This day started with a keynote by Roy T. Fielding, talking about his work on RESTful APIs. Was quite interesting to hear how the work on his PhD thesis evolved into a widely used principle of interacting with resources in the web – and how unwelcome it has been to certain people. However, if someone did not have and idea about Representational State Transfer, I don’t think that he would have found out on that occasion. Later on, Philipp H. Oser of Elca had an entertaining talk on fighting the heterogenity when working with Java frameworks. Besides of – not meant to be serious – ideas of Sun acting as MS-like dictator or someone implementing an Uberframework (10% better than the rest), he explained the two most promising approaches. One being the Spring way: the usage of a dependency injection framework that allows developers to interconnect various frameworks in a common manner. The other approach would follow the principle of LAMP: bundling the most commonly used frameworks and adding some extensions, easy installation and template applications to it. And what technology would you use for weaving the parts of this bundle? Of course a dependency injection framework.

Interestingly, the Apache Geronimo server runtime framework seems to be heading the same way. What would you do if you have a collection of widely accepted frameworks, each of them carried by it’s own community and each of them implementing a part of the Java Enterprise specification? How would you react to the market share of JBoss and Sun’s Glassfish initiative? Fortunately the people at Apache did not decide to hardwire their frameworks to a monolithic server (and therefore killing their drive and innovation) or – even worse – to build a new one from scratch. Instead they started to build a “server runtime framework”, which allows the bundling of the best parts of their projects (leaving the decision up to you, which ones you consider to be the best) under common administration and management. It will be interesting to see, how soon software from other implementors will be “GBeaned”.

Other talk covered an introduction to the Semantic Web for Java developers. By the way, the Java technology was of no importance here. Dean Allemang of TopQuadrant was talking about several standards for creating semantics, and about how he uses these for homogenize various data sources he wants to mash-up. The destination form is always RDF, no matter whether the metadata was originally provided in the form of microformats, RSS, Atom, spreadsheets, relational databases or anything else. Transformations (e.g. XSLT with the help of GRDDL for microformats) convert the feeds to RDF, these feeds are then interlinked by using OWL.

Since this day was really stacked with presentations, I could get some information about today’s initiatives on SOA (webservices by annotation, BPEL and the JBoss ESB), the current state of the Java API for RESTful Webservices JAX-RS, the possibility to use evil-evals by instanciating a JavaScript engine (or other script engines) inside the JVM and, last but not least, a promising project of the Zürcher Hochschule Winterthur ZHW for generating DDL and PoJos with Hibernate annotations out of Entity-Relationship-Models. And David Nüscheler, CTO of Day and lead of the Java Content Repository specification, introduced r-jax (acronym for “Repository backed aJAX”), a simplified and easy-to-use view on a JCR. As a proof of efficency he transformed Stefano’s Linotype blog (one of two blogs he admitted to read) into a JCR based weblog within only 15 minutes.

Two keynotes and seven presentations today – quite some information that is piling up – and that’s only one day of four. That intensifies the impression I had yesterday already, that to my opinion it would have been better to have fewer presentations and more time for each one of them. The most interesting speeches had to stop exactly at the time where you would have been able to dig in deep instead of just scratching the surface.

The future of Java seems to be about support of various programming language. Is this not paradox? Isn’t Java exactly one programming language? The situation reminds of the Bible’s story about the Tower of Babel, built by humans in order to reach a state equal to God. Following to this they got punished by speaking different languages, unable to communicate with each other again.

The use of several programming languages does not necessarily need to be a punishment for developers. Java’s attempts to compete on the presentation layer of web applications by technologies and frameworks such as JSPs, Java Server Faces, Struts, Spring MVC and various others never allowed an efficiency comparable to Jython, JRuby or Groovy. And in addition, Java is more than a programming language. At first place, the core of the technology stack is the virtual machine, allowing to run bytecode on any platform that has a Java Virtual Machine developed for it. That you could write Java bytecode compilers for any other language is obvious. And not that the Java platform is to be open sourced, everyone will be free to dig in deep and start working on that.

Today’s keynote and two of the speeches I attended touched this subject. I am very excited about the fact, that the support of some languages (e.g. JRuby, Jython) will be targeted for Java SE 7. Well – besides of the Visual Studio’s ease of use, the openness to several programming languages was maybe the only reason that made us Java developers watching our .NET colleagues full of envy. Unfortunately, I did not find any answers to my main questions today. If the Java programming language can coexist with more dynamic – in some cases more efficient – programming languages: which ones would you choose? How would an ideal multi tier software architecture be mapped to those languages? How does the interoperability look in the real case? And – even if development could take less time – how could you assure that a large project stays maintainable when the complexity of speaking several language arises beneath the complexities that the project causes itself?

Even though I know that certain programming languages are better suited for certain tasks than others I am not a very big fan of a complete freedom of choice within a project. Clear separation of concerns is still needed. In our project, we started using Jython to support the pure Java development. But we try to use it really “only” as a scripting language, which allows us to job control in import, export, aggregation and maintenance tools. The main business functionality is still written in Java. In the future, the advantages of other languages will possibly only count if the whole platform stays homogeneous and maintainable. Otherwise the parable of the Tower of Babel will be applied once again.

But let’s not talk to bad. I am really looking forward to the Dynamically Typed Language Support. Besides of that, the new Java Standard Edition will bring a lot of other exciting features. The ones I am already nervous about:

• Selective export of classes (how is it at your place? Is everyone in your house your friend?)
• Java Module System (“superJARs” making packaging easier)
• JSR 203 NIO.2 (extending non-blocking io)

If you want to know more about this, have a look at Danny Coward’s blog. He is supposed to know which features are going to make the cut.

Of course there have been other interesting topics as well. For example I was impressed by the possibilities that Open ESB will bring to all those who face the challenge of building homogeneous applications in a heterogeneous environment. Not only that a lot of Binding Components are implemented for communicating with external systems and technologies, the monitoring capabilities and the IDE integration (even though currently limited to NetBeans) look promising as well. And a speech about JPOX and spatial extensions covered mechanisms for persisting spatial data. The most helpful pointer of this lecture was however not JPOX itself but the supported Java Topology Suite JTS, which offers a large set of operations on spatial data types. I’m surely going to have a look deeper look at this framework, hoping that it will provide means to geographical search to more complex area shapes than just rectangles and circles.

Not If you take the large developer conferences as an indicator. While JavaOne already took place in San Francisco earlier this year, Antwerp in Belgium will host JavaPolis and the various JAX conferences will be held in Munich, Singapore, Jakarta (where else would you expect a Java conference?), Wiesbaden and Bangalore.

Switzerland is left out there. Well – it was until this year. Beginning from next Monday we will have our own Java Developers Conference: Jazoon ‘07. It is branded as “the international conference on Java™ technology”, revealing the plans of the organizers to establish an event with – at least – European reputation. However, you could not expect them to reach this goal already in the first year. Most of the speakers are earning their money in Switzerland, with the sponsors it’s the same. Audience however is expected from 28 different countries, still most of them being Swiss. This does not tell anything bad about the conference itself but there are still some miles to go on the road to international relevance. Anyway, they managed to acquire some high-class people for the keynotes, such as Roy T. Fielding and Erich Gamma.

The location seems to be ideal for starting a new thing since it is brand new as well: Sihlcity in Zurich. I’ve never been there so far, so I’m quite excited.

Speaking about the topics. There will be enough interesting speeches to make me happy – it won’t get easy to decide for the right ones. When the talks about frontend related things and J2EE will not attract me the most (not that I would not be generally interested – it’s more about the fact that my current work has different requirements), there are still some things I don’t want to miss:

• (560) What’s wrong with Java? A look over the horizon.
• (561) JPOX-Spatial – Extending JPOX with Geospatial Data Types
• (582) Java and Scripting: One VM, Many Languages
• (870) Semantic Mash-ups using RDF, RSS and Microformats
• (880) Parallel Computing Scenarios and the new challenges for the Software Architect
• (1920) JAX-RS: Java API for RESTful Web Services
• and many more

As I will spend there the whole week, I hope to learn a lot of stuff that’s worth writing about.