Incubator Module: Changing the Way We Work With Java

Incubator Modules: Transforming Java's Evolution

The Java platform has been the bedrock of enterprise application development for over two decades. Its portability, scalability, and vibrant ecosystem make it ubiquitous across industries. However, the traditional Java SE release model faced challenges in keeping pace with rapidly changing business and technology landscapes.

To enable swifter innovation, Oracle introduced incubator modules in Java 9. Incubator modules provide a formal process to deliver experimental APIs for developer collaboration and feedback before full standardization.

This article will explore how incubator modules are transforming Java's evolution to be more agile and community-driven. Java development India examine the limitations of the traditional model, the workings of incubator modules, their benefits, and their use cases.

Challenges With the Traditional Java Module System:

Java has historically relied on a standardized release cycle for introducing new capabilities, which posed multiple limitations:

Long Release Cycles: Major Java SE platform updates occurred every 2-3 years, while incremental updates occurred yearly. This release cadence struggled to match the fast-changing technology landscape, where business requirements evolve more rapidly.

Prolonged Standardization: The Java Community Process allows new APIs and architectures to be proposed as Java Specification Requests. However, the JSR approval process is lengthy and can take 1–2 years.

Lack of Agility: New technologies and methodologies like cloud, containers, microservices, and DevOps require greater agility. However, Java platform evolution was not as dynamic or driven by user feedback.

No Experimental APIs: There was no formal process to introduce experimental APIs for developer feedback before full standardization. Hence, gauging initial user traction was difficult.

Insufficient Community Involvement: Collaborative development between Oracle and the developer community was limited. Platform evolution was not open and participatory.

Upfront Specification: APIs require comprehensive upfront specification and approval before release, rather than starting small and iterating.

Risk of Premature Release: APIs often get standardized without sufficient real-world testing, resulting in quality issues later.

Delayed Feedback Loops: It took too long to get developer input on new APIs with prolonged release cycles.

Lack of Agile Practices: The release model did not align with agile and iterative development methodology best practices.

Incubator Modules - An Overview:

The incubation phase will permit new Java APIs to be delivered as a preview to developers through incubator modules without committing to standardizing them yet. It will lower the risk of introducing major changes that may not work as intended. Developers can choose to opt in and try out experimental APIs based on their needs and project timelines.

During incubation, APIs are not given any compatibility or backward compatibility guarantees. This freedom permits more aggressive exploration and evolution of new ideas without stability concerns. Developers understand the APIs may change or be removed based on feedback. But it also means issues can be identified and addressed early, before standardization.

Incubator modules follow a loose versioning model compared to standard modules. New incubating APIs can be added or removed across minor and major version updates as needed. This dynamic and flexible model helps shape APIs rapidly through an iterative process. In contrast, standard modules adhere to a more rigid versioning contract once released.

The incubation period typically lasts 1-2 years to allow sufficient testing and feedback gathering. During this time, usage metrics, issue reports, code samples, and reviews from various projects are analyzed. Community discussions and feedback channels like mailing lists also provide qualitative input. All this helps determine if an API is mature enough or needs more work before standardizing.

Some examples of APIs that underwent incubation include HTTP Client, JEP 223, JEP 320, and others. Based on the learnings from their incubation, these APIs were refined and became standardized parts of Java with later releases after addressing compatibility and other concerns raised.

The incubator module approach has proven very effective for Java evolution. It balances the need for innovation with stability concerns. New ideas can be delivered quickly for testing while avoiding the risks of destabilizing the platform prematurely. The community feedback integrated iteratively shapes APIs that better serve real-world use cases.

How Do Incubator Modules Work?

Incubator modules have three key characteristics:

  • Dynamic Evolution: Incubator module APIs can evolve rapidly between releases. Their APIs may change significantly or even be entirely removed based on user feedback.
  • Openness to Feedback: The emphasis is on gaining practical feedback by enabling developers to try out incubating APIs in projects and share inputs.
  • Encapsulation: Each incubating API is encapsulated in its dedicated module for easy testing rather than clubbing with other modules.

Incubator modules go through a structured process:

  • Oracle identifies promising new APIs that are not ready for formal release.
  • These APIs are packaged into isolated incubator modules for developer use.
  • Metrics on adoption, bugs, and critiques are gathered during the incubation period.
  • Feedback helps refine API design and determine its future standardization.
  • An incubating API graduates as a standard module or gets removed after incubation.

Use Cases For Incubator Modules:

Incubator modules offer value in several scenarios:

  • Early-Stage Development: API designers can get feedback from real usage to evolve innovative APIs before formal release.
  • Community Collaboration: The Java community can collectively shape new capabilities through hands-on usage and sharing inputs.
  • Third-Party Libraries: Established open-source third-party libraries can first be incubated to determine suitability as a standardized API based on metrics.
  • Agile Evolution: Enables experimentation and agile evolution of platform capabilities aligned to the latest industry needs.

Perks Of Incubator Modules:

The primary perks provided by Java incubator modules include:

  • New APIs can be assessed by developers without prolonged release cycles.
  • Incubation provides empirical data to determine API readiness and prevent premature release.
  • Developer participation spurs innovation through rapid prototyping of new capabilities.
  • APIs can evolve incrementally via community collaboration rather than upfront specification.
  • Real-world usage exposes defects and reliability issues early on.


Incubator modules introduce greater agility and community participation in evolving the Java SE platform through collaborative experimentation. They overcome the bottlenecks of prolonged standardization cycles and bring Java’s evolution into line with today’s dynamic business environments.

This developer-centric model results in higher-quality APIs shaped by real-world feedback. Contact leading Java development companies to leverage incubator modules and contribute to Java's innovation. With a strong focus on developer experience, Oracle continues to enhance the Java platform's versatility to support next-generation enterprise applications.

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