Complex Services Availability in Service Oriented Systems

The aim of the paper is to discuss some issues related to services composition in service oriented systems based on Service Oriented Architecture (SOA) paradigm. The main feature of service oriented architecture is that the required services may be efficiently and flexibly composed of available well-defined components providing certain functionalities. It is rather obvious that the flexibility and availability of complex services, composed of commonly-shared components, may be limited in environment where concurrent requests should be satisfied. In gain to discuss complex services availability as dependent on components availabilities and complex service structure a model of complex service is introduced. The latter is used to discuss various aspects of service availability in context of service structure and components availabilities changes.