Microservices and the role of Domain-Driven Design

In our #SATURN15 talk From Monolith to Microservices we addressed the challenge of data centric development, particularly when behaviour rich domain models are needed.

One of our main point in the talk was that too many developers continued with their script like programming style when they moved to Object-Oriented programming languages. Objects was treated as records and they seamed to have forgotten or never learned that object-oriented programming is all about capture of domain  behaviour and knowledge.

After reading the introductory chapter of @VaughnVernon book Implementing Domain-Driven Design this weekend another aspect became evident. The negative influence of properties and property sheets, originally introduced by Microsofts Visual Basic in 1991 and later copied by the JavaBean specification. These innovations dumbed objects down to records and even worse, trained developers to think this was the right way to design software using objects.

For Microservices to survive it is time to take object-oriented modelling back. Developers must learn that objects and object oriented programming supported by domain-driven design provides the tooling and techniques required to build behaviour rich software.  Software that not only capture data, but also domain behaviour and knowledge and make it executable.

The claim is that Microservices without sufficient capture of rich domain behaviour and knowledge will not add sufficient business value. They will just end up as distributed balls of mud.

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