Spring Boot, a popular framework for creating standalone, production-grade Spring-based applications, follows a specific versioning convention that helps developers manage dependencies and ensure compatibility across different versions. Understanding this versioning scheme is crucial for developers who work with Spring Boot, especially when upgrading applications or resolving compatibility issues.

Version Numbering Scheme

Spring Boot uses a versioning scheme that follows Semantic Versioning principles with some modifications. The versioning format is generally ```<MAJOR>``.``<MINOR>``.``<PATCH>```, with the following meanings:

• Major Version: This number is incremented when the release contains breaking changes that are not backward compatible.
• Minor Version: This increment occurs when new functionality is added in a backward-compatible manner. It also includes updates, such as new features and improvements, that do not break existing functionality.
• Patch Version: Increments when backward-compatible bug fixes are made. This can include security fixes, optimizations, and patches to existing features.

Spring Boot extends this versioning principle by distinguishing between development and production readiness through milestones, release candidates, etc., using the Pre-Release Versioning Indicators as outlined below:

• `M`: Milestone (e.g., `2.5.0-M1`)
• `RC`: Release Candidate (e.g., `2.5.0-RC1`)
• `SNAPSHOT`: Indicates ongoing development for a particular version. SNAPSHOT versions are unstable and reflect the most recent code changes.

Upgrading Spring Boot Versions

When upgrading versions, it's essential to follow these best practices:

1. Review Release Notes: Always inspect the release notes for new features, changes, and known issues that may impact your application.
2. Test Thoroughly: Before deploying a new version to production, rigorously test your application against the new version.
3. Manage Dependencies: Use the Spring Boot Dependency Management plugin to keep track of the versions of your dependencies.

Here is an example of how the versioning might appear when using these principles:

• `2.4.0`: A new minor version with added functionalities compatible with the 2.x major release.
• `2.4.1`: A patch release with bug fixes for the `2.4.0` version.
• `2.5.0-M2`: The second milestone of the 2.5.0 release series.
• `2.5.0-RC1`: The first release candidate for the 2.5.0 version, being one step away from the final release.

Summary Table

Here is a summary table of the Spring Boot versioning scheme:

Additional Considerations

Dependency Management

Spring Boot simplifies dependency management by providing a curated list of dependencies, known as "Starters," that work well together. The spring-boot-dependencies POM defines the versions of these dependencies to maintain consistency and compatibility.

Version Compatibility

When choosing dependencies within Spring Boot applications, ensure they align with the supported versions. The Spring Boot team's compatibility guarantee pertains to dependencies aligned with the version of Spring Boot you are using.

Consultation with Spring Initializr

Utilize the Spring Initializr (https://start.spring.io/) to generate a Spring Boot project with a predefined configuration. This tool ensures you start with a compatible set of dependencies and the latest stable version (unless specified otherwise).

Conclusion

Understanding Spring Boot's versioning convention is vital for any developers working within the Spring ecosystem. By following the semantic versioning scheme with its extensions for milestones, RCs, and snapshots, developers can effectively manage their applications across different versions. Whether it's a small patch or a major release, being aware of these conventions will help you maintain a stable and efficient development and deployment process.