Federated Microservices

From Many, One

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·Jun 2, 2021·

4 min read

Federated Microservices

What are federated microservices?

Federated microservices are the independently deployable components of a federated application. In a federated application, components are loaded from multiple network locations and repositories at runtime. They are not developed by a single team or built from a single codebase. Multiple federated application components can run in a single application instance; and can be redeployed at any time, without restarting the application or interrupting other components that happen to be running.

Why are federated microservices needed?

Incidentally, the word “federation” accurately describes the structure of the development organization microservices enables: one made up of small, independent teams with internal autonomy. Let’s consider what provides this autonomy and what role distributed systems architecture, or simply “distribution,” plays.

What is the purpose of distribution in a microservices architecture: scalability, polyglossia, deployment independence? It enables all three. But which properties are indispensable to the kind of organization we want to support? If we conflate concurrency of users with concurrency of developers, we could say scalability is essential. But in the proper sense of the term, you can also scale a monolith. The same options are available: horizontal, vertical, component-wise (e.g. target hot parts of the app with a load balancer). If that doesn’t satisfy, consider that all frontends were monolithic not too long ago. Relative to backend microservices, micro-frontends are recent. As for polyglossia, it does open up the potential developer pool and language fitness for purpose. But what makes each team able to innovate at their own pace without being dependent on the activities of the others? Clearly, its deployment independence.

An image taken from martinfowler.com and modified to include federationAn image taken from martinfowler.com and modified to include federation

So while distribution may make it easier to scale, scalability is not a reason for implementing microservices. You don’t abandon your monolith because it doesn’t scale, at least in the traditional sense of that word. You abandon it because lack of modularity and proper organization has rendered the codebase brittle and difficult to change or augment as business requirements evolve or your organization grows. The main reason for distribution is deployment independence. Without it, teams cannot work at their own pace. They have to coordinate releases and new features have to wait. When you consider the impact this has on the speed and alacrity of the development organization and the business as a whole, scalability and polyglosia look more like side-effects than solutions.

The problem is that distribution increases complexity, and not insignificantly. While it ensures modularity, as every component is now isolated by a hard-and-fast boundary, the network, it makes component interactions harder to develop and the system as a whole harder to manage. What was previously an in-memory function call is now a network call. An entirely new set of circumstances apply. The application will take longer to code and will be harder to test and deploy. Test and deployment automation are absolutely required. Performance will degrade. Troubleshooting will be more difficult, et cetera.

All of this raises the barrier to entry for organizations looking to benefit, not from distributed systems, but from deployment independence. Up to this point, putting up with the microservice premium, as its known, was simply considered a trade-off, not a problem with a potential solution. (Although the solution is commonly mentioned in descriptions of the problem.) The result is a disproportionately high degree of failed implementations, missed opportunity for those forewarned of failure, and growing operational complexity. Consider the *death star* effect.

Given all the trouble with distribution, it seems reasonable to ask if there isn’t a way to implement deployment independence without it. Can’t we deploy our services independently without having to distribute them as separate executables communicating over a network? In case you missed the first section, the answer is, “yes”. In the next article, we will see how federated applications can solve this and other related problems, with technologies such as: **self-deployment, distributed object caching, transparent integration, and module federation. You can find a preview of this tech here. [Stop Paying the “Microservice Premium”* Achieving Deployment Independence in a Monolithic Architecture*trmidboe.medium.com](https://trmidboe.medium.com/discounting-the-microservice-premium-a95311c61367)

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