The subject, as the title indicates, is micro services, which in many ways is a response to monolithic architectures. As with SOA, Micro Services also lack a clear definition . The only thing people seem to agree on is that Micro services are smalland they are individually deployable . Rule of thumb says that Micro services weigh in around 10-100 lines of code (for languages with minimal ceremony and excl. Frameworks and libraries – although the last point is disputed among purists). Number of lines of code is in my opinion a horrible measuring stick for determining whether a (micro) service has the correct size or for that matter if it is a good service.
Good guidelines for designing micro services in terms of scope (size) and integration form (how to use them) seems to be lacking. Without these guidelines it becomes difficult to separate the wheat from the chaff and one could easily be tempted to claim that the layered SOA (anti) pattern (see diagram below) also meets the micro service size rule of thumb (and then we know that some people will be tempted to cross off micro services on their list and say that they have them too, without looking closely at what micro services is all about and therefore never will come near designing proper micro services).
I read the other day that the new system Proask for the National Board of Industrial Injuries in Denmark, was the first major project that would realize the Ministry of Employment strategic decision to use a Service Oriented Architecture ( SOA). For those who have not heard of Proask, it is yet another strongly delayed public project which, like most other public projects, are trying to solve a very big problem in a large chunk. A lot can be written about this approach, but in this blog post I will focus on here is their approach to SOA. A related article reports that the new Proask system is 5 times slower than their old system from 1991.
The Proask project was initiated in 2008. It made me think back on that other ( private) SOA prestige project from the same period, for which I was an architect for a subcontractor. The entire project was built around SOA with many subsystems that would deliver services. The entire architecture was built around an ESB that would act as facilitator in terms of mapping and coordination. All communication was done as synchronous WebService calls over HTTP(S). So classic SOA for the period 2003-201? (sadly synchronous calls are still the predominant integration form today). This SOA realization was also characterized by very poor performance, high latency and low stability.
There is an interesting change in the approach to SOA and it comes from an unexpected area.
I have worked with SOA (a great acronym which really says nothing as it has been watered out) for over 10 years and through my time I have seen companies build more and more hierarchy (or rather layers) and structure into their SOA landscape as a way to achieve “business agility through business and IT alignment and increased recycling”. If you tend to get a gag reflex by hearing the phrase, I feel you.
The idea and the intention is good, but the execution many places is to the grade F-. Instead of having achieved agility through loosely coupled services, these companies instead end up with hard-coupled services, an expensive and cumbersome organizational Enterprise Service Bus (ESB), which is placed centrally to coordinate the hundreds to thousands of services we have built. It is a bit like herding sheep with a chest freezer and a rope tied to each sheep.
Let me make it clear, I don’t believe SOA, nor the ESB, is to be blamed for these failures. In my experience it has been the way they were implemented and deployed that cause the majority of problems.
It’s messy and unstable. Not unstable as in the ESB is unstable, but unstable in that we’re desperately trying to create order out of chaos without understanding the mechanisms of action.
Let me make it clear, I don’t believe SOA, nor the ESB, is to be blamed for these failures. In my experience it has been the way SOA were implemented and deployed that has caused the majority of problems. Continue reading “SOA – Hierarchy or Organic growth?”→
Most companies today use SOA to integrate their systems or mobile applications, or do they?
Join me on a historical trip where we will see how integration has remained stuck in the same patterns and we will also take a look at the emperors new clothes (or SOA as it’s practiced today).
After this we will look at how to do SOA better and the principles that will make this transition possible (keywords: Event Driven Architecture, Domain Driven Design, Composite UI’s and CQRS)
Saying that you’re a .NET shop, a Java shop or some other programming platform shop is just as ridiculous as if a software tester is saying that he is just a BDD man. Hopefully he is much more than that and has a more balanced approach to software testing, so he can select that test approach that makes the most sense for the problem at hand. Wouldn’t you be worried if you went to your car repair shop and were told that they’re only a piston shop? Continue reading “I’m a .NET shop vs. I’m a Java shop parody”→