In this paper, we present a framework which incorporates runtime adaptation for BPEL scenarios. The adaptation is based on (a) the quality of service parameters of available services, allowing for ...tailoring their execution to the diverse needs of individual users and (b) collaborative filtering techniques, allowing clients to further refine the adaptation process by considering service selections made by other clients, in the context of the same business processes. The proposed framework also caters maintaining the transactional semantics that invocations to multiple services offered by the same provider may bear.
•We present an algorithm combining QoS and collaborative filtering for BPEL adaptation.•The combination introduces collaborating filtering functionality maintaining high QoS.•We exploit the sparsity of the rating matrix to tackle known issues of CF.•We evaluate the approach both in terms of performance and adaptation QoS.
•A novel approach is provided to specify and verify service compositions contracts.•BPEL is extended to represent specifications and mark the points to be verified.•Properties are derived ...automatically from composition implementations.•The verification process relies on commitment logic and its model checking.•Web services are verified from the perspectives of compliance and violations.
The paper proposes a novel model checking-based approach towards verifying the compliance of intelligent agent-based web services with contracts regulating their compositions specified in the Business Process Execution Language (BPEL). Unlike the existing approaches in the literature, the main contribution and impact of the introduced approach is the ability to verify intelligent and autonomous composite web services by capturing and describing in details both compliance and violation behaviors, how the system can distinguish between them, and how the system reacts and can be recovered after each violation. The approach encompasses three contributing parts, namely: 1) the marking process of an extended BPEL; 2) the transformation of the extended and marked BPEL to an automata model; and 3) the encoding of the resulting automata model into the Interpreted Systems Programming Language (ISPL), the input language of the MCMAS model checker for intelligent and autonomous multi-agent systems. In the first part, we extend BPEL that specifies the business process of the composition by creating custom activities called labels. We use those labels as means to represent the specifications and mark the points the developer aims to verify. A significant advantage of this labeling is the ability to highlight specific points in the design to be verified and to distinguish compliance behaviors from violations, which makes this verification focused and highly efficient. In the second part, we introduce new transformation rules to transform the extended and marked BPEL to an automata model. This transformation requires a prior modeling of agent-based web services composition using automata definitions. In the third part, we introduce algorithmic translation rules encoding the resulting automata model into ISPL. This translation makes model checking the behavior of our contract-driven compositions possible. A novel characteristic of the proposed approach is the automatic generation of the properties against which the system is verified from the composition’s implementation, which is technically challenging. The verification properties are expressed in the Computation Tree Logic of Commitments (CTLC). Technically, CTLC provides a powerful representation to formally model 1) interactions among multi-agent based web services and 2) compliance and violation behaviors within composite business contracts by making use of communicative commitment operators. CTLC also includes a fulfillment operator which helps formally check the compliance with business contracts and specify the system recovery. A detailed case study from expert and intelligent systems domain along with experimental results are also reported in the paper. Finally, the main impact and significance of the paper on expert and intelligent systems is the ability to use these systems safely since there is a way to verify if the intelligent components behave according to and in compliance with the underlying regulating contracts.
With the popularity of Web Services and Service-Oriented Architecture (SOA), quality assurance of SOA applications, such as testing, has become a research focus. Programs implemented by the Business ...Process Execution Language for Web Services (WS-BPEL), which can be used to compose partner Web Services into composite Web Services, are one popular kind of SOA applications. The unique features of WS-BPEL programs bring new challenges into testing. A test case for testing a WS-BPEL program is a sequence of messages that can be received by the WS-BPEL program under test. Previous research has not studied the challenges of message-sequence generation induced by unique features of WS-BPEL as a new language. In this paper, we present a novel methodology to generate effective message sequences for testing WS-BPEL programs. To capture the order relationship in a message sequence and the constraints on correlated messages imposed by WS-BPEL's routing mechanism, we model the WS-BPEL program under test as a message-sequence graph (MSG), and generate message sequences based on MSG. We performed experiments for our method and two other techniques with six WS-BPEL programs. The results show that the message sequences generated by using our method can effectively expose faults in the WS-BPEL programs.
An increasing number of service-based business processes are being developed with the booming of BPaaS (Business Process as a Service) in cloud computing. The profits and performance of enterprises ...strongly depend on the soundness of their processes being bereft of control flow and data flow bugs. Although some work has focused on the detection of control flow bugs, few studies have comprehensively and empirically investigated data flow bugs in business processes. To this end, we report an empirical study on data flow bugs in business (BPEL) processes. Our analysis of 178 real-world BPEL processes reveals that data flow bugs are surprisingly common: 94 BPEL processes involve data flow bugs, among which redundant output is predominant. The distribution and common scenarios of data flow bugs provide a reference for BPEL process designers. We also investigate the correlation between process complexity metrics and data flow bugs. Based on the statistics of the process complexity metrics and data flow bugs in our empirical study, we present a method to select appropriate metrics as features of BPEL processes and utilize state-of-the-art supervised learning algorithms to predict data flow bugs in an unseen BPEL process. The prediction accuracies of the different classification algorithms exceed 90 percent on average when using our selected metrics.
•Our paper proposes a formal method for compatibility and consistency checking of WS-BPEL orchestrations of composite OWL-S Web services.•We first translate OWL-S and BPEL descriptions into ...communicating automata. Our technique then extends these automata with erroneous states and combines them.•It uses the global synchronization automaton for deadlock and error detection by checking the persistence of erroneous states, which means presence of incompatibilities in the interaction protocol of combined services.•We deal also with the consistency checking of the composite application against its choreography considered as a requirement specification.•This verification phase covers the signatures matching as well as conformance of the interaction protocols.
Web service orchestrations aim at offering value-added services that meet the increasing complex requirements of business processes. Since it becomes harder to manually check the correctness of such systems, we propose a formal method for their consistency checking by first translating OWL-S composite services and WS-BPEL orchestrator into communicating automata using an iterative process driven by control structures of these languages. Thereafter, we build the synchronization product of the resulting automata and proceed to its compatibility checking in order to unveil forbidden states, which depict incompatibilities in that orchestration interaction protocol. Last, this automaton consistency is checked against the behavioral model of WS-CDL choreography seen as its specification to which it has to conform.
Automatic Web Service composition is gaining momentum as the potential silver bullet in Service Oriented Architecture. The need for interservice compatibility analysis and indirect composition has ...gone beyond what the existing service composition/verification technologies can handle. Given two services whose interface invocation constraints are described by a Web Services-Business Process Execution Language (WS-BPEL or BPEL), we analyze their compatibility and adopt mediation as a lightweight approach to make them compatible without changing their internal logic. We first transform a BPEL description into a service workflow net, which is a kind of colored Petri net (CPN). Based on this formalism, we analyze the compatibility of two services, and then devise an approach to check whether there exists any message mediator so that their composition does not violate the constraints imposed by either side. The method for mediator generation is finally proposed to assist the automatic composition of partially compatible services. Our approach is validated through a real-life case and further research directions are pointed out.
Querying business processes with BP-QL Beeri, Catriel; Eyal, Anat; Kamenkovich, Simon ...
Information systems (Oxford),
09/2008, Letnik:
33, Številka:
6
Journal Article
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We present in this paper BP-QL, a novel query language for querying business processes. The BP-QL language is based on an intuitive model of business processes, an abstraction of the emerging BPEL ...(business process execution language) standard. It allows users to query business processes visually, in a manner very analogous to how such processes are typically specified, and can be employed in a distributed setting, where process components may be provided by distinct providers.
We describe here the query language as well as its underlying formal model. We consider the properties of the various language components and explain how they influenced the language design. In particular we distinguish features that can be efficiently supported, and those that incur a prohibitively high cost, or cannot be computed at all. We also present our implementation which complies with real life standards for business process specifications, XML, and Web services, and is used in the BP-QL system.
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