This topic of microservices continues to pop-up in my professional activity.
I remember that some time ago, I heard James Coplien say in a video something like “Microservices…don’t let me start with this”. I wanted to decipher this. Because of that, I re-read his wonderful software architecture book(1) and all of his OOP materials (2).
Small note: I tried to find again the initial video and no luck. Still the words remained in my head. After James reply I realized that I was not off track with my memory.
I have to say from the beginning that this trend regarding microservices is becoming rather dangerous (maybe because of wrong focus or because of misunderstanding of what software architecture really is or because it is not known what OOP actually is or …). I usually say to my friends, colleagues the nightmare we will have in 10 years or so when we will have to maintain the so-called microservices approaches.
What James Coplien said in that video and how he said it hunted me. Then, suddenly, I have found a way to decipher/decompress what he said when I read the paper “The DCI Paradigm: Taking Object Orientation Into the Architecture World”(3). Below are fragments from the article which triggered my thoughts/perceptions/insights:
● “…The authors have been working on a paradigm called DCI(Data, Context and Interaction) that places the human experiences of design and use of programs equally at centre stage…” ➜ Is hard to do that with microservices, they are not about humans at all. The way the subject of microservices is put on the scene is not about human experience at all.
● “…Architecture is the form of any system created through conscious design, and it thus has strong human elements both in its process and its product.The term form implies a deep mental model of the essence of some Structure…” ➜ With microservices it is hard for me to see the holistic form of the system, that’s why I can’t see microservices as architecture. For me is about some low level technical details and about deployments.
●“…Form is the deep essence of what is common between these systems, just as Victorian architecture is the essence of common elements across innumerable houses…” ➜ Here is mentioned the Victorian style, but I thought of the Romanian style named Brâncovenesc(4). James and Trygve are right. When I look at the houses, churches I can say that it is about the Brancovenesc style and I can see that it is different from Victorian style. So, when I look at an HR application or Planning events application I should see that form which speaks about that kind of application. And the fact of what iron or cement was used is another story. I think with microservices it is hard to see the forest from the trees.
●“…Why do we do architecture?It might be useful to revisit some of the key goals of architecture. As mentioned above, Vitruvius reduces the purpose of architecture to utilitas(commodity or utility), firmitas (firmness) and venustas (delight). These goals echo strongly in software, which has adopted them with its own emphases. More broadly, architecture is, and always has been about form. Except among specialists, the English word form is often confounded with structure, and software folks in particular often incorrectly infer that a system’s architecture is the structure of its artefact. The proper architectural usage of the term form has historically been more precise. It’s important to differentiate form from structure: Form is the essence of structure. We can talk in detail about the form of gothic cathedrals even without having a gothic cathedral at hand. Form is the conceptualization of structure in terms of the relationship between parts, and between the parts and their environment. Many given structures can implement a given form, just as there are many (different) gothic cathedrals, all of which implement the forms of gothic cathedrals…” ➜ So, maybe, microservices came with a “structural” flavor and also a simple mechanism of sending/receiving data.
●“…SOA defined services, but at a level that was usually far removed from the code; it is probably a better metaphor for urban planning than for the architecture of a house…” ➜ Yes indeed, this SOA stuff was at the far extremity of the code, just a simple entry point in the system, but nothing else. I was amazed to see whole books regarding how to explain these endpoints and how the entire code structure has been influenced and is not ok.
● “…This may well be because great architectural talent arises from domain knowledge, and it’s difficult to treat architecture as a generic discipline within the (generic) discipline of programming. In the end, architecture has arisen as a generic discipline of tools rather than the result of a quest for beauty and utility…” ➜ The knowing of the domain and its importance is diminished because all the discussions focus on the hammer, scaffold,..
I asked James Coplien to help me out. I really needed his help. He was very kind to review and give me feedback about my insights:<< “Yes” to all of your insights. The main one that bothers me is the lack of a coherent system overview. All understanding is local and the system behavior is taken to be emergent. That doesn’t work except at incredibly large levels of scale and scope.>>(5)
After his feedback I had the pleasure and honor to meet him in person, in Athens. I had participated in 3 of his wonderful trainings about Scrum – a blog post will soon come about this. I hope that soon I will also participate at his DCI training. I am waiting for this DCI training for a very very long time – sometimes I feel this is an impossible dream. Actually, one important reason I decided to have the Scrum trainings with him was the hope to have some minutes with him to discuss about architecture and OOP and it worth it.
(1) James O. Coplien, Gertrud Bjørnvig, “Lean Architecture: for Agile Software Development, https://www.amazon.com/Lean-Architecture-Agile-Software-Development/dp/0470684208/
(2) James O. Coplien, “Publications”, https://sites.google.com/a/gertrudandcope.com/info/Publications
(3) James O. Coplien, Trygve Reenskaug, “The DCI Paradigm: Taking Object Orientation into the Architecture World”, https://doi.org/10.1016/B978-0-12-407772-0.00002-2
(4) “Brâncovenesc style”, https://en.wikipedia.org/wiki/Br%C3%A2ncovenesc_style
(5) Text used with permission (March, October 2019)
Very interesting write-up, thank you for sharing your views. I’d add up that the vibe about microservices has been amplified by the practices such as Dev(-Sec)Ops and the “need” to be efficient, reduce waste / technical debt, etc. and focus on delivering more value, rather than wasting time on “plumbing”, which in itself is great, though not suficient. The other aspect is that DDD is a great architectural style, not new and with limited application (requires certain practice to be efficient at it), and microservices benefit greatly from it. In my mind microservices should not be the target in an architect’s journey, and many force it because it is trend.