Hera

Preface

Introduction Building extensible architectures nowadays is a core principle to create maintainable applications. This is why fully fledged plugin environments like OSGi are so poular these days. Unfortunately the introduction of OSGi introduces a lot of complexity to projects. Hera provides a more pragmatic approach to plugin development by providing the core flexibility of having plugin implementations extending a core system's functionality but of course not delivering core OSGi features like dynamic class loading or runtime installation and deployment of plugins. Although Hera thus is not nearly as powerful as OSGi, it servers little man's requirements to build a modular extensible application.

Context You want to build an extensible architecture minimizing overhead as much as possible You cannot use OSGi as fully fledged plugin architecture for whatever reasons You want to express extensibility by providing dedicated plugin interfaces You want to extend the core system by simply providing an implementation of the plugin interface bundled in a JAR file and available in the classpath. (You use Spring in your application) The last point actually is not essential although Hera gains a lot of momentum in collaborative use with Spring.

Technologies Spring Spring is the defacto standard application framework for Java applications. Its consistent programming model, easy configuration and wide support for all kinds of third party libraries makes it the first class citizen of application frameworks. Hera tightly integrates into Spring's component model and extends the core container with some custom functionality.