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javaspringspring-bootmicroservicesspring-cloud-netflix
Punter Vicky
Punter Vicky

Reputation: 16992

Adding dependencies to microservices

I have built few microservices that consume a number of external services. Few of these external services are consumed by more than 1 microservice that I have built. I have built the connectors to these microservices as a library project and have included it as a dependency in all my microservice projects. However I read that all logic for microservices should be self contained and duplication of logic is ok. If that's the case , is it recommended for me to define these connectors within each every microservice instead of having a shared library?

Upvotes: 3

Views: 1165

Answers (1)

tom redfern
tom redfern

Reputation: 31760

...all logic for microservices should be self-contained and duplication of logic is ok

I think this is the core of the issue you are struggling with. Is this statement actually true?

A quick google search later: http://www.simplicityitself.io/our%20team/2015/01/12/sharing-code-between-microservices.html

This article talks about this exact question, which we can now frame as What is the appropriate level of re-use in microservice architecture?

The author provides a list of reasons why developers feel the need to share code, ordered from lowest to highest in terms of coupling and loss of isolation:

  • Leverage existing technical functionality
  • Sharing data schemas, using a class, for example, as an enforcement of a shared schema.
  • Sharing data sources, use of the same database by multiple services.

Though this list covers most of the reasons, I would add another important reason to share code, which is to do with a common framework for rapid standing up of microservices, commonly called the Microservice Chassis pattern.

The author goes onto say:

It is of utmost importance to pin down your motivation for wanting to share code, as unfortunately there is no right answer to this question. Like everything else, it’s contextual.

So, all that said, should you centralize your connectors or not?

Well, where do these dependencies fit in on our list? And what degree of coupling can you endure before you're no longer doing microservices but building a monolith instead?

These are not easy questions to answer, but hopefully this will help guide you to the correct conclusion.

Upvotes: 3

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