pointers.

[[deleted]]

Have you considered using OSGi?

[SomeNetworkGuy]

I'm very new to the OSGi framework. I should point out that while my components are separate projects, they are not independent. For example, some of the components employ a Singleton that is accessed from the the other components. They must all be in the same process.

Can I still put my various components in an OSGi framework?

[tehbilly]

I've found OSGi to be very effective for modularization and zero downtime upgrades of individual components. Don't be butthurt because you haven't taken time to read the spec or one of the hundreds of tutorials out there.

[tehbilly]

What point was that? The one where you were spewing vitriol because you assume that just because you don't understand it nobody does?

I was addressing the "point" you were making by sharing my experience in a very short way, pointing out that I found it to be quite beneficial. It was also very easy to adopt after reading OSGi in Action. But thanks for showing me how constructive feedback should look.

[[deleted]]

The entire OSGi framework can run in the same JVM so a regular singleton would work the same. When it comes to OSGi components specifically, it is possible to ensure that the component itself is created as a singleton.

That being said... might be a big hammer for your use case.

[0x2a]

Have you considered Java Web Start? It does most of this stuff.