Executable Interface Specifications for Testing Asynchronous Creol Components

Abstract

Creol is a high-level, object-oriented language for distributed systems, featuring active objects and asynchronous method calls. In this paper we present a behavioral interface specification language over communication trace labels to specify components in terms of traces of observable behavior. In the specification, a clean separation of concerns between interaction under the control of the component or coming from the environment is central, which leads to an assumption-commitment style description of a component's behavior. The assumptions schedule the order of inputs, whereas the outputs as commitments are being tested for conformance. To ensure the mentioned separation of responsibilities, we define wellformedness conditions which in addition assure that only "meaningful" traces, i.e., those corresponding to actual behavior, can be specified. The specification language is characterized by two other salient features: it allows to specify freshness of communicated values and furthermore, it respects the asynchronous nature of communication in Creol: the output is tested only up-to an appropriate notion of observability.

Delta-Oriented Monitor Specification

“…An interface behaviour specification language for the actor-language Creol was proposed in [8]. It is a regular language over constructor-and method invocations with variable bindings, which only supports matching of bound object-identities.…”

Asynchronous Learning for Service Composition

“…Grabe et al [10] develop a technique for testing asynchronous black-box components, by using an executable interface specification. Their method addresses the difference between interacting under component control or under environment control, by describing the component behaviour in an assumptioncommitment style.…”

A Framework for Reasoning on Component Composition

“…Active objects in Creol have asynchronous communication by method calls and futures. Creol also offers components; the paper [12] presents a framework for component description and test. A simple specification language over communication labels is used to enable the expression of the behaviour of a component as a set of traces at the interfaces.…”