Reo + mCRL2: A Framework for Model-checking Dataflow in Service Compositions

The paradigm of service-oriented computing revolutionized the field of software engineering. According to this paradigm, new systems are composed of existing stand-alone services to support complex cross-organizational business processes. Correct communication of these services is not possible without a proper coordination mechanism. The Reo coordination language is a channel-based modeling language that introduces various types of channels and their composition rules. By composing Reo channels, one can specify Reo connectors that realize arbitrary complex behavioral protocols. Several formalisms have been introduced to give semantics to Reo. In their most basic form, they reflect service synchronization and dataflow constraints imposed by connectors. To ensure that the composed system behaves as intended, we need a wide range of automated verification tools to assist service composition designers. In this paper, we present our framework for the verification of Reo using the toolset. We unify our previous work on mapping various semantic models for Reo, namely, constraint automata, timed constraint automata, coloring semantics and the newly developed action constraint automata, to the process algebraic specification language of , address the correctness of this mapping, discuss tool support, and present a detailed example that illustrates the use of Reo empowered with for the analysis of dataflow in service-based process models

Reo + mCRL2: A Framework for Model-Checking Dataflow in Service Compositions

The paradigm of service-oriented computing revolutionized the field of software engineering. According to this paradigm, new systems are composed of existing stand-alone services to support complex cross-organizational business processes. Correct communication of these services is not possible without a proper coordination mechanism. The Reo coordination language is a channel-based modeling language that introduces various types of channels and their composition rules. By composing Reo channels, one can specify Reo connectors that realize arbitrary complex behavioral protocols. Several formalisms have been introduced to give semantics to Reo. In their most basic form, they reflect service synchronization and dataflow constraints imposed by connectors. To ensure that the composed system behaves as intended, we need a wide range of automated verification tools to assist service composition designers. In this paper, we present our framework for the verification of Reo using the mCRL2 toolset. We unify our previous work on mapping various semantic models for Reo, namely, constraint automata, timed constraint automata, coloring semantics and the newly developed action constraint automata, to the process algebraic specification language of mCRL2, address the correctness of this mapping, discuss tool support, and present a detailed example that illustrates the use of Reo empowered with mCRL2 for the analysis of dataflow in service-based process models

Ontology based contextualization and context constraints management in web service processes

The flexibility and dynamism of service-based applications impose shifting the validation process to runtime; therefore, runtime monitoring of dynamic features attached to service-based systems is becoming an important direction of research that motivated the definition of our work. We propose an ontology based contextualization and a framework and techniques for managing context constraints in a Web service process for dynamic requirements validation monitoring at process runtime. Firstly, we propose an approach to define and model dynamic service context attached to composition and execution of services in a service process at run-time. Secondly, managing context constraints are defined in a framework, which has three main processes for context manipulation and reasoning, context constraints generation, and dynamic instrumentation and validation monitoring of context constraints. The dynamic requirements attached to service composition and execution are generated as context constraints. The dynamic service context modeling is investigated based on empirical analysis of application scenarios in the classical business domain and analysing previous models in the literature. The orientation of context aspects in a general context taxonomy is considered important. The Ontology Web Language (OWL) has many merits on formalising dynamic service context such as shared conceptualization, logical language support for composition and reasoning, XML based interoperability, etc. XML-based constraint representation is compatible with Web service technologies. The analysis of complementary case study scenarios and expert opinions through a survey illustrate the validity and completeness of our context model. The proposed techniques for context manipulation, context constraints generation, instrumentation and validation monitoring are investigated through a set of experiments from an empirical evaluation. The analytical evaluation is also used to evaluate algorithms. Our contributions and evaluation results provide a further step towards developing a highly automated dynamic requirements management system for service processes at process run-time

Transforming Internal Activities of Business Process Models to Services Compositions

As a service composition language, BPEL imposes as constraint that a business process model should consist only of activities for interacting with other business processes. BPEL provides limited support for implementing internal activities, i.e. activities that are performed by a single business process without involvement of other business processes. BPEL is hence not suitable to implement internal activities that include complex data manipulation. There are a number of options to make BPEL able to implement such internal activities. In this paper we analyse those options based on their feasibility, efficiency, reusability, portability and merging. The analysis indicates that delegating internal activities’ functionality to other services is the best option. We therefore present an approach for transforming internal activities to service invocations. The application of this approach on a business process model results in a service composition model that consists only of activities for interaction

Dynamic integration of context model constraints in web service processes

Autonomic Web service composition has been a challenging topic for some years. The context in which composition takes places determines essential aspects. A context model can provide meaningful composition information for services process composition. An ontology-based approach for context information integration is the basis of a constraint approach to dynamically integrate context validation into service processes. The dynamic integration of context constraints into an orchestrated service process is a necessary direction to achieve autonomic service composition

Model-driven design, simulation and implementation of service compositions in COSMO

The success of software development projects to a large extent depends on the quality of the models that are produced in the development process, which in turn depends on the conceptual and practical support that is available for modelling, design and analysis. This paper focuses on model-driven support for service-oriented software development. In particular, it addresses how services and compositions of services can be designed, simulated and implemented. The support presented is part of a larger framework, called COSMO (COnceptual Service MOdelling). Whereas in previous work we reported on the conceptual support provided by COSMO, in this paper we proceed with a discussion of the practical support that has been developed. We show how reference models (model types) and guidelines (design steps) can be iteratively applied to design service compositions at a platform independent level and discuss what tool support is available for the design and analysis during this phase. Next, we present some techniques to transform a platform independent service composition model to an implementation in terms of BPEL and WSDL. We use the mediation scenario of the SWS challenge (concerning the establishment of a purchase order between two companies) to illustrate our application of the COSMO framework

Distributed aspect-oriented service composition for business compliance governance with public service processes

Service-Oriented Architecture (SOA) offers a technical foundation for Enterprise Application Integration and business collaboration through service-based business components. With increasing process outsourcing and cloud computing, enterprises need process-level integration and collaboration (process-oriented) to quickly launch new business processes for new customers and products. However, business processes that cross organisations’ compliance regulation boundaries are still unaddressed. We introduce a distributed aspect-oriented service composition approach, which enables multiple process clients hot-plugging their business compliance models (business rules, fault handling policy, and execution monitor) to BPEL business processes

Presenting a comparative model of stock investment portfolio optimization based on Markowitz model

Investment is the selection of assets to hold and earn more pro t for greater prosperity in the future. The selection of a portfolio based on the theory of constraint is classical data covering analysis evaluation and ranking Sample function. The in vestment process is related to how investors act in deciding on the types of tradable securities to invest in and the amount and timing. Various methods have been proposed for the investment process, but the lack of rapid computational methods for determining investment policies in securities analysis makes performance appraisal a long term challenge. An approach to the investment process consists of two parts. Major is securities analysis and portfolio management. Securities analysis involvesestimating the bene ts of each investment, while portfolio management involves analyzing the composition of investments and managing and maintaining a set of investments. Classical data envelopment analysis (DEA) models are recognized as accurate for rating and measuring efficient sample performance. Unluckily, this perspective often brings us to get overwhelmed when it's time to start a project. When it comes to limiting theory, the problem of efficient sample selection using a DEA models to test the performance of the PE portfolio is a real discontinuous boundary and concave has not been successful since 2011. In order to solve this problem, we recommend a DEA method divided into business units based on the Markowitz model. A search algorithm is used to introduce to business units and prove their validity. In any business unit, the boundary is continuous and concave. Therefore, DEA models could be applied as PE evaluation. To this end, 25 companies from the companies listed on the Tehran Stock Exchange for the period 1394 to 1399 were selected as the sample size of statistics in data analysis. To analyzethe data, after classi cation and calculations were analysed by MATLAB software, the simulation results show that performance evaluation based on constraint theory based on DEA approach and the Markowitz model presented in this paper is efficient and feasible in evaluating the portfolio of constraint theory

Enforcing reputation constraints on business process workflows

The problem of trust in determining the flow of execution of business processes has been in the centre of research interst in the last decade as business processes become a de facto model of Internet-based commerce, particularly with the increasing popularity in Cloud computing. One of the main mea-sures of trust is reputation, where the quality of services as provided to their clients can be used as the main factor in calculating service and service provider reputation values. The work presented here contributes to the solving of this problem by defining a model for the calculation of service reputa-tion levels in a BPEL-based business workflow. These levels of reputation are then used to control the execution of the workflow based on service-level agreement constraints provided by the users of the workflow. The main contribution of the paper is to first present a formal meaning for BPEL processes, which is constrained by reputation requirements from the users, and then we demonstrate that these requirements can be enforced using a reference architecture with a case scenario from the domain of distributed map processing. Finally, the paper discusses the possible threats that can be launched on such an architecture

Modularity for Security-Sensitive Workflows

An established trend in software engineering insists on using components (sometimes also called services or packages) to encapsulate a set of related functionalities or data. By defining interfaces specifying what functionalities they provide or use, components can be combined with others to form more complex components. In this way, IT systems can be designed by mostly re-using existing components and developing new ones to provide new functionalities. In this paper, we introduce a notion of component and a combination mechanism for an important class of software artifacts, called security-sensitive workflows. These are business processes in which execution constraints on the tasks are complemented with authorization constraints (e.g., Separation of Duty) and authorization policies (constraining which users can execute which tasks). We show how well-known workflow execution patterns can be simulated by our combination mechanism and how authorization constraints can also be imposed across components. Then, we demonstrate the usefulness of our notion of component by showing (i) the scalability of a technique for the synthesis of run-time monitors for security-sensitive workflows and (ii) the design of a plug-in for the re-use of workflows and related run-time monitors inside an editor for security-sensitive workflows