The initial specifications of Web services cope with the issues of service publishing and service discovery but not with the issue of service selection. Service discovery, handled by UDDI and WSDL, alone is not sufficient to find the most appropriate server that can deliver customers' required quality of service (QoS). In this paper, we consider a broker-based approach to provide QoS support in Web services and deal with the selection issue. The broker may implement various selection policies that can range from static policies to dynamic ones, which take into account the current state of servers. Besides, servers may deliver different levels of service to their customers. We model this QoS broker-based scheme by a multi-class queuing model and we study its performance with a probabilistic splitting policy for server selection.
{"title":"A queuing model for service selection of multi-classes QoS-aware Web services","authors":"E. Badidi, L. Esmahi, M. Serhani","doi":"10.1109/ECOWS.2005.3","DOIUrl":"https://doi.org/10.1109/ECOWS.2005.3","url":null,"abstract":"The initial specifications of Web services cope with the issues of service publishing and service discovery but not with the issue of service selection. Service discovery, handled by UDDI and WSDL, alone is not sufficient to find the most appropriate server that can deliver customers' required quality of service (QoS). In this paper, we consider a broker-based approach to provide QoS support in Web services and deal with the selection issue. The broker may implement various selection policies that can range from static policies to dynamic ones, which take into account the current state of servers. Besides, servers may deliver different levels of service to their customers. We model this QoS broker-based scheme by a multi-class queuing model and we study its performance with a probabilistic splitting policy for server selection.","PeriodicalId":265552,"journal":{"name":"Third European Conference on Web Services (ECOWS'05)","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127544245","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Davy Suvée, B. D. Fraine, M. Cibrán, Bart Verheecke, Niels Joncheere, W. Vanderperren
With the increasing popularity of Web services, a number of technologies have emerged that target the integration and composition of Web services as lightweight components. However, a number of problems have been identified in these approaches, for example regarding an overly static integration and lacking support for the modularization of crosscutting concerns. In this paper, we evaluate FuseJ, an architectural description language for unifying aspects and components, as an approach for the composition of Web services. We outline how FuseJ can be used to this end and present an evaluation that compares FuseJ to four other Web service composition approaches according to criteria such as the organization and flexibility of the composition and the support for aspect-oriented software development (AOSD). Although FuseJ does not allow describing complete business processes, we find that it excels at selective and dynamic composition and that it supports advanced separation of concerns without the need to introduce additional constructs.
{"title":"Evaluating FuseJ as a Web service composition language","authors":"Davy Suvée, B. D. Fraine, M. Cibrán, Bart Verheecke, Niels Joncheere, W. Vanderperren","doi":"10.1109/ECOWS.2005.13","DOIUrl":"https://doi.org/10.1109/ECOWS.2005.13","url":null,"abstract":"With the increasing popularity of Web services, a number of technologies have emerged that target the integration and composition of Web services as lightweight components. However, a number of problems have been identified in these approaches, for example regarding an overly static integration and lacking support for the modularization of crosscutting concerns. In this paper, we evaluate FuseJ, an architectural description language for unifying aspects and components, as an approach for the composition of Web services. We outline how FuseJ can be used to this end and present an evaluation that compares FuseJ to four other Web service composition approaches according to criteria such as the organization and flexibility of the composition and the support for aspect-oriented software development (AOSD). Although FuseJ does not allow describing complete business processes, we find that it excels at selective and dynamic composition and that it supports advanced separation of concerns without the need to introduce additional constructs.","PeriodicalId":265552,"journal":{"name":"Third European Conference on Web Services (ECOWS'05)","volume":"66 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126654771","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Yuhong Yan, M. Cordier, Y. Pencolé, Alban Grastien
The goal of Web service effort is to achieve universal interoperability between applications by using Web standards: this emergent technology is a promising way to integrate business applications. A business process can then be seen as a set of Web services that could belong to different companies and interact with each other by sending messages. In that context, neither a global model nor a global mechanism is available to monitor and trace faults when the business process fails. In this paper, we address this issue and propose to use model-based reasoning approaches on discrete-event systems (DES). This paper presents an automatic method to model Web service behaviors and their interactions as a set of synchronized discrete-event systems. This modeling is the first step before tracing the evolution of the business process and diagnosing business process faults.
{"title":"Monitoring Web service networks in a model-based approach","authors":"Yuhong Yan, M. Cordier, Y. Pencolé, Alban Grastien","doi":"10.1109/ECOWS.2005.17","DOIUrl":"https://doi.org/10.1109/ECOWS.2005.17","url":null,"abstract":"The goal of Web service effort is to achieve universal interoperability between applications by using Web standards: this emergent technology is a promising way to integrate business applications. A business process can then be seen as a set of Web services that could belong to different companies and interact with each other by sending messages. In that context, neither a global model nor a global mechanism is available to monitor and trace faults when the business process fails. In this paper, we address this issue and propose to use model-based reasoning approaches on discrete-event systems (DES). This paper presents an automatic method to model Web service behaviors and their interactions as a set of synchronized discrete-event systems. This modeling is the first step before tracing the evolution of the business process and diagnosing business process faults.","PeriodicalId":265552,"journal":{"name":"Third European Conference on Web Services (ECOWS'05)","volume":"285 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114260049","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The successful progress of the Web services concept demands flexible ways for Web services to cooperate and to jointly fulfill a task that is requested by a client. In some applications, the execution of the task is not completely specified beforehand, but could rather be referred to as "best effort". One example is information searches. A flexible invocation of cooperating Web services might mean that their identities are not known beforehand. To achieve trust in the outcome of the task, it is essential that the identities of the cooperating Web services can be tracked in a secure way. It is also essential that the requesting client can decide to what degree the task has been executed. In this paper an approach to securely track identities of Web Services is introduced. The use of one-way messages creates a system where the state of a request is presented by the request itself.
{"title":"Secure choreography of cooperating Web services","authors":"A. Bengtsson, Lars Westerdahl","doi":"10.1109/ECOWS.2005.21","DOIUrl":"https://doi.org/10.1109/ECOWS.2005.21","url":null,"abstract":"The successful progress of the Web services concept demands flexible ways for Web services to cooperate and to jointly fulfill a task that is requested by a client. In some applications, the execution of the task is not completely specified beforehand, but could rather be referred to as \"best effort\". One example is information searches. A flexible invocation of cooperating Web services might mean that their identities are not known beforehand. To achieve trust in the outcome of the task, it is essential that the identities of the cooperating Web services can be tracked in a secure way. It is also essential that the requesting client can decide to what degree the task has been executed. In this paper an approach to securely track identities of Web Services is introduced. The use of one-way messages creates a system where the state of a request is presented by the request itself.","PeriodicalId":265552,"journal":{"name":"Third European Conference on Web Services (ECOWS'05)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124815692","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The most promising feature of the Web services platform is its ability to form new services by combining the capabilities of existing services, i.e., its compos ability. The existing services may themselves be composed of other services, leading to a hierarchical composition. In a hierarchical composition, providers vary in the visibility they have over the other providers in the composition. For example, a provider may not be aware of any providers in the hierarchy other than its parent and children. On the other hand, a provider may be aware of all other providers in the hierarchy. Towards this end, we introduce the notion of spheres of visibility (SoV) as an abstraction to capture the upward/downward visibility aspects of the providers in a hierarchical composition. The latter part of this paper deals with compensation. We outline a compensation mechanism for hierarchical compositions conforming to the visibility restrictions modeled as SoV.
{"title":"Spheres of visibility[Web services]","authors":"Debmalya Biswas, K. Vidyasankar","doi":"10.1109/ECOWS.2005.23","DOIUrl":"https://doi.org/10.1109/ECOWS.2005.23","url":null,"abstract":"The most promising feature of the Web services platform is its ability to form new services by combining the capabilities of existing services, i.e., its compos ability. The existing services may themselves be composed of other services, leading to a hierarchical composition. In a hierarchical composition, providers vary in the visibility they have over the other providers in the composition. For example, a provider may not be aware of any providers in the hierarchy other than its parent and children. On the other hand, a provider may be aware of all other providers in the hierarchy. Towards this end, we introduce the notion of spheres of visibility (SoV) as an abstraction to capture the upward/downward visibility aspects of the providers in a hierarchical composition. The latter part of this paper deals with compensation. We outline a compensation mechanism for hierarchical compositions conforming to the visibility restrictions modeled as SoV.","PeriodicalId":265552,"journal":{"name":"Third European Conference on Web Services (ECOWS'05)","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129945684","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
WS-coordination and WS-CF provide support for distributed activities that require coordination in an environment of Web services. Both specifications are generic coordination frameworks, not specific for any application. Despite their generic character, up to now only transactional protocols have been defined, which leverage these coordination frameworks. In this work we map a distributed activity, that it is not related to transactions, onto the coordination model underlying WS-coordination and WS-CF. Consequently we identify the necessary characteristics of a distributed activity that leverages the coordination frameworks of WS-coordination and WS-CF. We also examine limits of these coordination frameworks and suggest additional mechanisms where support for coordination in particular use cases is not sufficient. In contrast to coordinating distributed transactions, additional problems could arise when other types of activities are subject to coordination. These problems are studied, classified and reviewed in conjunction with the architectural differences of WS-coordination and WS-CF.
{"title":"Rethinking the coordination models of WS-coordination and WS-CF","authors":"F. Leymann, Stefan Pottinger","doi":"10.1109/ECOWS.2005.20","DOIUrl":"https://doi.org/10.1109/ECOWS.2005.20","url":null,"abstract":"WS-coordination and WS-CF provide support for distributed activities that require coordination in an environment of Web services. Both specifications are generic coordination frameworks, not specific for any application. Despite their generic character, up to now only transactional protocols have been defined, which leverage these coordination frameworks. In this work we map a distributed activity, that it is not related to transactions, onto the coordination model underlying WS-coordination and WS-CF. Consequently we identify the necessary characteristics of a distributed activity that leverages the coordination frameworks of WS-coordination and WS-CF. We also examine limits of these coordination frameworks and suggest additional mechanisms where support for coordination in particular use cases is not sufficient. In contrast to coordinating distributed transactions, additional problems could arise when other types of activities are subject to coordination. These problems are studied, classified and reviewed in conjunction with the architectural differences of WS-coordination and WS-CF.","PeriodicalId":265552,"journal":{"name":"Third European Conference on Web Services (ECOWS'05)","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130883318","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
As Web services increasingly become important in distributed computing, some of the flaws and limitations of this technology become more and more obvious. One of this flaws is the discovery of Web services through common methods. Research has been pursued in the field of "semantic Web services". This research is driven by the idea, to describe the functionality of Web services as accurately as possible and to create programs automatically out of already existing Web services. In this paper we discuss a new method for discovery and analysis of Web services. Our approach uses a vector space search engine to index descriptions of already composed services. Rather than generating or automatically composing applications, this approach provides developers with a valuable utility to browse repositories based on already existing information. Furthermore, we propose some additional modifications to extract the maximum amount of semantics from existing service definition repositories.
{"title":"A vector space search engine for Web services","authors":"Christian Platzer, S. Dustdar","doi":"10.1109/ECOWS.2005.5","DOIUrl":"https://doi.org/10.1109/ECOWS.2005.5","url":null,"abstract":"As Web services increasingly become important in distributed computing, some of the flaws and limitations of this technology become more and more obvious. One of this flaws is the discovery of Web services through common methods. Research has been pursued in the field of \"semantic Web services\". This research is driven by the idea, to describe the functionality of Web services as accurately as possible and to create programs automatically out of already existing Web services. In this paper we discuss a new method for discovery and analysis of Web services. Our approach uses a vector space search engine to index descriptions of already composed services. Rather than generating or automatically composing applications, this approach provides developers with a valuable utility to browse repositories based on already existing information. Furthermore, we propose some additional modifications to extract the maximum amount of semantics from existing service definition repositories.","PeriodicalId":265552,"journal":{"name":"Third European Conference on Web Services (ECOWS'05)","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132407683","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Service-centric systems exist in a very dynamic environment, which requires these systems to adapt at runtime in order to keep fulfilling its QoS requirements to its users. In order to create self-adaptive service-centric systems, developers not only design the service architecture, but need to design the self-adaptability aspects in a structured way. Current service standards and technologies do not provide a general architecture in which all aspects for self-adaptability can be designed. In this paper we propose DySOA (dynamic service-oriented architecture), an architecture that extends service-centric applications to make them self-adaptive. DySOA allows developers to explicitly model the process and components that deal with determining the QoS of the running system, with evaluating the QoS, and with reconfiguring the system when necessary. Having the DySOA elements explicit enables separation of concerns, making the DySOA elements adaptable at runtime and reusable in next versions. We demonstrate how to use DySOA with an example.
{"title":"Creating self-adaptive service systems with Dysoa","authors":"I. Bosloper, J. Siljee, J. Nijhuis, D. Hammer","doi":"10.1109/ECOWS.2005.10","DOIUrl":"https://doi.org/10.1109/ECOWS.2005.10","url":null,"abstract":"Service-centric systems exist in a very dynamic environment, which requires these systems to adapt at runtime in order to keep fulfilling its QoS requirements to its users. In order to create self-adaptive service-centric systems, developers not only design the service architecture, but need to design the self-adaptability aspects in a structured way. Current service standards and technologies do not provide a general architecture in which all aspects for self-adaptability can be designed. In this paper we propose DySOA (dynamic service-oriented architecture), an architecture that extends service-centric applications to make them self-adaptive. DySOA allows developers to explicitly model the process and components that deal with determining the QoS of the running system, with evaluating the QoS, and with reconfiguring the system when necessary. Having the DySOA elements explicit enables separation of concerns, making the DySOA elements adaptable at runtime and reusable in next versions. We demonstrate how to use DySOA with an example.","PeriodicalId":265552,"journal":{"name":"Third European Conference on Web Services (ECOWS'05)","volume":"73 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116306457","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Walter Binder, Ion Constantinescu, B. Faltings, Samuel Spycher
In this paper we describe the implementation of multiversion concurrency control on the generalized search tree (GiST), an index structure introduced by Hellerstein. For large-scale service directories, the need arises for a data storage system capable of handling substantial amounts of multidimensional data efficiently, as well as being able to support queries which are natural to the type of data stored in the directory. The GiST is an indexing structure that lends itself particularly well to this type of application. However, the solutions that have been proposed to address concurrency control on the GiST do not meet the requirements of large-scale service directories. The solution proposed here optimizes towards highly concurrent read accesses that are far more frequent than updates to the stored data.
{"title":"Multiversion concurrency control for large-scale service directories","authors":"Walter Binder, Ion Constantinescu, B. Faltings, Samuel Spycher","doi":"10.1109/ECOWS.2005.18","DOIUrl":"https://doi.org/10.1109/ECOWS.2005.18","url":null,"abstract":"In this paper we describe the implementation of multiversion concurrency control on the generalized search tree (GiST), an index structure introduced by Hellerstein. For large-scale service directories, the need arises for a data storage system capable of handling substantial amounts of multidimensional data efficiently, as well as being able to support queries which are natural to the type of data stored in the directory. The GiST is an indexing structure that lends itself particularly well to this type of application. However, the solutions that have been proposed to address concurrency control on the GiST do not meet the requirements of large-scale service directories. The solution proposed here optimizes towards highly concurrent read accesses that are far more frequent than updates to the stored data.","PeriodicalId":265552,"journal":{"name":"Third European Conference on Web Services (ECOWS'05)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129399665","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
L. Ardissono, L. Console, A. Goy, G. Petrone, Claudia Picardi, M. Segnan, D. T. Dupré
Fault management in Web services composed by individual services from multiple suppliers currently relies on a local analysis that does not span across individual services, thus limiting the effectiveness of recovery strategies. We propose to address this limitation of current standards for Web service composition by employing model-based diagnosis to enhance fault analysis. We propose to add diagnostic Web services to the set of Web services providing the overall service, acting as supervisors of their execution, by identifying anomalies and explaining them in terms of faults to be repaired. This approach poses the basis for the development of specialized recovery and compensation techniques aimed at addressing different problems, which could not be otherwise discriminated.
{"title":"Enhancing Web services with diagnostic capabilities","authors":"L. Ardissono, L. Console, A. Goy, G. Petrone, Claudia Picardi, M. Segnan, D. T. Dupré","doi":"10.1109/ECOWS.2005.12","DOIUrl":"https://doi.org/10.1109/ECOWS.2005.12","url":null,"abstract":"Fault management in Web services composed by individual services from multiple suppliers currently relies on a local analysis that does not span across individual services, thus limiting the effectiveness of recovery strategies. We propose to address this limitation of current standards for Web service composition by employing model-based diagnosis to enhance fault analysis. We propose to add diagnostic Web services to the set of Web services providing the overall service, acting as supervisors of their execution, by identifying anomalies and explaining them in terms of faults to be repaired. This approach poses the basis for the development of specialized recovery and compensation techniques aimed at addressing different problems, which could not be otherwise discriminated.","PeriodicalId":265552,"journal":{"name":"Third European Conference on Web Services (ECOWS'05)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2005-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117229907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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