In our recent posts, we’ve tried different configurations for our Mule projects with parent POMs and BOMs. But you might be wondering? Are they not just the same? Are they different? And if so, which one should we use for our Mule projects?
We've got you covered. In this post, we will answer all of these questions.
Difference between parent POM and BOM
In Maven, both the parent POM and the BOM (Bill of Materials) play important roles in managing dependencies and project configuration, but they serve different purposes. In MuleSoft projects, understanding the distinction between the two is crucial to maintaining a clean, consistent, and scalable setup for multiple projects. These are the main differences:Purpose
The primary use of a BOM is to ensure that different Mule apps that depend on the same libraries (e.g., Mule runtime, connectors, plugins, third-party libraries) use consistent versions of these dependencies. This helps avoid version conflicts between dependencies by controlling the versions of transitive dependencies.A parent POM is used to define common configurations that are shared across multiple projects. It centralizes common build settings, plugin configurations, dependency management, and properties that multiple child projects can inherit.
Scope
The parent POM manages:- Common dependencies (connectors, libraries)
- Common plugins configurations (e.g. mule maven plugin)
- Common properties (e.g. mule runtime version, anypoint client id)
- Profiles - to manage different environments
- Repositories
Inheritance
When a Mule app uses a parent POM, it will import all the dependencies, plugins, repositories... included in the parent POM. In other words, the effective POM of each child project will merge parent and child POMs. For example, if we’ve got 10 connectors in a parent POM, each child project will include those 10 connectors in the build.When a Mule app uses a BOM it does not inherit anything. What happens is that for each dependency or plugin, the child project will just pick up the version number of that dependency from the BOM. In the previous example, if we’ve got 10 connectors in a BOM, each child project won’t necessarily include those 10 connectors, it will only include those connectors directly specified in the child project’s POM. And for those connectors, the version will be imported from the BOM.
Conclusion
POM and BOM are not the same, we don’t have to choose between one or the other. In a Mule setup, we should use both.We should use a parent POM to manage common configurations and properties, and we should use a BOM to ensure all projects use the correct versions of Mule runtime and connectors.