Component Contracts in Service-Oriented Architectures

For SOAs to reach their full potential, the basic interoperable framework must accommodate meaningful quality-of-service contracts. Work on both industry-specific standards and semantic Web services is still needed to fully meet that goal. At the core of service-oriented architectures (SOAs) are distributed software components provided or accessed by independent third parties. Because access is not limited to a specific organization, explicit component contracts and universally adopted standards must support third-party access. Although such contracts could cover any technical or business aspect of service interaction, the current focus is on quality-of-service (QoS) policies. From an SOA point of view, we must consider two separate aspects of the use of QoS policies: interoperability between components, which is the subject of the Web services specifications stack; and composition, which composition models, such as the service component architecture (SCA).