Composition of Web services is much studied to support business-to-business and enterprise application integration in e-commerce. Current Web service composition approaches range from practical languages aspiring to become standards (like BPEL, WS-CDL, OWL-S and WSMO) to theoretical models (like automata, Petri nets and process algebras). In this paper we compare these approaches w.r.t. a selected set of characteristics (like trust, security and performance) and we advocate the use of formal models, and their tool support, to increase one's confidence in web service compositions. This paper can assist web service composition designers and developers to deliver lasting solutions, in concordance with the technology's critical needs.

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Web Service Composition Approaches: From Industrial Standards to Formal Methods

Information systems have to respond well to the changing business environment. Thus, they must have architecture which withstands the change. To design such systems, business process modeling is effective, however, the models include often abstractness and arbitrariness. Therefore, there have been efforts that validate rigorousness of the models. They have defined semantics of the models and applied various logics and formal methods to verification of the rigorousness. This paper focuses on formal verification of the models and surveys the efforts. We also discuss the prospect of the solutions. The establishment of the verification will be surely helpful toward solving the problems on business process reengineering, business process management, service-oriented architecture, and so on.

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A Survey of Formal Verification for Business Process Modeling

Recently, the temporal constraint satisfiability is regarded as an important criterion in Web service composition to guarantee its timely completion. This leads to a new challenge in analyzing the compatibility of Web services under temporal constraints. The existing methods either do not consider message mismatches between services in a composition or suffer from state-space explosion by verifying a service composition model as a whole; or lack the ability to generate execution paths of each participating service. In this paper, we present a Petri net-based method to address these three issues in a holistic manner, and also in a modular way. Compared with the existing work, the proposed approach not only composes Web services by adding a mediation net to deal with message mismatches, but also checks the compatibility w.r.t. temporal constraints by generating modular timed state graphs. Furthermore, the reliable and usable execution paths that satisfy the timed compatibility can be derived to guide service execution and avoid any temporal exception.

Timed Compatibility Analysis of Web Service Composition: A Modular Approach Based on Petri Nets

Grid computing is the federation of resources from multiple locations to facilitate resource sharing and problem solving over the Internet. The challenge of finding services or resources in Grid environments has recently been the subject of many papers and researches. These researches and papers evaluate their approaches only by simulation and experiments. Therefore, it is possible that some part of the state space of the problem is not analyzed and checked well. To overcome this defect, model checking as an automatic technique for the verification of the systems is a suitable solution. In this paper, an adopted type of resource discovery approach to address multi-attribute and range queries has been presented. Unlike the papers in this scope, this paper decouple resource discovery behavior model to data gathering, discovery and control behavior. Also it facilitates the mapping process between three behaviors by means of the formal verification approach based on Binary Decision Diagram (BDD). The formal approach extracts the expected properties of resource discovery approach from control behavior in the form of CTL and LTL temporal logic formulas, and verifies the properties in data gathering and discovery behaviors comprehensively. Moreover, analyzing and evaluating the logical problems such as soundness, completeness, and consistency of the considered resource discovery approach is provided. To implement the behavior models of resource discovery approach the ArgoUML tool and the NuSMV model checker are employed. The results show that the adopted resource discovery approach can discovers multi-attribute and range queries very fast and detects logical problems such as soundness, completeness, and consistency.

Behavioral modeling and formal verification of a resource discovery approach in Grid computing

In this paper we show how we can translate Web Services described by WS-CDL into a timed automata orchestration, and more specifically we are interested in Web services with time restrictions. Our starting point are Web Services descriptions written in WSBPEL- WSCDL (XML-based description languages). These descriptions are then automatically translated into timed automata, and then, we use a well known tool that supports this formalism (UPPAAL) to simulate and analyse the system behaviour. As illustration we take a particular case study, an airline ticket reservation system.

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Automatic translation of WS-CDL choreographies to timed automata

Verification of Web Services with Timed Automata

In previous work we have presented the generation of WS-CDL and WS-BPEL documents. In this paper we show the unification of both generations. The aim is to generate correct WS-BPEL skeleton documents from WS-CDL documents by using the Timed Automata as an intermediary model in order to check the correctness of the generated Web Services with Model Checking Techniques. The model checker used is UPPAAL, a well known tool in theoretical and industrial cases that performs the verification and validation of Timed Automata. Note that our interest is focused on Web services where the time constraints play a critical role.

Automatic generation of Correct Web Services Choreographies and Orchestrations with Model Checking Techniques

In this paper we show how we can use a classical UML diagram, the sequence diagram, for the description of business process behavior based on Web services with time constraints. More specifically, we see how these diagrams can capture the main elements of the Web services business process execution language (WS-BPEL), and then, how we can translate these diagrams into Web services business process execution language.

Using UML Diagrams to Model Real-Time Web Services

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María-Emilia Cambronero

Papers

Automatic translation of WS-CDL choreographies to timed automata

Verification of Web Services with Timed Automata

Automatic generation of Correct Web Services Choreographies and Orchestrations with Model Checking Techniques

Using UML Diagrams to Model Real-Time Web Services

Model Checking Techniques applied to the design of Web Services