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An Interview with Marko Boger
CEO of Gentleware AG

Introduction

Objects by Design is pleased to bring our readers this interview with Dr. Marko Boger, CEO of Gentleware AG, the creators of Poseidon for UML. Gentleware recently released Poseidon for UML 2.0, which includes major breakthroughs in technology, including UML 2.0 Diagram Interchange and a modular, plugin architecture.

UML 2.0 XMI

SZ: Recently, Gentleware and several other companies proposed an extension to the UML XMI format to include graphical information. Called UML 2.0 Diagram Interchange, this extension would allow the exchange of UML models together with graphical diagrams via XMI. It also talks about the presentation of UML diagrams within a browser using SVG.

What is the current status of this work as a standard and as a component of Poseidon? Has the proposal been well accepted? Does the promise of SVG diagrams in a browser look good? Are tool vendors really interested in exchanging models that include diagram information, or does this take away their competitive advantage?

Marko Boger: Our proposal was accepted as an OMG standard in March 2003. All competing submissions withdrew their proposals and joined our submission team. Out of the four work packages of UML 2.0, this was the only one accepted with no opposing votes. All major vendors joined or supported our submission and the general feedback was very positive from all sides. So I would say that the proposal has been very well accepted and I do expect that a large number of vendors will implement it.

Gentleware is the first to bring a tool supporting this new extended XMI format to market. Poseidon for UML 2.0 already has this technology fully implemented. With a reference implementation in place (from the people who defined the standard), I expect that other companies will find it straightforward to implement correctly and to the full extent, and I believe that it will rise to the promise of seamless model interchange between different tools. Over time, I expect that no vendor will be able to ignore XMI with Diagram Interchange, or they will lose market share.

We have designed this XMI format very carefully to allow a simple transformation to SVG. Bringing UML diagrams to the browser as SVG graphics has a lot of merit. Most of all, SVG allows for interactions like zooming or linking, but we are only beginning to discover the new possibilities.

At the OMG, a standard is first "adopted", then goes through "finalization" and then becomes "available". The Diagram Interchange standard is currently in the finalization phase, in which smaller problems that occur during implementation, or conflicts with other parts of the UML standardization process, can be fixed. It will become an "available standard" in the first quarter of 2004. With Poseidon for UML 2.0, we are providing the very first implementation on the market.

MDA

SZ: Does Gentleware have any major initiatives underway for the OMG's Model Driven Architecture (MDA)? How much demand do you see in your customer base for MDA? What custom transformations are people asking for, if any? Would you say that MDA is more promise than reality at this time? Do you see the ArcStyler / MagicDraw alliance as a competitor?

Marko Boger: MDA is certainly an important topic. We at Gentleware are strong believers in model-centric development. In fact, we believe that we are facing a paradigm shift - from object-oriented software development to model-centric development. It might go smoother than the shift from procedural to object-oriented. But for many it will be just as hard. Model-centric development with UML certainly includes object-orientation, but it goes beyond. We will not only express static architectures, but also behavior and processes in models, as is currently done in some segments of the industry, embedded systems being one such example. UML 2.0 is well prepared for this and has the potential to bring this to mainstream software development. MDA is just the beginning of that.

We at Gentleware intend to play a leading role in the area of modeling and modeling tools. We will concentrate on making the modeling tool itself as usable and intuitive as possible. For model transformations we plan to establish strong alliances. ArcStyler is one of the tools we are looking to integrate and we are in close contact with the company behind it. We are also in very close contact with open source projects, AndroMDA for example. The integration with other tools or vendors is very smooth, since we probably have the nicest XMI output, as well as an open and JMI-compliant API for direct integration as a plugin.

ArgoUML

SZ: Poseidon originated from ArgoUML. How has the Poseidon relationship evolved with the ArgoUML project? Does Gentleware still contribute source code back to ArgoUML on a regular basis? Are there major areas of departure? How do you see this relationship continuing in the future?

Marko Boger: When I first got involved with ArgoUML it had four diagram types. For research purposes I needed just the other five! I was able to interest a whole group of people in this project and we committed ourselves to it. Instead of just adding the missing diagram types, we first completely rebuilt the architecture (for those who don't know, we put in NSUML and XMI support). Then we had a usable framework to add the missing diagram types. This, as well as the clean XMI support, made ArgoUML very popular. Only afterwards did the idea to start a company around ArgoUML arise.

But in other areas also, the architecture of ArgoUML proved to be too weak for a robust product. Today, the architecture of Poseidon is very different from that of ArgoUML. We did feed code back to the open source project for quite a while but it became unmaintainable. We are now using a different UML version, a different XMI version, a different repository, a different rendering engine and so on.

The open source project is still alive, but not really kicking. It needs more people that can devote serious free time to it. More students or research groups would do the project well. I think it would be great for the entire industry if it continued.

Plugins

SZ: What are the most popular plugin's for Poseidon? What are people asking for and what has Gentleware planned for future plugins? Is the plugin architecture working from a sales and marketing perspective or do you see folding more of the plugins into a consolidated, high-end product in the future?

Marko Boger: The plugin API is actually very successful. We have a couple of companies building either plugins for internal use or preparing public products. In fact, we make heavy use of the API ourselves. That makes Poseidon very modular. For example, every diagram type is a module in its own right.

The most popular plugin is certainly UMLdoc. It creates documentation from UML models in a way similar to Javadoc, but includes much more information, like diagrams, use cases, processes, etc. We continue to put a lot of effort into this plugin. Support for SVG will soon go into UMLdoc.

Another great plugin for Poseidon 2.0 is the UML-Autolayout Plug-In. This was developed together with a partner company that specializes in graphing algorithms. It produces very nicely laid out diagrams for reverse engineered classes or hand developed diagrams. Layouting for UML is a very complex topic and this solution takes a lot of its elegance from our new UML 2.0 Diagram Interchange implementation.

Future of Poseidon

SZ: Recently you announced a round of outside investment in Gentleware and Poseidon. We are looking forward to and anticipate advances in the product as a result of this investment. Could you give us a preview into the future of Poseidon? What exciting features are planned?

Marko Boger: Indeed, we have closed an investment round recently and have since then almost doubled our development team. But there is actually yet another reason why you can expect great new features in the near future. Next to having more people, we have reached a technical level with our internal frameworks that allow us to develop new features much more quickly. You can expect support for a number of languages soon. With the release of Poseidon 2.0, we will support Java, Corba IDL, C# and VB.net. More languages will follow.

UML 2.0 support is another big feature planned. We are already supporting the UML 2.0 XMI format and expect to be one of the first to fully support UML 2.0. We are also working on integrations with IDEs and MDA tools. We will continue to put a strong emphasis on usability and productivity. There is a lot to come, so stay tuned.