Preserving distributed systems critical properties: a model-driven approach

The need for creating predictability in distributed systems is most often specified in terms of quality-of-service (QoS) requirements, which help define the acceptable levels of dependability with which capabilities such as processing capacity, data throughput, or service availability reach users. For longer-term properties such as scalability, maintainability, adaptability, and system security, we can similarly use persistent software attributes (PSAs) to specify how and to what degree such properties must remain intact as a network expands and evolves over time. The Skoll distributed continuous software quality assurance process helps to identify viable system and software configurations for meeting stringent QOS and PSA requirements by coordinating the use of distributed computing resources. The authors tested their process using the large, rapidly evolving ACE+TAO middleware suite.