Vidar’s Musings

On NDC a couple of days ago, I went to a session where David Chappell talked about Microsoft’s forthcoming “Oslo”. He went to great lengths to not reveal too much, as Microsoft is keeping everything very secret.  In fact, he spent more time explaining what “Oslo” is not than what it actually is.

Figuring actually what is intended to be is not easy. However, from the presentation, we know that “Oslo” is more of a “technology” or “platform” rather than a product. It will consists of the following parts:

• The Repository. It is a storage space that has schemas that defines its data types. Actually what type of information it is supposed to or limited to, is not known. However, examples include things such as process definitions, workflow definitions, IT infrastructure information, and SLAs.
• The Visual Editor. This is a general purpose tool that allows for editing of content in the repository. General purpose meaning that it can be used for different types of data. However, not all communication with the repository need to go through this tool. Special purpose applications or tools can connect and interact with the repository directly.
• Extensions to Windows Workflow Foundation (WF). I am not sure exactly what kind of extensions we will see, but I can guess that it would mean extra activity components.
• The process server. Basically, the WF does not define any host process for running workflow, and the way I figure, the process server implement such a process. It will contain a component called Lifecycle manager that can manage many process host instances (I guess for Load balancing, failover, etc.). The process server will also contain the ability to run BizTalk stuff. A question that comes to mind is whether the process server is “Biztalk for managed code” - built with the capabilities of WF and WCF? Time will show.

So what is the common denominator for all this? I am not sure. I can’t help it, but one word that keeps popping up in my mind is “governance”. Will this be “Microsoft’s tool for IT governance”?

Anyways, the time perspective of this is not known. When will this be available? All we know, is that Microsoft is planning to deliver this in three releases. Will it be in 2009?

Not being sexist at all, I found this blog entry to be quite good: How I explained REST to my wife.

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.

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…?)

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.

I am currently grappling with the challenge of transferring large binary documents in Web Services in an efficient manner. Finally, some of my colleagues came up with the suggestion to use MTOM, which seems to be very promising.

From my initial understanding of the protocol, I would think that MTOM has the  following advantages compared with the approach of including large documents base64 encoded or hex encoded within the SOAP envelope itself:

• Smaller messages - less bandwith intensive communication
• No base64 or hex encoding and decoding needed - less CPU resources needed
• Easier XML parsing since the large document is not included in the XML document (probably both less CPU intensive and memory intensive, depending on the parser)

I would expect that the removal of base64 (or hex) encoding and decoding, together with potentially much swifter XML parsing would significantly lower latency at intermediaries in the value chain. My problem now, is that this is only a gut feeling, rather than hard facts. So, I am preparing to set up a test of MTOM in this respect, with different document sizes to try to measure the differences.

Further reading:

• MTOM
• More thougts on MTOM
• Implement a Web service that deals with complex XML documents

To be continued…