Web services composition with QoS bound based on simulated annealing algorithm

In order to enable quality-aware web services selection in the process of service composition,this paper first describes the non-functional requirements of service consumers and the quality of elementary service or composite service as a quality vector,and then models the QoS（quality of service）-aware composition as a multiple criteria optimization problem in extending directed graph.A novel simulated annealing algorithm for QoS-aware web services composition is presented.A normalizing for composite service QoS values is made,and a secondary iterative optimization is used in the algorithm.Experimental results show that the simulated annealing algorithm can satisfy the multiple criteria and global QoS requirements of service consumers.The algorithm produces near optimum solution with much less computation cost.

Task-oriented web service discovery algorithm using semantic similarity for adaptive service composition

In order to achieve adaptive and efficient service composition, a task-oriented algorithm for discovering services is proposed. The traditional process of service composition is divided into semantic discovery and functional matching and makes tasks be operation objects. Semantic similarity is used to discover services matching a specific task and then generate a corresponding task-oriented web service composition （TWC） graph. Moreover, an algorithm for the new service is designed to update the TWC. The approach is applied to the composition model, in which the TWC is searched to obtain an optimal path and the final service composition is output. Also, the model can implement realtime updating with changing environments. Experimental results demonstrate the feasibility and effectiveness of the algorithm and indicate that the maximum searching radius can be set to 2 to achieve an equilibrium point of quality and quantity.

Business domain oriented AI planning for web service composition

In order to improve the effectiveness of the artificial intelligence （AI） planning based web service composition problem, a business domain oriented AI planning algorithm for web service composition is introduced. The algorithm uses the proposed business relation model to minimize the searching space and uses the proposed goal distance as a heuristic rule. Compared with other algorithms tackling web service composition such as AI planning, the proposed algorithm focuses not only on how to convert the web service composition problem to the AI planning problem, but also exerts its effort on how to apply the business feature of web service composition into planning in order to improve the effectiveness. The experiment shows the better performance of the proposed algorithm.

Typed formal model for WS-CDL specification of web services composition

In order to formally reason and verify web services composition described by web services choreography specification WS-CDL,a typed formal model named typed Abstract WS-CDL（web services choreography description language）for WS-CDL specifications is proposed.In typed Abstract WS-CDL,the syntax of type and session,typing rules and operational semantics are formalized;the collaborations of web services are formally described by sessions;the operational semantics of a session can help to formally reason the execution of the choreography;the typing rules can help to formally check the data type consistency of exchanged information between web services and capture run-time errors due to type mismatches.Particularly,the concepts of type assumption set extension and type assumption set compatibility are proposed,and the merging algorithm of type assumption sets is defined so as to eliminate type assumption conflict.Based on the formal model,typed mapping rules for mapping web services choreography to orchestration is also defined.With the typed mapping rules,orchestration stubs and their type assumption sets can be generated from a given choreography; thus, web services composition can be verified at choreography and orchestration levels,respectively.The model is proved to have properties of type safety,and how the model can help to reason and verify web services composition is illustrated through a case study.

MAS-based dynamic web service composition formal model

Applying dynamic web services composition is one of the important schemas for solving service-oriented architecture （SOA）and service-oriented computing（SOC）.For implementing dynamic web services composition,the multi agent system （MAS）is applied to web services composition.First, the essentials of the MAS and web services composition are analyzed and their relationship is discussed.Secondly, an MAS-based architecture is designed for dynamic web services composition,and it is named as CSMWC.A Jade tool is used to implement the major components.The architecture can primarily implement syntactic level dynamic web services composition,and it gives a basis for semantic level dynamic web services composition.For specifying the correctness of the architecture,by using pi-calculus,the architecture of the MAS is formally described,and its dynamic properties and adaptability are reasoned.Finally,it demonstrates the idea proposed by the Pi4SOA tool.

Service composition algorithm using semantic constraint to implement user personality

In order to improve the efficiency and quality of service composition,a service composition algorithm based on semantic constraint is proposed.First, a user’s requirements and services from a service repository are compared with the help of a matching algorithm.The algorithm has two levels and filters out the services which do not match the user’s constraint personality requirements.The mechanism can reduce the searching scope at the beginning of the service composition algorithm.Secondly,satisfactions of those selected services for the user’s personality requirements are computed and those services,which have the greatest satisfaction value to make up the service composition,are used.The algorithm is evaluated analytically and experimentally based on the efficiency of service composition and satisfaction for the user’s personality requirements.

Reachability analysis of web service compositions via NWA

In order to improve the design and implementation quality of web service compositions,formal methods are used to model them and certain properties are verified.WCFA （web service interface control flow automata）is used to model web services,especially the control flow and possible interactions with other web services.A web service composition consists of a set of interacting WCFA.The global behavior of web service compositions is captured by NWA（nested word automata）.A variation of the depth-first search algorithm is used to transform a set of WCFA into an NWA.State formulae and call stacks at each node of NWA are computed by a path-sensitive reachability analysis.Safety properties,call stack inspection properties and pre/post-conditions of service invocations are described by assertions.Then verification of these assertions is carried out by an automated SAT tool.

Dynamic services selection algorithm in Web services composition supporting cross-enterprises collaboration

Based on the deficiency of time convergence and variability of Web services selection for services composition supporting cross-enterprises collaboration,an algorithm QCDSS(QoS constraints of dynamic Web services selection)to resolve dynamic Web services selection with QoS global optimal path,was proposed.The essence of the algorithm was that the problem of dynamic Web services selection with QoS global optimal path was transformed into a multi-objective services composition optimization problem with QoS constraints.The operations of the cross and mutation in genetic algorithm were brought into PSOA(particle swarm optimization algorithm),forming an improved algorithm(IPSOA)to solve the QoS global optimal problem.Theoretical analysis and experimental results indicate that the algorithm can better satisfy the time convergence requirement for Web services composition supporting cross-enterprises collaboration than the traditional algorithms.

Heuristic web service composition method based on domain ontology

In order to realize automatic web service composition, a heuristic web service composition method based on domain ontology is proposed. First, this method integrates the domain ontology and the artificial intelligence （AI） planning algorithm. Then, it uses the domain ontology and its reasoning capability to infer the semantic relationship among parameters. Finally, it transforms the web service composition problem into the planning problem based on the AI planning heuristic algorithm. The preliminary experimental results show that the above method compensates for the lack of semantics in the previous AI planning method and it can satisfy the requirements of quality and efficiency of composition, thus generating composite web services according to customer requirements automatically and efficiently.

Immune Algorithm for Selecting Optimum Services in Web Services Composition

For the problem of dynamic optimization in Web services composition, this paper presents a novel approach for selecting optimum Web services, which is based on the longest path method of weighted multistage graph. We propose and implement an Immune Algorithm for global optimization to construct composed Web services. Results of the experimentation illustrates that the algorithm in this paper has a powerful capability and can greatly improve the efficiency and veracity in service selection.

Distributed Information Flow Verification for Secure Service Composition in Smart Sensor Network

Accelerate processor, efficient software and pervasive connections provide sensor nodes with more powerful computation and storage ability, which can offer various services to user. Based on these atomic services, different sensor nodes can cooperate and compose with each other to complete more complicated tasks for user. However, because of the regional characteristic of sensor nodes, merging data with different sensitivities become a primary requirement to the composite services, and information flow security should be intensively considered during service composition. In order to mitigate the great cost caused by the complexity of modeling and the heavy load of single-node verification to the energy-limited sensor node, in this paper, we propose a new distributed verification framework to enforce information flow security on composite services of smart sensor network. We analyze the information flows in composite services and specify security constraints for each service participant. Then we propose an algorithm over the distributed verification framework involving each sensor node to participate in the composite service verification based on the security constraints. The experimental results indicate that our approach can reduce the cost of verification and provide a better load balance.

Automatic Web services composition algorithm based on optimal matching

A novel layered method was proposed to solve the problem of Web services composition.In this method,services composition problem was formally transformed into the optimal matching problem of every layer,then optimal matching problem was modeled based on the hypergraph theory,and solved by computing the minimal transversals of the hypergraph.Meanwhile,two optimization algorithms were designed to discard some useless states at the intermediary steps of the composition algorithm.The effectiveness of the composition method was tested by a set of experiments,in addition,an example regarding the travel services composition was also given.The experimental results show that this method not only can automatically generate composition tree whose leaf nodes correspond to services composition solutions,but also has better performance on execution time and solution quality by adopting two proposed optimization algorithms.

A Distributed Optimal Scheme Based on Local QoS for Web Service Composition

The goal of web service composition is to choose an optimal scheme according to Quantity of Service （QoS） which selects instances in a distributed network. The networks are clustered with some web services such as ontologies, algorithms and rule engines with similar function and interfaces. In this scheme, web services acted as candidate service construct a distributed model which can＇t obtain the global services＇ information. The model is utilized to choose instances according to local QoS information in the progress of service composition. Some QoS matrixes are used to record and compare the instance paths and then choose a better one. Simulation result has proven that our ~pproach has a tradeoff between efficiency and ~quality.

A Formal Model for BPEL4WS Description of Web Service Composition

Communicating Sequential Processes （CSP） is a kind of process algebra, which is suitable for modeling and verifying Web service composition. This paper describes how to model Web service composition with CSP. A set of rules for translating composition constructor of Business Process Execution Language for Web Services （BPEL4WS） to CSP notations is defined. According to the rules that have been defined, the corresponding translation algorithm is designed and illustrated with examples . The methods for model checking, model verification and model simulation are also introduced.

A Testing Method for Web Services Composition Based on Data-Flow

This paper proposes a method of data-flow testing for Web services composition. Firstly, to facilitate data flow analysis and constraints collecting, the existing model representation of business process execution language （BPEL） is modified in company with the analysis of data dependency and an exact representation of dead path elimination （DPE） is proposed, which over-comes the difficulties brought to dataflow analysis. Then defining and using information based on data flow rules is collected by parsing BPEL and Web services description language （WSDL） documents and the def-use annotated control flow graph is created. Based on this model, data-flow anomalies which indicate potential errors can be discovered by traversing the paths of graph, and all-du-paths used in dynamic data flow testing for Web services composition are automatically generated, then testers can design the test cases according to the collected constraints for each path selected.

RESEARCH ON REUSE-BASED WEB SERVICES COMPOSITION

Objective To solve the three principal problems for reusing the software components, i.e., existence, discovery and availability principles, web services provided a new solution for reusing and assembling web software or components under distributed environment with a series of XML-based protocols. Methods A 4+1 meta-model between atomic services, such as Sequence, Parallelism, Alternation, Substitute and Iteration, and a kind of service composition description language in composition process are investigated. Furthermore, an architecture-based service composition model with Ontology Engine is proposed, which is based on the software architecture life-cycle model and provides a mechanism for services composition with dynamic management and deployment. Results The results of the prototype system development show that the service-composed application not only reused the web service components, but also reused the data resources located in distributed databases. Conclusion The method of reused-based web services composition observably decreases the period and cost of development and greatly improves the programming efficiency.

A Service Composition Approach Based on Sequence Mining for Migrating E-learning Legacy System to SOA

With the fast development of business logic and information technology, today＇s best solutions are tomorrow＇s legacy systems. In China, the situation in the education domain follows the same path. Currently, there exists a number of e-learning legacy assets with accumulated practical business experience, such as program resource, usage behaviour data resource, and so on. In order to use these legacy assets adequately and efficiently, we should not only utilize the explicit assets but also discover the hidden assets. The usage behaviour data resource is the set of practical operation sequences requested by all users. The hidden patterns in this data resource will provide users＇ practical experiences, which can benefit the service composition in service-oriented architecture （SOA） migration. Namely, these discovered patterns will be the candidate composite services （coarse-grained） in SOA systems. Although data mining techniques have been used for software engineering tasks, little is known about how they can be used for service composition of migrating an e-learning legacy system （MELS） to SOA. In this paper, we propose a service composition approach based on sequence mining techniques for MELS. Composite services found by this approach will be the complementation of business logic analysis results of MELS. The core of this approach is to develop an appropriate sequence mining algorithm for mining related data collected from an e-learning legacy system. According to the features of execution trace data on usage behaviour from this e-learning legacy system and needs of further pattern analysis, we propose a sequential mining algorithm to mine this kind of data of tile legacy system. For validation, this approach has been applied to the corresponding real data, which was collected from the e-learning legacy system; meanwhile, some investigation questionnaires were set up to collect satisfaction data. The investigation result is 90% the same with the result obtained through our approach.

Fishery Web Service Composition Method Based on Ontology

Various fishery information systems have been developed in different times and on different platforms. Wet） service application composition is crucial in the sharing and integration of fishery data and information. In the present paper, a heuristic web service composition method based on fishery ontology is presented, and the proposed web services are described. Ontology reasoning capability was applied to generate a service composition graph. The heuristic function was introduced to reduce the searching space. The experimental results show that the algorithm used considers the services semantic similarity and adiusts web service composition plan by dynamically relying on the empirical data.

A colored Petri net-based model for web service composition

In this paper, a model based colored Petri net （CPN） to provide semantic support for web service composition is proposed, and the reliability and maintainability of composite services are improved. The composite constructs in the model are sequence, concurrent, choice, loop and replace. The web service is formally defined by a CPN. A closed composing algebra is defined to obtain a framework which enables declarative composition of web services. Availability, confidentiality, and integrity of composite service are analyzed within the framework of the model based CPN.

Service composition based on discrete particle swarm optimization in military organization cloud cooperation

This paper addresses the problem of service composition in military organization cloud cooperation（MOCC）. Military service providers（MSP） cooperate together to provide military resources for military service users（MSU）. A group of atom services, each of which has its level of quality of service（QoS）, can be combined together into a certain structure to form a composite service. Since there are a large number of atom services having the same function, the atom service is selected to participate in the composite service so as to fulfill users＇ will. In this paper a method based on discrete particle swarm optimization（DPSO） is proposed to tackle this problem. The method aims at selecting atom services from service repositories to constitute the composite service, satisfying the MSU＇s requirement on QoS. Since the QoS criteria include location-aware criteria and location-independent criteria, this method aims to get the composite service with the highest location-aware criteria and the best-match location-independent criteria. Simulations show that the DPSO has a better performance compared with the standard particle swarm optimization（PSO） and genetic algorithm（GA）.