> Archive > Issue XLIII: September 2010 > SOA Pioneers Interiew Series: Art Ligthart, Volker Stiehl, and Stefan Tilkov
Amy Chou

Amy Chou


Amy Chou is a freelance Communications Editor. She has managed various publications, including issues of the SOA Magazine, and has overseen social-media platforms for the SOA and Cloud Symposium event series. As an IT journalist, Amy develops and maintains podcasts for which she conducts interviews and engineers the recordings. Amy is further responsible for various Web and marketing design initiatives and acts as a liaison between marketing and technology research groups.


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Ir. Art Ligthart

Ir. Art Ligthart


Ir. Art Ligthart works as a Principal Solution Architect in the SOA Consulting Group of Ordina, a large IT services provider in The Netherlands. He specialises in Service Oriented Architecture and modern application integration technology. His main drive is to use SOA as an enabler in solutions for business process improvement and enhanced business agility. He has published several articles and books on application architecture, including a book with best practices for the successful implementation of SOA ("SOA. Een praktische leidraad voor invoering: Socrates™", SDU 2005).

Art holds an MSc in Information Technoloy and Management from the University of Twente. He can be reached at or


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Volker Stiehl

Volker Stiehl


Volker Stiehl studied computer science at the Friedrich-Alexander-University of Erlangen-Nurnberg and joined SAP in 2004. He is on the solution management team for a development toolset for applications built on top of an SOA landscape (composite applications). He is also responsible for methodologies and best practices in composite application development. Volker holds workshops in composite applications and is a regular speaker at various conferences, such as SAPPHIRE, SAP TechEd, Jax, and JavaOne. Before joining SAP, he spent 12 years with Siemens as a consultant for distributed J2EE-based business solutions and integration architectures based on various technologies. You may reach him at


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Stefan Tilkov

Stefan Tilkov


Stefan Tilkov is co-founder and a principal consultant at innoQ, a consulting firm with offices in Germany and Switzerland. Stefan focuses on enterprise architecture consulting for Fortune 1000 companies, which currently translates to assessing SOA maturity and deriving appropriate steps for a road map towards a service-oriented enterprise. Stefan has been involved in the design of large-scale, distributed systems for more than 15 years, using a variety of technologies and tools ranging from C/C++ and CORBA over J2EE/Java EE and Web Services to REST and Ruby on Rails. In his current work, he is actively participating in SOA projects using both RESTful HTTP as well as the WS-* universe. Stefan is the author of "REST und HTTP" and co-edited the German SOA book "SOA Expertenwissen", has written numerous articles on SOA, Web services and REST and is a frequent speaker at conferences around the world. He is a member of the SOA Manifesto Working Group, the JAX-RS (JSR 311) expert group, and headed InfoQ's SOA queue for several years.


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SOA Pioneers Interiew Series: Art Ligthart, Volker Stiehl, and Stefan Tilkov
by Amy Chou

Published: September 15, 2010 • SOA Magazine Issue XLIII

The new podcast series from the International SOA & Cloud Symposium features interviews with some of the SOA Magazine's very own contributors. These exclusive interviews will be posted daily throughout the month of September until the start of the SOA & Cloud Symposium and can be found at the SOA & Cloud Symposium home page. The podcast will feature speakers, keynotes, panellists, authors, and industry professionals. Tran scripted versions of the published podcasts have been generously shared with the SOA Magazine by the SOA & Cloud Symposium. The interviews feature: Art Ligthart from Ordina, Volker Stiehl from SAP AG, and Stefan Tilkov from innoQ. These interviews explore the featured experts current and past projects, perspectives on the industry, involvement in the SOA & Cloud Symposium, and more.

Exclusive Interview with Art Ligthart

Art describes his experience being conference chair and the evolution of the SOA & Cloud Symposium. The discussion delves into Art's role as a partner at Ordina, his work as a principle consultant and his upcoming books and projects. Art also talks about the conception of the SOA Manifesto, the maturity of SOA, best practices, and more. Tune in to get the latest from Art himself.

SOA Magazine: Hi Art, how are you today?

Art Ligthart: I'm fine. It's a pleasure to speak with you.

SOA Magazine: As the conference chair of the previous two symposiums and as the chairman again this year, how do you think the event has evolved so far?

Art Ligthart: Interesting question. This is the 3rd edition we are doing. I think the first time we were already spot on. From the 1st moment we went to the phone with Thomas Erl. We had an agreement that it should be a very content driven symposium; no marketing talks, no vendor talks, just pure content. So it was the kind of symposium, specifically for the SOA community where experts could share best practices and knowledge.

I think right from the start, everyone wanted to participate from the speaker's role, it was very exciting. Since it was a content-driven symposium, we selected the speakers based on the fact that they had to be experts - so all of the speakers were publishing articles or books on the subject. As a result, I think both speakers and participants at the 1st symposium were equally excited about the conference. The 2nd symposium was similar in that way, we also decided to add a Cloud Symposium part.

It's a platform for the community. So you could say the 1st edition was spot on, it didn't evolve on the content so much as on the fact that we were now sharing knowledge among the top experts in the world, and I think that the experts and participants enjoy coming back each year.

SOA Magazine: What has your experience been like with being the central figure within past events and the current one?

Art Ligthart: I don't consider myself much like the central figure. I am proud that we were able to create such a platform, where everybody enjoys coming and sharing their knowledge. I think the central figure would be more like Thomas Erl, but at the same time it's also the whole community of experts. We are proud that we organized this. It├Ęs fun, the fact that everybody keeps on coming back gives us more so the pleasure. I don't consider myself a central figure; I'm enjoying this as much as everybody else.

SOA Magazine: I read your profile on the SOA & Cloud Symposium and noticed you have written a few books in what looks to be German. Could you tell me more about these books?

Art Ligthart: These books aren't in German, but in Dutch, which is a similar language to the International community but different to us. What we did - we started our first project using Services in 1999 - 2000. A couple of years later, we start to collect best practices on the subject from how to do this project, how to use patterns in the architecture. Our first book was in 2005 on the subject of SOA. Three years later, we published the second one. It's much more like a collection of best practices - Dos and Don'ts. Most recently, we started to write another book on the latest projects we did, combining services and rules.

SOA Magazine: Are you currently writing any upcoming books and could you tell us a little bit more about those?

Art Ligthart: We've been involved with a project for the last two years - a big project in the Dutch government, for Immigration and Naturalization Services. What we did there was used some standard software, we used some Oracle Web middle products and CRM applications. What we did is that we implemented the rule engine & modeled as much law and regulations as much as possible to form rules. These rules and rule engines can be called services. We call them Knowledge Services. In a way, we are mixing the Rule Oriented Architecture with Service Oriented Architecture and the whole system is very agile, the whole core of it is event-driven. So you could say we mixed three architectural styles into one application which was quite innovative, which is one of the things I am going to talk about at the Symposium.

SOA Magazine: I also noticed that you are a partner with Ordina, could you tell us about your role there and what Ordina is doing today?

Art Ligthart: Ordina is one of the larger IT Services Provider in the Netherlands. We consider ourselves the smallest of the big firms. We especially focus on the Dutch and Belgium market. We're proud to be innovative with architecture; the project I just mentioned is just one example. I'm a partner with Ordina and it's not a managerial role but more of principle consultant role, someone who really specializes in a certain subject and my subject is IT architecture. So that's why from this role, I got involved in the SOA Symposium in the first place. It's a way to facilitate and to join the community on IT architecture, especially service-oriented architecture.

SOA Magazine: I watched the video for the announcement of the SOA-Manifesto from last year's symposium where you spoke (listeners, you can find this on Youtube if you search "SOA Maniesto"). Could you tell us about what the manifesto was about and its significance?

Art Ligthart: The SOA Manifesto was inspired by the Agile Manifesto of course. It was a turning point in time last year. You could say that for the previous five or six years, we were kind of experimenting with SOA.

We came up with a lot of best practices eventually. Thomas Erl wrote a lot of books about the patterns that he had been collecting some years. You could say SOA has kind of matured now. Big analyst firms such as Gartner have confirmed that SOA has gone through the stages of development.

All of these best practices coming together, means that we can focus less on technologies, on the middleware (which still can be a challenge to implement). We can now focus more on the business value of SOA. You could say that the SOA Manifesto was a turning point in time where we could say "Okay we know what it is now. It's kind of mature. We have to stand aside and start focusing on business services and less about technologies and all the possibilities and impossibilities of that." I think also the economic downturn made it more and more important to talk about the business value of SOA and not just SOA itself.

SOA Magazine: Great! I see that you are involved in many ways in this conference and you will be presenting on various topics and participating as an expert panellist. Is there a particular talk or event you are most excited in participating in?

Art Ligthart: No, I'm a generalist. I enjoy participating in all kinds of sessions and listening to all the expert sessions. As a Chairman, I have to run around all day, talk to and announce speakers, but still, I am able to join the sessions as well. I like to run around and listen to what's going on in the SOA community. I can't really say I'm interested in a particular topic. I like them all.

SOA Magazine: Alright. Thank you very much for joining us today, Art. It was a pleasure talking to you. We will be looking forward to your involvement at this year's SOA & Cloud Symposium in Berlin.

Art Ligthart: I'm looking forward to it too! And it's my pleasure.

Exclusive Interview with Volker Steihl

This edition discusses BPM, BPMN, and SOA with SOA expert Volker Stiehl, a member of the solutions management team from SAP AG. Volker explains the essential distinction of BPMN from BPM, and the relationship between SOA and BPM as such. Volker also discusses his role at SAP, what new innovations he's been a part of, and what more innovations are to come. Volker will be presenting on "Architecture Guidelines for SOA Based Applications Using Executable BPMN: Loose Coupling with Events and Correlation", participating as a panellist on the "Correlating BPM, Workflow and SOA (Where does business analysis end and where does service modeling begin?)" panel, and contributing as a part of the SOA Symposium program committee. Tune in to this very interesting podcast and find out more from Volker himself.

SOA Magazine: How's it going, Volker?

Volker Stiehl: Everything's fine, thank you. And I'm already looking forward to the conference.

SOA Magazine: I just have a few questions to ask you. Could you tell me more about SAP and more about your role there?

Volker Stiehl: No problem. SAP mainly focuses on all kinds of standard business processes. It was founded in 1972 and in the meantime, we have more than 100,000 customers and more than 47,000 employees. Beside those standard business processes, we also deliver technology products. This is actually the area where I'm from. The last five years, I was working for the product management for one of our SOA products - the SAP Net Weaver composition environment. It reflects more or less the consumer side than our SOA Technology. Recently, on the first of August, I moved to the product management of the second SOA product that we are delivering. It's called the SAP Net Weaver Process Integration and it covers ESB functionality.

SOA Magazine: The next question I have for you is actually related to that. What kind of SOA-related projects is SAP working on at the moment?

Volker Stiehl: The projects are all in combination with the products I am working for. I already mentioned two products: the Net Weaver Composition Environment and the Net Weaver Process Integration. Together, they deliver a complete SOA technology that covers the composition side, the provisioning side, the consumption side, ESB functionality, the governance aspect and so forth. We've separated the two products because they are addressing two different kind of processes and from that you can see already that SAP is very much focused on any kind of processes. I mentioned the standard processes already that are covered with our Business Suite products as a pre-delivered, pre-configured business process application. And on the other hand, those technical products and the composition environment is focusing on the consuming side that looks at new business processes that our customers want to build on top of their existing landscapes. It starts really at the early phases of the business processes management, that the business experts work with the IT department, to work in combination on new business processes that target new spaces and new white spaces for the company to improve the business and give them a competitive advantage. So this is what the composition environment is all about. On the other hand, we have the automated processes without human involvement. The composition environment targets processes with a lot of human interaction whereas the process integration focuses on message exchange and processes that are handled automatically in the background where several back end systems are connected via wire message transfer and mapping of those messages between different data formats. So this is the topic that process integration is covering. So in combination, we are delivering a complete SOA technology product that actually covers the whole topic.

SOA Magazine: As a member of the SOA Symposium Program Committee, could you tell us what you think about the current range of topics and the topics that are being covered this year?

Volker Stiehl: Honestly, I am totally excited if I look at the agenda of what is covered in this event. I've never seen an SOA & Cloud event that covers such a broad range of topics. If we look at architecture, design, governance, the combination of SOA with business aspects, having a more technical aspect, it is all covered. We are covering (and this is especially important from an SAP point of view) processes, both sides of the business and project management topic as a whole, and the newly defined standards; the business processes model and notation in particular, which is a very exciting topic, especially in combination with SOA. We have real world use case studies where we can see how SOA is applied in practice. We have the security aspect. We have REST as one of the topics and modern ESB, and so forth and so forth. So in my point of view, as I mentioned, I've never seen such broad coverage and I'm looking forward to hear the presentations and sessions and especially talk with all those excellent experts at the event.

SOA Magazine: Sounds very exciting. This actually relates to my next question. I want to ask you about your presentation. I read your profile on the SOA & Cloud Symposium website and I saw that you will be doing a presentation on SOA and BPM. Could you tell us about BPM and how it is related to SOA?

Volker Stiehl: For me, they really are building a perfect combination. So for me, processes without SOA don't make much sense as well as SOA without processes. If we are starting in our projects with new processes, we have to connect to a bunch of existing landscapes. It is a matter of fact that heterogeneity has to be addressed in all the new solutions that we are building with our customers. And in this regard, SOA is a means to bridge the gap between the new business processes we are going to build and the existing landscapes. So for me, it is the perfect fit. And this is exactly what I want to address in my presentation. I want to work out how we can start from an early process idea, how we will drill down and refine the processes, and how we will all implement the business processes as well as the technical processes. This is pretty new. All on this notation - this BPMN - this Business Process Modeling Notation, it is a strategic standard for SAP. SAP has been working on this specification because it is important for us. We are not using it only on the business side, but we are also using it on the technical composition (how I would call in my presentation). And I will detail out how to really start from a very rough sketch of a process until the very final executable process and how they interact asynchronously, which all based on BPMN. I hope this sounds interesting for the audience and I'm looking forward to the session already.

SOA Magazine: You mentioned notation. What specifically is BMPN? And how is it distinct from BPM on its own?

Volker Stiehl: BPMN is a brand new notation that allows us to model business processes graphically. I sometimes hesitate because it contains the term "business process" inside, but from my understanding it should not only be related to business processes. As I have mentioned, it covers so many technical aspects as well so that it is also a perfect fit for technical processes. And this is exactly what I want to show; that is it not only related to modeling business processes graphically, but also technical processes. On the other side, we have BPM - Business Process Management. This covers much more and there are more aspects. It covers more or less the whole business process lifecycle. It starts with the first analysis of the current situation, how to improve other situations, you model the processes, you develop them, you deploy them, then you run them and interact with your executable processes, you analyze them and finally you want to optimize the processes and the cycle starts all over again. So this is the whole Business Process Management (BPM) lifecycle. And within this lifecycle, the Business Process Modeling Notation (BPMN) is a means to model processes as a foundation for the dialogue between the technical side and the business side. Especially, BPMN is perfectly suitable for this case because it is a notation that is accepted by both parties - the business side and the technical side, and that is brand new. This is a feature we didn't have before. Before that, we had either the technical notations, for example the UML that was used by the technical staff and on the other hand, we had the event-driven process chains that was used by the business side. But either notation was not accepted by the other sides. And this is not the case with BPMN. This is also a very interesting aspect.

SOA Magazine: Thank you Volker for taking the time to talk with me today. We'll be looking forward to your participation and sessions at this year's SOA & Cloud Symposium in Berlin. Thanks again for joining us.

Volker Stiehl: Thank you for giving me the opportunity to tell you what SAP thinks about BPM & SOA. I'm really looking forward to the event.

Exclusive Interview with Stefan Tilkov

In this interview, Stefan talks about the impact and buzz around RESTful servies and SOA, his invlovement in the new "SOA with REST" book and as a committe member and speaker at this years SOA & Cloud Symposium. Stefan will be speaking on "RESTful HTTP: Using the Web for SOA" and will be participating in the "Revisiting the SOA Manifesto" and "Rest Services vs. Web Services - A Live Debate" panels. Tune in for more information straight from Stefan himself. You can also follow Stefan on Twitter at

SOA Magazine: Hi Stefan, how's it going?

Stefan Tilkov: Hi SOA Magazine. Great to be on the show!

SOA Magazine: Can you tell me more about innoQ and your role there?

Stefan Tilkov: I'm one of the co-founder of innoQ and we've started since about ten to eleven years ago. InnoQ is a consulting firm, where we work and help customers with their projects. We also do complete projects with full responsibility with some of our customers and much of the stuff we work with is related to integration and in finding new ways to connect existing systems and to make the best of them. So obviously we've been involved with different approaches in getting there for quite some time. We used to be heavily involved with Web Services. Recently, we've changed a little bit towards RESTful approaches, which is obviously one of my pet topics. We are involved in high level consulting as well as implementation and testing and actually putting stuff into production.

SOA Magazine: Great! I also wanted to ask about the upcoming "SOA with REST" book. Can you tell me how that is going and how you have been participating?

Stefan Tilkov: I've been actually participating as a reviewer. There are many interesting topics and I would love to participate in authoring the book. As we didn't have the time, I was happy to get a chance to have a look at much of the stuff that's in the book. I think it's going to be an exciting and a very good book that actually bridges the gap between a lot of the things that people believe in the classical SOA camp as well as the REST community believes in. I found what I've read to be very very good, but I was also able to add a lot of criticisms as I'm only able to. I hope I've managed to provide some stuff that the authors were able to make sense of. I'm very excited to get a hand on the final copy.

SOA Magazine: That sounds really exciting! I read your bio and you are the author of "REST and HTTP" book. Could you tell us a little more about that book and how it might be different than the "SOA with REST" book?

Stefan Tilkov: The first obvious difference is that the [REST and HTTP] book is actually written in German, so it's "REST und HTTP". So that was one of the key decisions I had to make as to whether I want to write it in English or German. I decided to do at least the first version in German because that's essentially what most of our customers have as their native language. But it's also different content-wise. My book is very much focused on REST and HTTP on a low technical level - So I explain a lot of the HTTP protocol. I have a lot of patterns and RESTful usages. I don't explicitly cover many of the SOA patterns and SOA thoughts that many people have. There is some of that, but not nearly as much as the other book. I do think it goes deeper in some technical aspects, maybe closer to implementation. While it doesn't have any code samples in it, it has a lot of HTTP messages going back and forth and lots of patterns explaining how to design it in a RESTful way that did not explicitly address in a SOA perspective.

SOA Magazine: Another question I have is that as a member of the Program Committee this year, what are your impressions for the submissions so far?

Stefan Tilkov: I think there has been lots of interesting stuff. It's nice to see some of the stuff that would have been deemed exotic last year. Something like Semantic Web and REST are obviously going to be quite different and interesting. And I'm looking forward to exchanging thoughts with some of the people that are going to present there. I'm really looking forward to the discussions that are going on between the sessions as much as I'm looking forward to the sessions themselves.

SOA Magazine: Great! For the last question, I just wanted to know if you have any other SOA projects you've been involved with and if you could give us any details on those?

Stefan Tilkov: We've got a bank that's considering adopting a RESTful strategy across all the systems and they actually started a few minor projects and they have really managed to excite their upper management because they have been able to integrate stuff so quickly and integrate this even with a UI Layer using mash-ups. It's been so impressive that, we have been very enthusiastic about it, including the chance of getting upper management convinced in adopting the RESTful strategy. Another project that I can briefly mention is one where I started doing a classical Web Services introduction workshop and it's in review of existing SOA strategies and I actually ended up mentioning REST in one hour just as a side and actually people were actually so interested in that that by the end of the week, they were fully convinced this is a much better approach.

SOA Magazine: That's very cool. Thank you for taking the time to talk to me today. We'll definitely be looking forward to your session and your participation at this year SOA & Cloud Symposium in Berlin. Thanks again Stefan!

Stefan Tilkov: You're welcome! Thanks for having me.