Heterogeneous Queueing Networks with Blocking: An Architectural Approach based on SPA

Queueing networks (QNs) with finite capacity queues and blocking can be applied for performance analysis and evaluation of computer and communication systems with finite capacity resources and population constraints. Heterogeneous QNs with blocking model systems where components have different blocking policies or mechanisms. Performance analysis and functional verification, e.g. deadlock freedom, of heterogeneous QNs are in general difficult. We propose a framework for combined functional and performance analysis of heterogenous QNs with finite capacity and blocking based on an architectural description language (ADL) relying on stochastic process algebra (SPA). First, we define a library of parametrized models of finite capacity queue service centers supporting certain blocking mechanisms, as they are the basic building blocks of the QNs with blocking. This is done with Æmilia, an ADL for assembling in a controlled way the SPA descriptions of the behavior of the components of the service centers. Then, we construct Æmilia models of heterogeneous QNs with blocking by simply composing the basic QN building blocks described with Æmilia. Functional properties, such as deadlock freedom, can be automatically verified on the Æmilia models of the heterogeneous QNs with blocking. Likewise, the Markov chains underlying the heterogeneous QNs with blocking can be automatically derived from their Æmilia models. Moreover, we can easily define new and different blocking policies in a heterogeneous QN by providing the related Æmilia descriptions that can be compositionally integrated in the QN model and analyzed by the proposed approach.