BPEL Processes Research Articles

S2O: A smart objects orchestrator framework based on the web of things

The Web of Things (WoT) is a new paradigm in which everyday objects are connected to the Internet using popular Web technologies. The smart things are abstracted into RESTful Web services to facilitate their manipulation. The composition of these objects within the same business process creates an automated, time-synchronized routine that can perform even the most complex tasks. BPEL is an orchestration language that defines the process responsible for coordinating the Web services involved. However, this language presents some limitations in this context. BPEL 2.0 does not support RESTful Web services; its specification is incompatible with this architectural style of services. Moreover, its temporal expressivity is insufficient to cover all the constraints that may arise when composing services. This work aims to adapt BPEL to the requirements of the WoT environment, enabling it to create processes that invoke the smart things in precise time intervals. The solution is to exploit one of BPEL's strengths: its extensibility. The BPEL specification is enriched with four activities that reflect the REST uniform interface. They include the necessary attributes to send the request to the target object and receive the response in convened format representation. Also, temporal attributes are added to BPEL elements to schedule their start, end, and duration of execution. The manual addition of these temporal values requires a verification of their accuracy. The BPEL process must be reviewed to ensure its validity before its execution. A temporal Petri Net is proposed to detect any conflicts or inconsistencies between BPEL activities. As a result, associating the formal model with the extension allows BPEL to orchestrate smart things represented by RESTful Web services according to a well-defined temporal scenario. They respect the REST constraints and provide the BPEL activities with temporal attributes for efficient time management. The approach can be applied in all application areas to create temporal scenarios.

An Empirical Study on Data Flow Bugs in Business Processes

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.

Evaluating the trustworthiness of BPEL processes based on data dependency and XBFG

Composite services implement value-added functionality by composing service components of various granularities. Trust is an important criterion to judge whether a composite service can behave as expected. There is a great need for a flexible trust evaluation method for composite services. In this paper, a data dependency-based trust evaluation approach for composite services is proposed. Firstly, we derive define-use pairs of variables to identify data dependency between service components in BPEL processes modelled by an extensible BPEL flow graph (XBFG); then, dependency links including both direct and indirect data dependencies are used to evaluate the trust of these service components; furthermore, on the basis of BPEL structure and XBFG, reduction rules are proposed to evaluate the global trust of BPEL processes. Experimental results demonstrate that the proposed approach is effective for the trust evaluation of BPEL composite services and stable with the growing number of service components in BPEL.

Evaluating the trustworthiness of BPEL processes based on data dependency and XBFG

Composite services implement value-added functionality by composing service components of various granularities. Trust is an important criterion to judge whether a composite service can behave as expected. There is a great need for a flexible trust evaluation method for composite services. In this paper, a data dependency-based trust evaluation approach for composite services is proposed. Firstly, we derive define-use pairs of variables to identify data dependency between service components in BPEL processes modelled by an extensible BPEL flow graph (XBFG); then, dependency links including both direct and indirect data dependencies are used to evaluate the trust of these service components; furthermore, on the basis of BPEL structure and XBFG, reduction rules are proposed to evaluate the global trust of BPEL processes. Experimental results demonstrate that the proposed approach is effective for the trust evaluation of BPEL composite services and stable with the growing number of service components in BPEL.

Detect and analyse the concurrent flaws of the BPEL process in a VPN-based approach

Detect and analyse the concurrent flaws of the BPEL process in a VPN-based approach

UniFlexView: A unified framework for consistent construction of BPMN and BPEL process views

SummaryProcess view technologies allow organizations to create different granularity levels of abstraction of their business processes, therefore enabling a more effective business process management, analysis, interoperation, and privacy controls. Existing research proposed view construction and abstraction techniques for block‐based (ie, BPEL) and graph‐based (ie, BPMN) process models. However, the existing techniques treat each type of the two types of models separately. Especially, this brings in challenges for achieving a consistent process view for a BPEL model that derives from a BPMN model. In this paper, we propose a unified framework, namely UniFlexView, for supporting automatic and consistent process view construction. With our framework, process modelers can use our proposed View Definition Language to specify their view construction requirements disregarding the types of process models. Our UniFlexView's system prototype has been developed as a proof of concept and demonstration of the usability and feasibility of our framework.

End-to-end information flow security for web services orchestration

Multi-party interactions in Web Service (WS) composition are hard to managed and difficult to design and verify, especially while end-to-end information flow security (IFS) must be respected. Usually, IFS is guaranteed for a data originator and ultimate recipient WS, however inter-organizational service compositions involve partners that do not necessarily share the same level of security, especially for data they do not generate nor process themselves. In this paper, we focus on the non-interference property and we present a correct-by-construction approach to build orchestrated WSs with multi-party interactions. A key ingredient of this approach is to present the system composition at an abstract level as a component-based model where the IFS verification and the system configuration are considered at early stage. When this configuration is validated, that is, no security leak is detected, we automatically generate orchestrator components that handle IFS. Afterwards, we generate accordingly BPEL processes where the IFS constraints are enforced as security WS-policies in the BPEL description of services. We develop a set of tools that automate the approach and we validate the effectiveness of our approach with well known Web service use cases.

The QoS analysis of web services composition based on Jackson queuing network

With the popularity of distributed computing and mobile internet, services composition has become a hot research in the field of service computing. The QoS of web services composition organised by BPEL is determined by the internal structure, the probability distribution in the variables value of BPEL process and the external factors such as the hardware and software processing capabilities of web servers and the load of web servers. At present, the generalised Petri nets, queuing Petri nets, Markov processes and stochastic process algebra model which are widely used and cannot have a comprehensive analysis in obtaining the actual performance of web services composition in internet environment. In this paper, a set of mapping rules are established to transform the internal and external factors which have impacts on the QoS of web services composition into Jackson queuing network, meanwhile, a set of performance indexes and their formula are given. Based on these performance indexes, we comprehensively analyse the performance of web services composition and locate the bottleneck of web services composition when the internal and external factors are changed so that, the performance of web services composition can be predicted before its deployment.

An Approach Based on Hierarchical Petri Nets for the Verification of Interconnected BPEL Processes

This article describes an MDE approach for transformation from BPEL specifications to WF-nets models for verifying behavioral properties on IOWF (Inter-Organizational Workflow) processes. The authors consider WF processes specified with BPEL and interconnected together according to specific cooperation patterns. They define a specific class of Petri nets called Hierarchical WF-nets (HWN) in order to formally check the “soundness” property on IOWF process models. For that, their verification approach is defined around three main phases: (i) recovery of the BPEL file(s) and generation of process tree(s), (ii) transformation from BPEL to WF-nets (resp. HWN) models using mapping and transformation rules and (iii) verification of the “soundness” property on the models obtained. They particularly define and implement a set of specific transformation rules which are closely linked to the interconnection rules attached to each cooperation pattern. Also, to show the feasibility of their verification method, the authors developed a “WF-Checking” tool which allows the implementation and testing of the proposed approach.

Специфікація процесу семантичної анотації Веб-сервісів

The complexity of the tasks solved with web services does not allow to limit their consideration to a functional model, but also requires the consideration of behavioral aspects of web services. To provide the possibility of automated resolving web services tasks, first, it is necessary to semantify their description using computer-friendly tools for formal definition. Web service that is not enriched with semantics, does not allow you to understand what it does. Semantization consists in expanding the description of the web service with clear and understandable semantic annotations that should cover all important functional and non-functional aspects of the service, but do not overload it with redundant information. This explains the relevance of the problem of the specification of the annotation process itself, taking into account the definition of the semantization goal, the main aspects of annotating the service, the sources of the information, the semantics categories, and the process steps providing the annotated specification of the service, with further conversion - transformation into a machine-processed form. It is the subject of this paper. The main stages of the process correspond to the categories of semantics defined in the annotation. Inputs, outputs, information sources and implementation steps are specified for each stage. Besides special attention is paid to define the place of descriptive logic in the process of semantizing the web service. Descriptive logic is considered as a formal tool for the semantic description of the service, which makes it possible to verify the correctness of the service’s definition and it allows logical inference when solving Web services tasks, etc. It is given an example of an extension of a fragment of BPEL process with ontological semantic anotations. In this case, the semantization consists in choosing suitable domain ontologies and establishing links between ontology concepts represented by the means of the descriptive logic and metadata describing the functionality of the web service. The annotated system of transition states (ASTS) is the computer- understandable service presentation model. This is due to the fact that, in particular, most of the AI planning systems work with STS, the mechanisms of which can also be used to automatically solve web service tasks. Problems in programming 2018; 2-3: 204-213

Opening web applications for third-party development: a service-oriented solution

Web applications are nowadays prevalent software systems in our everyday's life. A lot of these applications have been developed for end users only. Thus, they are not designed by considering future extensions that would be developed by third parties. One possible and interesting solution for opening these applications for such kind of extension development is to create and deploy Web services starting from these applications. In this paper, we present a method and a tool for semiautomatically creating Web service implementations from applications having Web interfaces. The proposed method generates operations that are published in Web services for each functionality provided by a Web application. In addition, it generates new operations starting from Web interfaces. Our approach goes further in the creation of services by generating executable orchestrations, as BPEL processes, starting from navigations in the Web interfaces of these applications and by providing BPMN choreography specifications starting from the collaborations between the generated Web services. We implemented and experimented our solution in the migration of three real-world Web applications toward Web service-oriented systems.

OaaS Based on Temporal Partitioning with Minimum Energy Consumption

Cloud computing is an economical solution for industry which is highly scalable and useful of virtualized resources that can be used on demand. It will have a significant impact on companies with the introduction of orchestration platforms as a Service (OaaS) to perform the services that support a variety of business processes such as BPEL. It's becoming an adoptable technology for many of the organizations, thanks to its flexibility and because it reduces total cost of ownership. Thus, an effective OaaS must meet several requests simultaneously; ensuring scalability and optimizing the use of shared resources in order to minimize energy consumption. In this paper, we will investigate three issues i) exploiting the minimum of resources to execute a maximum number of processes, ii) Preventing possible overload to the server, and iii) minimizing dynamic energy consumption which becomes one of the main challenges for large-scale computing, such as in cloud data center. As a solution for these challenges, we propose to use Workflow partitioning technique and this based on temporal dynamic reconfiguration approach. Our work aims to reduce the dynamic energy consumption; especially in communication buffers between partitions of BPEL process during partitioning. The proposed approach is based on two main steps: 1) Estimate the energy consumption of BPEL processes 2) Temporal and dynamic partitioning of BPEL process based on reconfigurable architecture in order to minimize overall energy consumption on each BPEL process.

CTL Model Checking of Web Services Composition based on Open Workflow Nets Modeling

Web services composition (WSC) has an enormous potential for the organizations in the B2B area. In fact, different services collaborate through the exchange of messages to implement complex business processes. BPEL is one of the most used languages to develop such cooperation. However, it has been proved that its use is complex and can require some expertise in XML syntax. Even its graphical representation is not evident to handle. This is why the authors propose to model Web services using oWF-nets, a subclass of Petri nets, and then, to translate them to BPEL. Whilst, a WSC is with added value only if the involved services are compatible. So in this context, across the translation proposed the researchers develop a verification layer of the WSC compatibility. Hence, they propose a framework named D&A4WSC which allows to model the WSC by oWF-nets, to check their compatibility with the model checker NuSMV and to translate them if they are compatible in BPEL processes using the oWFN2BPEL compiler. D&A4WSC permits, furthermore, to formally analyze a BPEL process.

Path Feasibility Analysis of BPEL Processes under Dead Path Elimination Semantics

Path Feasibility Analysis of BPEL Processes under Dead Path Elimination Semantics

Integrating quality requirements in engineering web service orchestrations

Today’s Web services are considered as one of the leading technologies for implementing components of service-oriented software architectures for desktop, Web or mobile applications. When designing workflows of activities that involve the invocation of these Web Services, we build either orchestrations or choreographies. The engineering of such applications is an emerging research topic with many challenges. Among them, we can stress out the crucial question of how to answer quality requirements in such engineering processes. This paper, presents a method which aims at assisting software architects of Web Service orchestrations in integrating quality requirements in their artifacts. In order to satisfy a quality requirement, this method suggests a list of service-oriented patterns. We base our work on the postulate stating that quality can be implemented through patterns, which can be specified with checkable/processable languages. This method helps architects to reach concrete architecture changes that can be automatically performed on the orchestration in order to apply a pattern, and thus integrate its associated quality. We experimented our method on a set of real-world orchestrations (BPEL processes) to measure the overhead of using it in engineering such service-oriented applications. The obtained results showed that our method brings a significant gain of time.

A New Formal Modeling Method for Web Service Composition

With the rapid development of e-commerce, the application of web service composition is becoming increasingly important in many areas. If we apply unchecked web service composition, then we can only discover problems afterwards, and we have to devote unnecessary energy to repair. Here, formal modeling serves to be a premise to check. This paper brings up a formal modeling method for web service composition based on BDL (behavioral description language). The structure of this essay is to analyze the description of BPEL process, and we can get the formal model from the BPEL-to-BDL mapping relation.

AOMD approach for context-adaptable and conflict-free Web services composition

BPEL or Business Process Execution Language is so far the most important standard language for effective composition of Web services. However, like most available process orchestration engines, BPEL does not provide automated support for reacting according to many changes that are likely to arise in any Web services composition, like downtime services, modifications in the business logic or even new policies to govern the composition. Also low-level specification of these new changes, which would be integrated at runtime in the BPEL process, will be far from being used conveniently. Moreover, the complexity of interaction in composite Web services and the diversity of rules and policies can lead to critical behavioral conflicts. We propose in this paper AOMD, a novel aspect-oriented and model driven approach that defines new grammar to address both adaptability and behavioral conflicts problems, and offers extension for WS-BPEL meta-model for high level specification of aspects. Further, we formally verify our proposition and we present real life case study, examples and experimental results that demonstrate the feasibility and effectiveness of our work.

Privacy Data Analysis in Services Combination Process Based on CPN

BPEL is a Business Process Execution Language, BPEL process complish the cooperation of Web services through exchanging messages between services. Some privacy data should be collected and exposed in BPEL process, the leaking of privacy data will bring troubles to the user of Web service. So the paper’s aim is analyzing and verifying whether the usage or the transmission of privacy data in BPEL process violate the privacy statute. This paper establishs a BPEL CPN model using modeling method and uses extended P3P policy to describe user’s requirements, finally a prototype system is designed and developed. The result of the experiment can show whether the usage or the transmission of privacy data in BPEL violate the privacy statute and can show the default informations in detail.

Exception Throwing Analysis and Exception Handling Method for BPEL

Business developer needs to develop fault-tolerant process, but fault-tolerant process development based on exception handling mechanism provided by BPEL costs much time and is easy to make mistake. We analyze application exception throw chain theory of service-oriented system. Exception throwing of BPEL process is broadcasted among component layer, service layer and process layer. We also propose an application exception handling method for BPEL by using EHPDL-P. EHPDL-P can separate normal business logic and exception business logic, and thus it can enhance BPEL fault-tolerance ability.

An Empirical Analysis of Business Process Execution Language Usage

The current state of executable business process languages allows for and demands optimization of design practices and specifications. In this paper, we present the first empirical study that analyses Web Services Business Process Execution Language (WS-BPEL or BPEL) usage and characteristics of real world executable business processes. We have analysed 1,145 BPEL processes by measuring activity usage and process complexity. In addition, we investigated the occurrence of activity usage patterns. The results revealed that the usage frequency of BPEL activities varies and that some activities have a strong co-occurrence. BPEL activities often appear in activity patterns that are repeated in multiple processes. Furthermore, the current process complexity metrics have proved to be inadequate for measuring BPEL process complexity. The empirical results provide fundamental knowledge on how BPEL specification and process design practices can be improved. We propose BPEL design guidelines and BPEL language improvements for the design of more understandable and less complex processes. The results are of interest to business process language designers, business process tool developers, business process designers and developers, and software engineering researchers, and contribute to the general understanding of BPEL and service-oriented architecture.