Session Communication and Integration

The scenario-based specification of a large distributed system is usually naturally decomposed into various modules. The integration of specification modules contrasts to the parallel composition of program components, and includes various ways such as scenario concatenation, choice, and nesting. The recent development of multiparty session types for process calculi provides useful techniques to accommodate the protocol modularisation, by encoding fragments of communication protocols in the usage of private channels for a class of agents. In this paper, we extend forgoing session type theories by enhancing the session integration mechanism. More specifically, we propose a novel synchronous multiparty session type theory, in which sessions are separated into the communicating and integrating levels. Communicating sessions record the message-based communications between multiple agents, whilst integrating sessions describe the integration of communicating ones. A two-level session type system is developed for pi-calculus with syntactic primitives for session establishment, and several key properties of the type system are studied. Applying the theory to system description, we show that a channel safety property and a session conformance property can be analysed. Also, to improve the utility of the theory, a process slicing method is used to help identify the violated sessions in the type checking.Comment: A short version of this paper is submitted for revie

Semantic Analysis of Component-aspect Dynamism for Connector-based Architecture Styles

Architecture Description Languages usually specify software architectures in the levels of types and instances. Components instantiate component types by parameterization and type conformance. Behavioral analysis of dynamic architectures needs to deal with the uncertainty of actual configurations of components, even if the type-level architectural descriptions are explicitly provided. This paper addresses this verification difficulty for connector-based architecture styles, in which all communication channels of a system are between components and a connector. The contribution of this paper is two-fold: (1) We propose a process-algebraic model, in which the main architectural concepts (such as component type and component conformance) and several fundamental architectural properties (i.e.~deadlock-freedom, non-starvation, conservation, and completeness) are formulated. (2) We demonstrate that the state space of verification of these properties can be reduced from the entire universe of possible configurations to specific configurations that are fixed according to the type-level architectural descriptions. © 2012 IEEE