Apache Continuum

Overview

Apache Continuum was a continuous integration (CI) server developed by the Apache Software Foundation. It was designed to automate the process of building, testing, and deploying software projects, thereby facilitating the continuous delivery of software. Continuum was part of the Apache project suite and was particularly aligned with Apache Maven, a build automation tool used primarily for Java projects. The software was written in Java and was distributed under the Apache License 2.0.

Features

Apache Continuum provided a range of features that supported the CI process:

**Build Automation**: Continuum automated the build process by integrating with various version control systems such as Subversion, Git, and CVS. It supported the scheduling of builds and could trigger builds automatically when changes were detected in the source code repository.

**Build Management**: The software offered comprehensive build management capabilities, including build history tracking, build result notifications, and the ability to manage multiple projects and build environments.

**Integration with Apache Maven**: Continuum was tightly integrated with Maven, allowing it to leverage Maven's project object model (POM) for dependency management and build configuration. This integration enabled Continuum to automatically resolve dependencies and execute Maven goals as part of the build process.

**Build Reporting**: Continuum provided detailed build reports, including logs, test results, and metrics. These reports were accessible through a web-based interface, allowing developers to monitor the status of their builds and identify issues quickly.

**Role-Based Access Control**: The software included a role-based access control system, enabling administrators to define user roles and permissions. This feature ensured that only authorized users could access certain functionalities or modify project settings.

**Extensibility**: Apache Continuum was designed to be extensible, allowing developers to create custom plugins to extend its functionality. This extensibility made it possible to integrate Continuum with other tools and systems in the software development lifecycle.

Architecture

Apache Continuum's architecture was based on a client-server model. The server component was responsible for managing the build process, while the client component provided a user interface for interacting with the server. The server was built on top of the Apache Plexus framework, which provided a modular and component-based architecture.

The core components of Continuum included:

**Continuum Core**: The core module was responsible for managing the build lifecycle, including the scheduling and execution of builds. It also handled the integration with version control systems and the retrieval of source code.

**Continuum Web Interface**: The web interface was the primary means of interacting with Continuum. It provided a user-friendly interface for configuring projects, monitoring builds, and accessing build reports.

**Continuum Database**: Continuum used a database to store build information, project configurations, and user data. The database supported multiple backends, including MySQL, PostgreSQL, and Apache Derby.

**Continuum Agents**: In distributed build environments, Continuum could be configured to use build agents. These agents were responsible for executing builds on remote machines, allowing for parallel and distributed build execution.

Integration with Other Tools

Apache Continuum was designed to integrate seamlessly with other tools in the software development lifecycle. Some of the key integrations included:

**Version Control Systems**: Continuum supported integration with popular version control systems, allowing it to automatically detect changes in the source code and trigger builds.

**Build Tools**: While Continuum was primarily designed for use with Apache Maven, it also supported other build tools such as Apache Ant and shell scripts. This flexibility allowed it to be used in a variety of build environments.

**Notification Systems**: Continuum could be configured to send build notifications via email, instant messaging, or other notification systems. This feature ensured that developers were promptly informed of build results and failures.

**Issue Tracking Systems**: Continuum could be integrated with issue tracking systems such as JIRA and Bugzilla. This integration allowed build failures to be automatically linked to relevant issues, facilitating faster resolution.

Use Cases

Apache Continuum was used by organizations of all sizes to streamline their software development processes. Some common use cases included:

**Continuous Integration**: Continuum automated the build and test process, enabling developers to integrate code changes frequently and detect integration issues early.

**Continuous Delivery**: By automating the deployment process, Continuum facilitated the continuous delivery of software, allowing organizations to release new features and updates more frequently.

**Quality Assurance**: Continuum's build reporting and notification features helped organizations maintain high-quality software by ensuring that code changes were thoroughly tested before being deployed.

**Distributed Builds**: In large-scale projects, Continuum's support for distributed builds allowed organizations to leverage multiple build agents to execute builds in parallel, reducing build times and increasing efficiency.

Discontinuation and Legacy

Apache Continuum was retired by the Apache Software Foundation in November 2016. The decision to retire the project was based on several factors, including the availability of more modern CI tools and a decline in community activity. Despite its retirement, Continuum left a lasting legacy in the CI space, having influenced the development of other CI tools and practices.

Organizations that previously used Continuum have since transitioned to other CI solutions, such as Jenkins, Travis CI, and GitLab CI. These tools offer more advanced features and better integration with modern development workflows.