DRY principle with Microservices

When working with development teams transitioning from a monolithic applications to microservices I sometimes face their anxiety of breaking the ๐——๐—ฅ๐—ฌ (๐—ฑ๐—ผ๐—ป’๐˜ ๐—ฟ๐—ฒ๐—ฝ๐—ฒ๐—ฎ๐˜ ๐˜†๐—ผ๐˜‚๐—ฟ๐˜€๐—ฒ๐—น๐—ณ) ๐—ฝ๐—ฟ๐—ถ๐—ป๐—ฐ๐—ถ๐—ฝ๐—น๐—ฒ.

๐—ช๐—ต๐—ฒ๐—ป ๐˜€๐—ฎ๐—บ๐—ฒ ๐˜๐—ฒ๐—ฎ๐—บ ๐—ถ๐˜€ ๐˜„๐—ผ๐—ฟ๐—ธ๐—ถ๐—ป๐—ด ๐—ผ๐—ป ๐—บ๐˜‚๐—น๐˜๐—ถ๐—ฝ๐—น๐—ฒ ๐—บ๐—ถ๐—ฐ๐—ฟ๐—ผ๐˜€๐—ฒ๐—ฟ๐˜ƒ๐—ถ๐—ฐ๐—ฒ๐˜€ ๐˜๐—ต๐—ฒ๐˜† ๐—ฎ๐—ฟ๐—ฒ ๐—ถ๐—ป๐—ฐ๐—น๐—ถ๐—ป๐—ฒ๐—ฑ ๐˜๐—ผ ๐—ฒ๐˜…๐˜๐—ฟ๐—ฎ๐—ฐ๐˜ ๐—ฐ๐—ผ๐—บ๐—บ๐—ผ๐—ป ๐—ฐ๐—ผ๐—ฑ๐—ฒ ๐—ฎ๐—ป๐—ฑ ๐—ฟ๐—ฒ๐˜‚๐˜€๐—ฒ ๐—ถ๐˜ ๐—ฎ๐—ฐ๐—ฟ๐—ผ๐˜€๐˜€ ๐—บ๐—ถ๐—ฐ๐—ฟ๐—ผ๐˜€๐—ฒ๐—ฟ๐˜ƒ๐—ถ๐—ฐ๐—ฒ๐˜€.

If you are inclined to do the same then think about the ideas bellow.

1. Having classed named the same in multiple microservices (for example Customer in both Checkout and OrderManagement microservices) is not a violation of the DRY principles. It is a consequence of ๐˜ด๐˜ฆ๐˜ฑ๐˜ข๐˜ณ๐˜ข๐˜ต๐˜ช๐˜ฐ๐˜ฏ ๐˜ฐ๐˜ง ๐˜ค๐˜ฐ๐˜ฏ๐˜ค๐˜ฆ๐˜ณ๐˜ฏ๐˜ด between two different ๐˜ฃ๐˜ฐ๐˜ถ๐˜ฏ๐˜ฅ๐˜ฆ๐˜ฅ ๐˜ค๐˜ฐ๐˜ฏ๐˜ต๐˜ฆ๐˜น๐˜ต๐˜ด .

2. Duplicating functionality in multiple microservices is usually a sign of bad design. A microservice should have only one responsibility – ๐˜ด๐˜ช๐˜ฏ๐˜จ๐˜ญ๐˜ฆ ๐˜ณ๐˜ฆ๐˜ด๐˜ฑ๐˜ฐ๐˜ฏ๐˜ด๐˜ช๐˜ฃ๐˜ช๐˜ญ๐˜ช๐˜ต๐˜บ ๐˜ฑ๐˜ณ๐˜ช๐˜ฏ๐˜ค๐˜ช๐˜ฑ๐˜ญ๐˜ฆ .

3. Data repetition – multiple microservices owning same data – is generally a bad practice and should be avoided.

And don’t forget to apply principles pragmatically!