Tag Archives: soa

OOPSLA’07: The Future of SOA

Yet another panel at OOPSLA discussed SOA, this one entitled “The Future of SOA: What worked, what didn’t and where is it going from here”. Nothing really new came up, compared to the other discussions.

However worth mentioning was Linda Northrop statement that SOA is not an architecture, rather an architectural style at best. Her observation was that SOAs big promise is interoperability, while it forgets all other architectural aspects. My interpretation of this is that the importance of interoperability has been grossly overemphasized while important architectural issues such as quality of service and security is not properly addressed.

Another insight that I got from the panel was that you should not try to build transactions across services, as this will make the services tightly coupled. This was best formulated by Nicolai M. Josuttis, which suggested that instead of using transactions, compensations should be used.

OOPSLA’07: The Role of Objects in a Service-Obsessed World

At OOPSLA, SOA was the subject of many panels, one of them being entitled “The Role of Objects in a Service-Obsessed World”. The panel moderator, John Tibbetts started out by stating that SOA is the worst case of vendor instigated hysteria he has ever seen. Furthermore, he pointed out that he has never seen any architecture in Service Oriented Architecture, and that in SOA there is only marketecture. This was a statement that has been repeated many times on this conference, and that I very much agree to.

Furthermore, Tibbetts went on to describe what he called a marketecture diagram (often used by commercial software vendors, as opposed to an architecture diagram), which have the characteristics of including boxes for virtues (for instance responsiveness), people, and where adjacent blocks may contain products
with overlapping responsibilities. The latter happen of course when the vendor’s product suite has such overlapping products. There is nothing wrong with marketecture diagrames, they may be used to position products. However, they should not be mistaken with architecture diagrams. As a summary, we should get rid of the A in SOA because there is no architecture there.

Another panelist, Jeroen van Tyn, shared his experience on failed SOA projects and pointed out that he has yet to see a SA being driven by the business. Au contraire, SOA is yet another thing that the technology people are trying to sell to the business. Furthermore, he referred to a survey that showed that 70% of the web services out there are being used within the same application, and the big question is of course why the heck we are doing that! He then went on to state that we need to analyze business needs to find a technical solutions, not saying that we have these services and trying to find a business problem to fit into it.

Ward Cunningham was also on the panel, pointing out that in a world of services automated testing across the entire lifecycle of services is a key success factor. In my opinion this is not only a very important factor, it is also one of the most challenging ones. How can we do effective testing across application and organizational bounderies? Furthermore, he pointed out that when you arrive at a large number of services versioning becomes very important. When you have 25 companies exchanging services, how do you make them move at the same time?

Although not on the panel, Dave Thomas contributed to the discussion with (as always) passionate and colourful statements, one of them being that SOA exists only because it is a game that vendors play as a way to control their customers.

Various statements given during the debate:

  • SOA needs to be business driven. (Hm, I seem to recall hearing this before…)
  • SOA has nothing to do with tools
  • SOA does not make change management go away
  • SOA is not a technical issue, it is a business stands
  • BPM is out. (Eh, was it ever in…?)

OOPSLA’07 – SOA and Web Services

After arriving in Montreal Saturday evening, on my first day at OOPSLA, I attended the Fifth International Workshop on SOA & Web Services Best Practices. The workshop consisted of a couple of keynote talks, presentation of papers, and group work.

Olaf Zimmermann stepped in for Ali Arsanjani, giving a keynote on SOA. One of the things he talked about was three central patterns that are central for SOA, namely

  • Service composition
  • Registry
  • Enterprise Service Bus

So, I guess if you have none of these in your architecture, you are not doing SOA. 😉

The second keynote of the day was given Gregor Hohpe, author of the seminal book Enterprise Integration patterns. He talked about the usage of patterns in general, and in the context of integration and SOA in particular. One of the points he made was that the “WebMethod” approach to making services is flawed in the context of SOA. It is certainly buzzword compliant, but that’s all. (By “WebMethod”, I refer to the approach where you declaratively annotates your existing class to generate a Web Service interface for it)

Gregor went on to talk about design patterns in general, and summarized the aspects of design patterns:

  • They are “Mind sized” chunks of information (attributed to Ward Cunningham)
  • They are used for human-to-human communication
  • They express intent (the “why” vs. the “how”)
  • They are observed from actual experience
  • They do not firm a rule (rather guidance)
  • They are not copy-paste code

He also made a point that sketches are important in patterns. However, it should be emphasized that
sketches should not be mistaken with blueprints. Furthermore, he made a point that patterns could effectively be used to test products/frameworks by testing to see that the product or framework could cover design patterns.

Yet another point made (which I think makes much sense) was that declarative programming brings you further away from the execution model, which makes it hard to understand what’s going on, and harder to debug since the the execution path is chosen at run-time. Certainly something to think about, as we see
the use of declarative programming (through annotations in Java, attributes in .NET, XSLT, and various

rules engines) is growing.Looking at SOA and integration in general, Gregor went on to point out that SOA means event-based, asynchronous programming, or “programming without a call stack”. Furthermore, he warned about trying to “program in pictures”. Looking at pictures to understand the architecture is OK, but trying to program pictures brings on problems like scalability, lack of support of diff and merge, etc.Another part of the workshop consisted of group work, where various topics around SOA and web services were discussed.
One of the most important point I think was that we should strive for simplicity in SOA. As vendors bring on more and more products, we should really look at how we can scale down solutions, and make middleware simpler.

OOPSLA Workshop

I attended the 4th International Workshop on SOA & Web Services Best Practices workshop at OOPSLA today. The workshop brings together people with theoretical and practical background with the respect to SOA and Web Services.

Services versioning

One of the things that were discussed was the versioning of (web) services, i.e. how to handle web service upgrades and discontinuance. What we found, with good help from Nico Josuttis who attended the workshop, can be summarized into these three points:

  • Each modified service is a new service
  • Each modified data type is a new data type
  • Don’t use service types in your application

Basically, this gives how you should handle creating new versions of a service while providing older versions of the service to “old” client. The thing is that when you create a new version of the service, that’s a new service that gets deployed aside the old service that clients that are aware of the new version can connect to. Old clients can still, at least for a certain period, connect to the old version. The same goes for data types, typically defined using XML Schema Definitions.
I think that versioning is a very important architectural decision that you need to make when you create services in a large organization, or between organizations, where services and clients have different owners, funding, and life-cycles.

Automated robustness testing

One of the interesting papers submitted to the workshop presented an approach for generated robustness tests for web services from the WSDL of the web service. Basically, the approach was that the WSDL was used to generate tests that could be run using a unit testin tool such as JUnit, and using a tool like JCrasher to generate different kinds of inputs to the web service in order to test that the service is able to handle these. I think this is a good idea that has a lot of potential in automatically assessing the robustness of the service.