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Apache StrutsEdit

Apache Struts is a free, open-source web application framework for building Java-based web apps. It implements the Model–View–Controller (MVC) pattern and provides a structured way to assemble controllers, views, and data models in enterprise environments. Developed and maintained under the auspices of the Apache Software Foundation, Struts has played a major role in Java web development since the early 2000s, particularly in large organizations with long-lived, mission-critical systems.

Struts emerged as a practical solution for organizing complex web applications around a front controller concept. By centralizing request handling and navigation decisions, it aimed to reduce duplication, improve maintainability, and enable teams to enforce consistent patterns across diverse projects. The project offers a rich set of tag libraries, form handling capabilities, and integrations with JSPs and other view technologies, making it a capable toolbox for building robust web interfaces. For developers, Struts also embodied a philosophy of configurability and extensibility that aligned with enterprise needs for predictable behavior and governance in software lifecycles.

History

Apache Struts traces its lineage to the turn of the century, when its early form provided a pragmatic approach to structuring web applications in Java. The Apache Software Foundation accepted and fostered the project, emphasizing an open development model and formal release cycles. Over time, Struts evolved through two major generations:

  • Struts 1, the original line, established the core concepts of an ActionServlet-based front controller, a struts-config.xml configuration model, and action classes paired with form beans and JSP views.
  • Struts 2, a significant redesign that grew out of the WebWork project, introduced a more flexible architecture built around interceptors, an enriched action model, and the OGNL expression language. This generation shifted some of the configuration and wiring responsibilities, offering a more modular runtime and a richer set of extension points.

Each generation aimed to improve developer productivity, testing, and integration with other Java EE technologies, while preserving the recognizable MVC separation of concerns that gave Struts its enduring identity. The project has maintained active development within the open-source ecosystem, balancing steady maintenance with the need to adapt to evolving security, performance, and deployment landscapes. For historical context on the platform, see Struts 1 and Struts 2.

Security has been a persistent concern for enterprise frameworks like Struts. The ecosystem has experienced notable vulnerabilities over the years, prompting careful patching and configuration hardening in production environments. The most widely known incident involved a critical remote code execution vulnerability in 2017, which brought considerable attention to how legacy frameworks are patched and retired in large organizations. The incident underscored the importance of timely upgrades to supported versions, rigorous dependency management, and infrastructure controls to limit exposure—lessons that resonate broadly across all web frameworks. See discussions around CVE-2017-5638 and related advisories for more details, and note the role of major incidents in shaping modern security practices for open-source software.

Architecture and components

Apache Struts supports two related but distinct architectures corresponding to its two major generations:

  • Struts 1 architecture

    • Core components: The front controller is implemented by an ActionServlet, which delegates requests to Action classes. Navigation decisions and request processing are described in a configuration file, historically struts-config.xml.
    • Data handling and views: Form beans carry request data between the view and the controller, while JSPs (often with Struts tag libraries) render the user interface.
    • Lifecycle and flow: The framework emphasizes a predictable flow from request through action processing to a forwarding view, facilitating centralized control over navigation, validation, and business rules.
    • Configuration and extensibility: Customizable interceptors and plug-ins allow teams to tailor validation, error handling, and reuse across applications.

  • Struts 2 architecture

    • Core changes: A more modular, interceptor-driven design supersedes some of the older Struts 1 patterns. The framework uses a stack-based data model to expose data to views and a chain of interceptors to apply cross-cutting concerns consistently.
    • Action model and OGNL: Actions are plain Java objects extended with convenient base classes such as ActionSupport, with OGNL (Object-Graph Navigation Language) used to bind request parameters to properties.
    • Value stack and tags: The ValueStack mechanism provides a flexible way to expose data to the view layer, and the Struts 2 tag library (often used in JSPs) simplifies UI construction.
    • View technology: While JSP remains common, Struts 2 is designed to be adaptable to other view technologies, reflecting a broader trend in Java web development toward decoupled front ends.

Across both generations, Struts emphasizes a clean separation between business logic, request handling, and presentation, while offering a comprehensive set of features for form processing, validation, and navigation. Key concepts include the front controller pattern, action mappings, and a robust tag library for building user interfaces. See Model–View–Controller for the architectural pattern that underpins its approach, and Web application framework for the broader category in which Struts sits.

OGNL, a core expression language used in Struts 2, is a notable component for property access and data binding. See OGNL for background on how this language operates and why it matters in the Struts 2 workflow. The framework’s configuration and extension points are designed to accommodate enterprise-scale applications with long lifecycles, including custom validators, interceptors, and plug-ins.

Features and ecosystem

  • MVC-based design: Struts dissects an application into distinct concerns, with controllers handling flow, models representing data, and views rendering output.
  • Tag libraries and form handling: Struts provides a set of tags to simplify JSP development and a structured approach to form validation and error reporting.
  • Extensibility: The interceptor architecture in Struts 2 enables consistent application of security, logging, and other cross-cutting concerns.
  • Integration with Java EE: Struts sits atop the Java platform and interoperates with other Java technologies, including Java EE components and deployment in servlet containers and application servers.
  • Open-source governance: As an Apache project, Struts adheres to Apache’s development and release practices, emphasizing transparency, community contributions, and standard licensing under the Apache License 2.0.

In practice, many large organizations used Struts as a backbone for mission-critical web applications. The framework’s durability and configurability made it attractive in environments with complex validation rules, porting requirements, and long maintenance cycles. See Java EE for the broader platform context and Open-source software for governance and development models.

Security, risk, and maintenance

Security incidents related to Struts resources have highlighted the importance of timely patching and dependency management in enterprise software stacks. The 2017 remote code execution vulnerability, rooted in how some requests could be crafted to exploit limited deserialization and parsing pathways, demonstrated how even mature frameworks require vigilant security practices. The incident led many organizations to accelerate upgrades, implement strict change controls, and invest in better defense-in-depth controls. See CVE-2017-5638 and Equifax for connected real-world cases and the role of patch management in incident response.

Maintenance in the Struts ecosystem often involves balancing legacy systems with the need for modernization. While newer Java web frameworks and microservice-oriented approaches have gained ground, many enterprises continue to run Struts-based applications due to the cost and risk of rewriting large, tightly integrated systems. The Apache governance model emphasizes careful release management, long-term support for critical versions, and a community-driven approach to security advisories and feature updates.

Adoption and legacy

During its heyday, Struts was a standard tool in many enterprise stacks, especially in financial services, government, and large commercial platforms. Its longevity reflects the realities of software in production: systems built years or decades ago persist, and migrating them to newer frameworks involves substantial planning, data migration, and risk assessment. The Struts ecosystem remains relevant for understanding the evolution of Java web frameworks and the historical decisions that shaped later choices such as componentized architectures, dependency management, and security discipline in open-source projects.

See also