Architectural patterns for modular monoliths that enable fast flow

architecting   modular monolith   fast flow  

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In this article, I describe three architectural patterns for modular monoliths. These patterns are based on my experience developing both monoliths and microservices.

You will learn about these and other patterns in my Architecting for fast flow: enabling DevOps and Team Topologies workshop, 9am-11am CET/4pm-7pm Korea Time, September 23th-25th, 2024. 20% discount for groups of 6 or more.

Designing monoliths for fast flow

The primary concerns when using the monolithic architecture pattern are:

• Managing the complexity of a large codebase
• Maximizing team autonomy despite the single code base
• Accelerating the single deployment pipeline in order to still provide fast feedback

There are three patterns that address these concerns:

• Modular monolith, aka. domain-oriented monolith
• Domain module API
• Domain API build module

Let’s first look at the modular monolith pattern.

Pattern: Modular monolith, aka. domain-oriented monolith

Organize a monolith as a collection of loosely coupled, domain modules that are based on DDD subdomains/bounded context rather than technical layers in order to manage complexity and improve team autonomy.

For more information, see The modular monolith, which introduces the basic idea, and No such thing as a modular monolith, which explains why the term ‘modular monolith’ is a misnomer.

Pattern: Domain module API

Encapsulate each domain module’s implementations details, which includes its database schema, behind a stable, facade-style API in order to reduce loose design-time coupling between modules and improve testability.

For more information, see Encapsulating the customers domain behind a facade.

Pattern: Domain API build module

Define a separate build module (e.g. Gradle subproject) for the domain module’s API, which the domain module’s clients depend upon (rather than the implementation), in order to reduce build-time coupling and accelerate the deployment pipeline.

For more information, see Using domain API modules to reduce build-time coupling.

Want to learn more

You will learn about these and other patterns in my Architecting for fast flow: enabling DevOps and Team Topologies workshop, 9am-11am CET/4pm-7pm Korea Time, September 23th-25th, 2024. 20% discount for groups of 6 or more.

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