On Topological Structure of Web Services Networks for Composition

Web service composition is the process of synthesizing a new composite service using a set of available Web services in order to satisfy a client request that cannot be treated by any available Web services. The Web services space is a dynamic environment characterized by a huge number of elements. Furthermore, many Web services are offering similar functionalities. In this paper we propose a model for Web service composition designed to address the scale effect and the redundancy issue. The Web services space is represented by a two-layered network architecture. A concrete similarity network layer organizes the Web services operations into communities of functionally similar operations. An abstract interaction network layer represents the composition relationships between the sets of communities. Composition synthesis is performed by a two-phased graph search algorithm. First, the interaction network is mined in order to discover abstract solutions to the request goal. Then, the abstract compositions are instantiated with concrete operations selected from the similarity network. This strategy allows an efficient exploration of the Web services space. Furthermore, operations grouped in a community can be easily substituted if necessary during the composition's synthesis's process.

… Conference of New …, 2010

Along with a continuously growing number of publicly available Web services (WS), we are witnessing a rapid development in semantic-related web technologies, which lead to the apparition of semantically described WS. In this work, we perform a comparative analysis of the syntactic and semantic approaches used to describe WS, from a complex network perspective. First, we extract syntactic and semantic WS dependency networks from a collection of publicly available WS descriptions. Then, we take advantage of tools from the complex network field to analyze them and determine their topological properties. We show WS dependency networks exhibit some of the typical characteristics observed in real-world networks, such as small world and scale free properties, as well as community structure. By comparing syntactic and semantic networks through their topological properties, we show the introduction of semantics in WS description allows modeling more accurately the dependencies between parameters, which in turn could lead to improved composition mining methods.

Strategic Advantage of …, 2010

The number of publicly available Web services (WS) is continuously growing. To perform efficient WS discovery, it is desirable to organize the WS space. Works in this direction propose to group WS according to certain shared properties. Such groups commonly called communities are based either on similarity or on interaction between WS. In this paper we focus on the former, and propose a new network-based approach to extract communities from a WS collection. This process is three-stepped: first we define several similarity functions able to compare WS operations, second we use them to build so-called similarity networks, and third we identify communities under the form of specific structures in these networks. We apply our method on a collection of real-world WS and comment the resulting communities. Finally, we additionally provide an analysis and an interpretation of our similarity networks with a complex networks perspective.

2011

Service Oriented Architecture (SOA) can be defined as a way of defining and implementing enterprise applications that deals with the intercommunication of loosely coupled, coarse grained (business level), reusable artifacts (services). In this paper, we attempt to mathematically model the preliminary steps in the larger problem of providing an optimal architecture. The problem is treated as a complex network, particularly a process-task-network. We employ statistical and graph-theoretic methods namely, Jaccard's distance analysis, Multiple Correspondence method and the Minimum Spanning Tree method, to find appropriate clusters. These methods are used to cluster tasks across business processes to propose services. Additional properties and features of these clusters are discussed. We propose a leverage factor which demonstrates the importance of a task within the service and its impact on service composition.

Many real-world complex systems such as social, biological, information as well as technological systems results of a decentralized and unplanned evolution which leads to a common structuration. Irrespective of their origin, these so-called complex networks typically exhibit small-world and scale-free properties. Another common feature is their organisation into communities. In this paper, we introduce models of interaction networks based on the composition process of syntactic and semantic Web services. An extensive experimental study conducted on a benchmark of real Web services shows that these networks possess the typical properties of complex networks (small-world, scale-free). Unlike most social networks, they are not transitive. Using a representative sample of community detection algorithms, a community structuration is revealed. The comparative evaluation of the discovered community structures shows that they are very similar in terms of content. Furthermore, the analysis performed on the community structures and on the communities themselves, leads us to conclude that their topological properties are consistent.

IEEE Transactions on Services Computing, 2016

In this paper we present a theoretical analysis of graph-based service composition in terms of its dependency with service discovery. Driven by this analysis we define a composition framework by means of integration with fine-grained I/O service discovery that enables the generation of a graph-based composition which contains the set of services that are semantically relevant for an input-output request. The proposed framework also includes an optimal composition search algorithm to extract the best composition from the graph minimising the length and the number of services, and different graph optimisations to improve the scalability of the system. A practical implementation used for the empirical analysis is also provided. This analysis proves the scalability and flexibility of our proposal and provides insights on how integrated composition systems can be designed in order to achieve good performance in real scenarios for the Web.

Nowadays, Web services (WS) remain a main actor in the implementation of distributed applications. They represent a new promising paradigm for the development, deployment and integration of Internet applications. The aim of Web services composition is to use the skills of several departments to resolve any problem that cannot be solved individually. The result of this composition is a compound of Web services that define how they will be used. In this paper, we propose an approach for automatic web services composition based on the concepts of directed graphs for the representation and description of Web services, and the ordering of web services compound execution. In this context, the user query, defined by a set of inputs and outputs, can be viewed as a directed graph composed of Web services.

Service Oriented Computing and Applications, 2014

With the increasing popularity of Web Services and Service-Oriented Architecture, we need infrastructure to discover and compose Web services. In this paper, we present a generalized semantics-based technique for automatic service composition that combines the rigor of processoriented composition with the descriptiveness of semantics. Our generalized approach presented in this paper introduces the use of a conditional directed acyclic graph where complex interactions, containing control flow, information flow, and pre-/post-conditions are effectively represented. Composition solution obtained is represented semantically as OWLS documents. Web service composition will gain wider acceptance only when users know that the solutions obtained are comprised of trustworthy services. We present a framework that not only uses functional and non-functional attributes provided by the Web service description document but also filters and ranks solutions based on their trust rating that is computed using Centrality Measure of Social Networks. Our contributions are applied for automatic workflow generation in context of the currently important bioinformatics domain. We evaluate our engine for automatic workflow generation of a phylogenetic inference task. We also evaluate our engine

Jiang Zi-Long Naji Hasan.A.H, Gao Shu, AL-Gabri Malek, 2013

As the spread of web services, the composition of web services becomes a hot topic on both the academia and IT domains. The composition of services depends on the semantic descriptions, which describe the functionality of the services, provided by the owners of services and on the description of the consumer's requests. The composition also depends on nonfunctional descriptions (QoS). In this paper, we present an approach of web services composition based on both semantic description and QoS. The proposed approach builds a network of web services by matchmaking the semantic concepts in OWLS , using the outputsinputs similarity between services. Then, many composed assemblies can be created by combining web services in the semantic network according to consumer's needs. Those composed assemblies will be ranked by the QoS that provided by the consumer and the suitable one will be sent back to the consumer. This approach takes the advantages from Pellete DL

Advances in Information …, 2011

Web services represent a system with a huge number of units and many various and complex interactions. Complex networks as a tool for modelling and analyzing natural environments seem to be well adapted to such a complex system. To describe a set of Web services we propose three Web services network models based on the notions of dependency, interaction and similarity. Using the WS-NEXT extractor we instantiate the models with a collection of Web services descriptions. We take advantage of complex network properties to provide an analyzis of the Web services networks. Those networks and the knowledge of their toplogical properties can be exploited for the discovery and composition processes.