Al Blue: “Module versioning is like playing the piano. The problem isn’t how many digits you’ve got, it’s using them effectively.“

Nice insight on version numbering in  JSR 277 and OSGi. (Via Steve.)

Last week at ApacheCon EU I made a case for content repositories as a general solution for applications that are currently forced to fragment their storage needs due to the different limitations of traditional storage methods, mostly file systems and databases plus more recently cloud services on the network. See below for the presentation:

It seems like the message was well received, after the presentation I got a lot of positive feedback from people who had previously thought of content repositories as something you’d only use for storing content in a content management system. Instead I see a content repository as a unifying storage layer that can be used for almost anything ranging from traditional content and data to configuration files, user account information, preferences, templates and scripts, source code and binaries, ad-hoc annotations, etc.

Interested in JCR and looking for a new laptop? My employer has announced JCR Cup 2008,  a JCR design and development competition. Too bad I can’t enter the competition, I’m sure we’ll come up with a whole load of cool ideas next week.

Like many others, next week I’ll be in Amsterdam attending ApacheCon EU. This is my fourth ApacheCon, and it seems like every time I get myself involved with more stuff to do and more people to meet. I’m still trying to piece together my schedule for the week, but here’s what I’ll be doing already on Monday and Tuesday.

Monday: Media training, BarCode

On Monday I’ll be attending Sally Khudairi’s Media & Analyst Training and Intermediate Media & Analyst Training classes to improve my media skills and knowledge. I attended the first class already once during ApacheCon US 2006 in Austin, and found it very interesting and useful. Now I’m hoping to rehash the things I learned earlier and learn something new during the second class in the afternoon. It’s really cool and very useful to have something like this as a part of the conference.

The downside of attending the classes is that I miss much of the Hackathon action during Monday. But luckily there’s the BarCode event where (if not sooner) I hope to catch up with Day people and other fellow hackers. The conference networking site has already helped me hook up with some new people I’d like to meet.

Tuesday: JCR meetup, WebDAV, hacking, dinner

Tuesday is the first big JCR day of the week. The JCR meetup starts at 9am and continues to 1pm with lots of cool topics and attendees. The event is free for everyone and takes place right next to the ApacheCon venue, so feel free to drop by if you’re around and interested in JCR and related technologies!

I’m especially looking forward to the JCR content modeling workshop that we’ll likely organize at the end of the meetup. Besides ideas and questions from existing JCR users, I’ve invited other Apache projects like Abdera, James, JSPWiki, Lenya, and Roller to participate if they’re interested in evaluating how a JCR content repository could best support their content models.

After the JCR meetup I was thinking of perhaps putting up a short informal WebDAV library BOF with anyone interested who’s around. There’s a long-standing need for a good WebDAV protocol library but with Slide gone, there currently is no clear development community that could adopt the various pieces of WebDAV code in different Apache projects. It would be cool if there were enough interest for example to bootstrap a new incubating WebDAV project.

If I have time (and energy!) beyond those activities on Tuesday afternoon, you’ll probably find me in the Hackathon working on some prototype integrations like the ones we’ve done in previous Hackathons. Ping me if you’re interested in hooking some code up especially with Jackrabbit or Tika!

There’s an initial plan of having a dinner with other JCR people on Tuesday evening. Let me know if you’re interested in joining us.

Congratulations to the eXo team for releasing eXo JCR 1.8!

It’s cool to see the various JCR implementations evolve and grow. The JCR 1.0 standard is  less than three years old, and there are already a number of independent implementations, both open source and commercial.

So far we’ve seen little cooperation (apart from JSR 283) or even much direct competition across the implementations, as I guess everyone is just busy grabbing market-share from pre-JCR vendors. But I wouldn’t be surprised if we started seeing more benchmarks and feature comparisons on JCR repositories already during this year. I expect it to be fun!

I just announced the release of Apache Jackrabbit 1.4. The release is the result of about nine months of development since the 1.3 release, and contains 220 new features, improvements, and bug fixes (plus the 75 bug fixes that had already been backported to 1.3.x patch releases). This is by far the biggest Jackrabbit release to date.

The 1.4 release contains some cool new features:

• Friendlier Jackrabbit webapp. The jackrabbit-webapp component now comes with a more polished user interface, better error handling, and improved repository connectivity for local and remote clients.
• Object/content mapping framework. The jackrabbit-ocm component maps Java objects to JCR nodes and vice versa, making it possible to persist normal Java objects in a content repository.
• Service provider interface for JCR. The jackrabbit-spi component defines an architectural layer below the JCR API. The SPI layer is designed specifically for remote access and outlines a way for us to avoid the performance limitations of JCR-RMI that works on top of JCR.
• Optimized storage for binary content. The new DataStore feature in jackrabbit-core avoids all unnecessary copying of binary content and promises huge performance increases for versioning and copying operations. DataStore is a beta-level feature in Jackrabbit 1.4 and disabled by default.
• Improved query engine. The jackrabbit-core component has been extended with new features like configurable indexing, synonym and similarity queries, and spell checking. Many typical queries are now noticeably faster than before thanks to numerous performance improvements.

Many thanks to the Jackrabbit development team and the entire community! I’m really proud and excited to be a member of the Apache Jackrabbit project.

PS. Interestingly enough, I built the final 1.4 release candidate exactly two years after I first volunteered to be the release manager for Apache Jackrabbit. The past two years have certainly been interesting time.

Yesterday, during the Fast Feather Track at the ApacheCon US, I presented the incubating Apache Tika project. See below for the slides:

I was positively surprised about the level of attendance and also the interest in Tika during the Search Roundtable BOF later in the evening. Even though the project is still just starting, it’s already generating lots of interest and I really look forward to getting the first releases out.

There’s an emerging cluster of digital media projects at the Apache Software Foundation. The Tika and Sanselan projects are currently incubating, and PDFBox is likely to soon follow the example. Together with existing projects like Batik, FOP, POI and the many HTML generators at Apache they form a nice set of tools for consuming, manipulating, and producing various types of digital media.

It would be nice to see also some audio or video processing software entering the ASF…

The heavy concentration of Apache developers here at the ApacheCon US in Atlanta got me thinking about how the various Apache projects are related and whether we could come up with some ways to visualize the existing (and emerging) community patterns.

As a quick first step I just took the committer lists of all Apache projects (excluding meta-projects like Jakarta or Incubator) and ran it through an ad-hoc Perl script that identified any pairs of projects that have five or more committers in common. Running those relationships through Graphviz produced the following diagram:

Interesting stuff… Of course the committer lists are not a very accurate source of information as many committers are no longer active in the projects they once contributed to, so I perhaps should be looking at svn commit logs instead, but as a first approximation the above diagram is already quite nice.

If you’re interested in concurrency, distributed systems, and ways to best use the manycore processors we’re being promised, then check out the Concurrency and River thread on the development mailing list of the incubating Apache River project. The thread is about concurrency and ways the River project (a continuation of Jini from Sun) and related technologies like JavaSpaces could be used to parallellize many computing tasks. There are also some nice comparisons to Erlang and Scala, and how the actor model used by them is related to the Jini network model.