Abstract
During the last several years, we have established the symmetric active/active replication model for service-level high availability and implemented several proof-of-concept prototypes. One major deficiency of our model is its inability to deal with dependent services, since its original architecture is based on the client-service model. This paper extends our model to dependent services using its already existing mechanisms and features. The presented concept is based on the idea that a service may also be a client of another service, and multiple services may be clients of each other. A high-level abstraction is used to illustrate dependencies between clients and services, and to decompose dependencies between services into respective client-service dependencies. This abstraction may be used for providing high availability in distributed computing systems with complex service-oriented architectures.
