A Framework for Dynamic Web Services Composition

Dynamic composition of web services is a promising approach and at the same time a challenging research area for the dissemination of service-oriented applications. It is widely recognised that service semantics is a key element for the dynamic composition of Web services, since it allows the unambiguous descriptions of a service's capabilities and parameters. This paper introduces a framework for performing dynamic service composition by exploiting the semantic matchmaking between service parameters (i.e., outputs and inputs) to enable their interconnection and interaction. The basic assumption of the framework is that matchmaking enables finding semantic compatibilities among independently defined service descriptions. We also developed a composition algorithm that follows a semantic graph-based approach, in which a graph represents service compositions and the nodes of this graph represent semantic connections between services. Moreover, functional and non-functional properties of services are considered, to enable the computation of relevant and most suitable service compositions for some service request. The suggested end-to-end functional level service composition framework is illustrated with a realistic application scenario from the IST SPICE project

Composition of semantic REST web services

The thesis focuses on the semantic extensions for Swagger standard to support semantic composition. One of the challenges in modern web service development is semantic annotation to support efficient processing and the use of web services. In the thesis, JSON form of Swagger standard 2.0 was extended with semantic annotations which define the semantics of the inputs and outputs of web services. The extensions are based on JSON-LD format and comply with the standard’s limitations, resulting in a fully compatible standard extension. Based on the extended standard definitions the algorithms needed for visualizing semantic composition were developed. We also developed a parser for documents described in extended form of the standard, an algorithm for building a composition graph, an algorithm for searching composition candidates in the graph, an algorithm for suggesting possible solutions in case of failed composition and the logic necessary for semantic reasoning. Besides developing a support web application for semantic composition visualization that uses developed algorithms, we also set up the necessary infrastructure. The thesis proposes a possible approach to semantic composition of web services described in extended Swagger standard form

Composition of semantic REST web services

The thesis focuses on the semantic extensions for Swagger standard to support semantic composition. One of the challenges in modern web service development is semantic annotation to support efficient processing and the use of web services. In the thesis, JSON form of Swagger standard 2.0 was extended with semantic annotations which define the semantics of the inputs and outputs of web services. The extensions are based on JSON-LD format and comply with the standard’s limitations, resulting in a fully compatible standard extension. Based on the extended standard definitions the algorithms needed for visualizing semantic composition were developed. We also developed a parser for documents described in extended form of the standard, an algorithm for building a composition graph, an algorithm for searching composition candidates in the graph, an algorithm for suggesting possible solutions in case of failed composition and the logic necessary for semantic reasoning. Besides developing a support web application for semantic composition visualization that uses developed algorithms, we also set up the necessary infrastructure. The thesis proposes a possible approach to semantic composition of web services described in extended Swagger standard form

Automated web service composition using genetic programming

Automated web service composition is a popular research topic because it can largely reduce human eorts as the business increases. This thesis presents a search-based approach to fully automate web service composition which has a high possibility to satisfy user\u27s functional requirements given certain assumptions. The experiment results show that the accuracy of our composition method using Genetic Programming (GP), in terms of the number of times an expected composition can be derived versus the total number of runs can be over 90%. System designers are users of our method. The system designer begins with a set of available atomic services, creates an initial population containing individuals (i.e. solutions) of candidate service compositions, then repeatedly evaluates those individuals by a fitness function and selects better individuals to generate the next population until a satisfactory solution is found or a termination condition is met. In the context of web service composition, our algorithm of genetic programming is highly improved compared to the traditional genetic programming used in web service composition in three ways: 1. We comply with services knowledge rules such as service dependency graph when generating individuals of web service composition in each population, so we can expect that the convergence process and population quality can be improved. 2. We evaluate the generated individuals in each population through black-box testing. The proportion of successful tests is taken into account by evaluating the fitness function value of genetic programming, so that the convergence rate can be more effective. 3.We take cross-over or mutation operation based on the parent individuals\u27 input and output analysis instead of just choosing by probability as typically done in related work. In this way, better children can be generated even under the same parents. The main contributions of this approach include three aspects. First, less information is needed for service composition. That is, we do not need the composition work- ow and the semantic meaning of each atomic web service. Second, we generate web service composition with full automation. Third, we generate the composition with high accuracy owing to the effect of carefully preparing test cases

Semantic Constraint and QoS-Aware Large-Scale Web Service Composition

Service-oriented architecture facilitates the running time of interactions by using business integration on the networks. Currently, web services are considered as the best option to provide Internet services. Due to an increasing number of Web users and the complexity of users’ queries, simple and atomic services are not able to meet the needs of users; and to provide complex services, it requires service composition. Web service composition as an effective approach to the integration of business institutions’ plans has taken significant acceleration. Nowadays, web services are created and updated in a moment. Therefore, in the real world, there are many services which may not have composability according to the conditions and constraints of the user's preferred choice. In the proposed method for automatic service composition, the main requirements of users including available inputs, expected outputs, quality of service, and the priority are initially and explicitly specified by the user and service composition is done with this information. In the proposed approach, due to a large number of services with the same functionality, at first, the candidate services are reduced by the quality of service-based Skyline method, and moreover, by using an algorithm based on graph search, all possible solutions will be produced. Finally, the user’s semantic constraints are applied on service composition, and the best composition is offered according to user’s requests. The result of this study shows that the proposed method is more scalable and efficient, and it offers a better solution by considering the user’s semantic constraints