I've been designing, developing and otherwise involved in distributed systems for 30 years. I love the challenges they present, especially around my own speciality of fault tolerance. Whether it's different consensus models, the duality of orchestration and choreography, replication techniques or different transaction models, to name but a few, working with distributed systems is thought provoking. And in today's world of ever connected devices at scale, it's even more so than at any time in the last decades.


There are many good architectural reasons why you might want to, or need to, employ a distributed approach to your application. Code you rely on may be running elsewhere to your own business logic, may be implemented in a different language, or may need to be replicated to improve availability, for instance. It may even be the case that your distributed system evolved over time from a more localised implementation, e.g., a capability you wrote now needs to be shared between groups and it makes sense to replicate copies physically closer to them.


Distributed systems make a lot of sense for many applications and developers. In the words of RFC2119 they MAY help to solve some particularly tricky issues but they WILL cause other problems of which you MUST be aware. Distributed systems are great. But you know what? A centralised system may be far more appropriate for what you need. Why do I mention this and why do I think it's important that developers and business owners realise this? Because if you listen to our industry at the moment you'd be forgiven for believing that all applications need to be decomposed into (micro) services, each residing in its own (Linux) container and communicating using HTTP (hopefully at least using REST too).


If you've got a centralised system that doesn't mean it's necessarily a monolith. Likewise distributed systems aren't necessarily more agile, lean or less monolithic in nature. As a developer, architect or business owner you shouldn't feel ashamed to admit "I'm centralised and I'm proud!" Don't feel that microservices are going to solve architectural problems due to their distributed nature and if they do, they will definitely introduce challenges you don't have to worry about in a local environment. Now don't get me wrong, I appreciate the ideas around microservices as they are influenced by SOA and other experiences over the years. Unfortunately some of those who are pushing microservices strongly fall into one or more of the following categories: they don't care to learn about distributed systems, they don't believe they have the time to learn about the pitfalls of distributed systems (our industry moves at a pace), they have an agenda which isn't necessarily conducive to your productivity, or maybe they really do believe they're doing the right thing by adopting these new fangled ways. And of course there are proponents of microservices architectures who really do understand the trade-offs they represent and will faithfully represent them to you so you can make an informed choice.


Furthermore, citing examples of successes such as Netflix or Amazon is hardly being fair to the large numbers of applications and vendors who don't use distributed systems, let alone microservices, and would still consider themselves to be successful. Of course there are things we can learn from the likes of Netflix. Of course there are lessons we can apply when considering microservices. But just because you are developing a centralised system does not mean you are a failure or should be consigned to the garbage can of history!


Alright, if you've read this far you would be forgiven for thinking I don't like microservices. But you'd also be missing the point. Just as we've been shown over the years that writing distributed systems is often necessary and a core requirement for some applications, so too is developing using a microservices architecture. What I'm trying to show though, is that you'd better understand why you need to distribute your services as well as the fundamental implications that such an approach entails. And maybe, just maybe, going back to, or remaining, centralised is really the right thing for you.