TechJava

Yesterday, the OSGi session took place in Hotel East in Hamburg. Peter Kriens, the OSGi evangelist showed a wonderful Zen Presentation on OSGi. I wrote a lot during his talk which happens to me very seldom. Here are the core statements I understood:

• The core difference between usual plugin architectures and OSGi is that OSGi concentrates on collaboration of the components.
• OSGi delivers a controlled environment, in which the question if a component runs or not can be answered in beforehand.
• OSGi bundles use metadata (about versions, dependencies, etc) to predict an error, not discover it in runtime.
• OSGi has a very narrow API containing the minimal common part.
• OSGi consists of module, life cycle and services layers. The initially developed services layer required smart class loading mechanisms (module layer).

1. The module layer is desigend to control the class loading machanisms (e.G. structureal class loader hierarchies instead of a linear classpath)
2. Life cycle layer adds a management API (e.G. inform the others about installation event)
3. Separation of concerns is promoted by definition of services for different tasks.

• Services are used for decoupling of system parts (This is a standard application of service-orientation).
• OSGI makes dependencies explicit (private, import, export)
• OSGI tries to make the system managable, taking dynamics and lifecycle as fisrst-class citizens
• OSGI will be extended to support distribution: the team works on policies, SLAs, etc…

I liked the talk and the way how Peter Kriens addressed the problems of OO. I was confirmed in some ideas about coupling that will be layed out in my thesis. After the presentation we had a delicious meal and wraped up the evening with interesting discussion about pros and contras of OSGi. Peter Friese showed me some remote OSGi staff, he was playing with. The lack of documentation in this area makes it a little difficult, but I hope he will post some news on it. As usual, you can find other pictures in my FlickR gallery.

The organizers of the upcoming OSGI event selected a promiment Hamburg’s nightlife location. The location is a evidence of modern design. The entire hotel is equipped with non-standard items in various forms and colors and commemorates on Dali and Gaudi in the same time.

Topic: Why Modularity is Important

When: September 9th, 2008, 19:00 CET, Registration required

Where: East Hotel Hamburg, Simon-von-Utrecht-Strasse 31, 20359 Hamburg / Germany

Abstract: Many developers are finding out that modularity has a significant influence on the development process. But unfortunately, Java has no concept of modularity, all JARs are placed on a linear classpath. Many projects have developed in-house plugin frameworks to achieve some modularity. The OSGi Service Platform is a standards based framework used by many projects. Some of the best known projects that use OSGi are Spring and Eclipse. There are many open source projects and commercial companies that have implemented the specifications: Apache Felix, Knopflerfish, Eclipse Foundation, ProSyst, IBM, Siemens, Hitachi, Samsung, etc. This presentation will analyze the problems with (the lack of) Java modularity and explain how OSGi provides many benefits for the development process as well as make the applications itself easier to maintain and extend.

Author: Peter Kriens

The vacation time of most people is over, so it is time to meet and discuss a little. A good opportunity to do this will be given on September 1st in Roxie, Hamburg during the Eclipse Stammtisch. The event name translates into regular’s table and indicates a regularity of the happening. Even if the upcoming event is only the second in series I expect to meet many people after the great feedback after the last one.

Details:

• When: Monday, September 1st, 19:00 CET
• Where: Roxie, Hamburg, Germany
• Directions: http://www.roxie-hamburg.com/roxieway.htm
• Who’s comming: Doodle Poll

See you next Monday.

The Java User Group Hamburg (JUG-HH) organizes another event at Lehmanns Bookstore in Hamburg. This time the subject of the talk is build management and project automation with help of an open-source tool called Maven. Maven is a software project management and comprehension tool. Based on the concept of a project object model (POM), Maven can manage a project’s build, reporting and documentation from a central piece of information.

Yesterday, as reported earlier a great session on Java EE 5 featured by Adam Bien took place in Lehmanns Buchhandlung in Hamburg. It was a full success, having approx. 100 developers taking part. Adam asked for the experiences with Java EE and it seemed to be a bunch of professionals. The session slides contained only headings, the rest of the story has been done in NetBeans 6.1 and Glassfish. The entire session has been executed on pretty high speed – to be honest, Adam spoke that quick I just could understand. The session took place in the bookstore, that basically sells two types of books: computer and medical. Adam noticed that the shelf to the right of him contained books on psychiatry, and pointed each time he wanted to express that the antipattern leads to…

Regarding the content, Adam focused on two main directions: the basic enterprise patterns and enterprise anti-patterns (this could be a good book title, btw.). General ideas, like support of DRY principle, convention over configuration and IoC, that are on my opinion the greatest achievements of Java EE 5 has been explained in a very plastic way. Especially, Adam really showed, that the bad-artifacts that made J2EE development boring disappeared in Java EE (or may be better to say: can be avoided). The last part of the talk was attended to the nonfunctional activities around the developed software. Adam focused on testing, management, monitoring, performance, etc… It was pretty interesting to see that Java EE community listens to the developer voices and push the technology towards modern, pragmatic and efficient programming platform.

During and after the session one could ask questions around the topics. Adam told a lot during the answers and proved again his excellent expertise in the Java in general and Java EE in particular. I really enjoyed the session and hope that the next one will not let us wait for several years again. Adam spoke about possible JavaFX session – this would be also very interesting.

( more photos in my photostream)

As announced in a previous post, Egon Boerger introduced his current work on Semantical Model of BPMN. The computer scientist, known by most of us through his work on Abstract Sate Machines (ASM), focused in his talk on the try to improve the BPMN with a unambigious and clear meaning. Especially, he showed in a very plastic way, how a formal specification can foster the understanding of a standard like BPMN. In doing so he reveal several weak points of BPMN concerning the meaning of splits/merges. Especially, those become a real problem if you use BPMN like a workflow language.

The main message of Egon was the need of formal specification and separation of specification from implementation. He showed how this can help in order to define the semantics. I was glad, that he confirmed some statements I’m discussing in my thesis.

Another positive message was that he is in touch with the OMG and SAP guys and his propositions are not only know in academia, but also in the standardization organization like OMG. He reported about some positive feedback from them, and spoke about some contributions to the BPMN 2.0.

I really enjoyed the session, because I like this old-school-style computer scientists. They spread their meta-thinking of a very high level and precision, that sometimes drives us progmatic guyes crazy. In the same time, they establish a natural meaning of quality and foster the reasoning about the topic, we are dealing with everyday…

( more photos in my photo stream)

May 19th, 2008 seems to become an important day for the computer science in Hamburg.

Modelling BPEL Using Abstract State Machines

May 19th, 15:30 – 16:30
Ditze Hörsaal, Schwarzenbergstr. 95, 016 (AudiMax I building), 21073 Hamburg
by Prof. Egon Börger from the University of Pisa, Italy. ( original announcement)

It starts with an invited talk of a Prof. Dr. Egon Börger, famous computer science researcher, applying the concepts of Abstract State Mashines to the software and hardware design at Hamburg University of Technology.

Pragmatic Java EE 5 Hacking – Rethinking Best Practices

May 19th, 20:00 – 22:00
Lehmanns Fachbuchhandlung (am Hauptbahnhof)
Kurze Mühren 6, 20095 Hamburg
by Adam Bien ( original announcement)

On the same day the meeting of the Java User Group Hamburg takes place at Lehmanns Fachbuchhandlung. This time an invited talk on “Progmatic Java EE 5 Hacking” by Adam Bien. Java Champion Adam Bien is a self-employed consultant, lecturer, software architect, developer, and author in the enterprise Java sector in Germany who implements Java technology on a large scale. He is also the author of several books and articles on Java and J2EE technology, as well as distributed Java programming. His books include J2EE Patterns, J2EE HotSpots, Java EE 5 Architectures, Enterprise Architectures, Enterprise Java Frameworks, SOA Expert Knowledge, and Struts, all published in German.

Java EE 5 is a revolution, not an evolution. Perhaps it goes not far enough – however some best-practices and patterns need to be pimped up, re-thought or pruned. After a short introduction into Java EE 5 / Java EE 6 (with a from scratch creation of a simple application with all “enterprise features”). The talk will provide the concept, patterns, best practices and discuss the context, advantages as well as shortcomings and provide suggestions / solutions for Java EE 5/6. This session will be interactive / openspace like. I’m really open for constructive criticism and will try to answer all questions with …code and real world context. Some upcoming Java EE 6 features will be presented as well.

So, see you there…