Components, Contracts and Vocabularies - Making Dynamic Component Assemblies more Predictable.

Abstract

In recent years, dynamic component-based systems such as OSGi and its derivatives have become very successful. This has created new challenges for verification. Assemblies are created and modified dynamically at runtime, but many existing techniques such as unit testing are designed for buildtime verification. Runtime verification is usually restricted to type checks. We propose a simple component contract language that is powerful enough to represent different types of complex contracts between collaborating components, including contracts with respect to component semantics and quality of service attributes, and contracts that refer to resources other than programing language artefacts. These contracts are based on a pluggable contract vocabulary and can then be used for runtime verification of assemblies. We present a proof of concept implementation of the contract language proposed for the OSGi/Eclipse component model.

API Evolution and Compatibility: A Data Corpus and Tool Evaluation.

“…Even component meta data may be part of contracts that determines compatibility, consider for instance issues around the compatibility of open sources licenses [31]. While most component systems used in industry focus on the API aspect of compatibility, non-functional aspects have been investigated and considered by several authors [9], and led to several (often OSGi-based) implementations, including, Fractal [6], Sofa [36] and Treaty [15]. Semantic contracts can be expressed by using pre-and post-conditions in the tradition of Hoare Logic [23] and design by contract [30].…”