Synthesizing Glue Operators from Glue Constraints for the Construction of Component-Based Systems
We study glue operators used in component-based frameworks to obtain systems as the composition of atomic components described as labeled transition systems (LTS). Glue operators map tuples of LTS into LTS. They restrict the behavior of their arguments by performing memoryless coordination. In a previous paper, we have proposed a simple format for SOS rules that captures, in particular, glue operators from known frameworks such as CCS, SCCS, CSP, and BIP. This paper studies a new way for characterizing glue operators: as boolean glue constraints between interactions (sets of ports) and the state of the coordinated components. We provide an SOS format for glue, which allows a natural correspondence between glue operators and glue constraints. This correspondence is used for automated synthesis of glue operators implementing given glue constraints. By focusing on the properties that do not bear computation, we reduce a very hard (and, in general, undecidable) problem of synthesizing controllers to a tractable one. The examples in the paper show that such properties are natural and can be expressed as glue constraints in a straightforward manner. Finally, we compare expressiveness of the proposed formalisms with the glue used in the BIP framework and discuss possible applications.