Agent handles the performance of that composite

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agent handles the performance of that composite service and decides which component services will be included (based on execution cost and location of computing host). A provider-domain consists of a working-zone and several portals of Web services. Each portal is reserved to a category of Web services (e.g., travel, education). The working-zones are devised in a way to receive user-agents arriving from the user-domain or from other provider-domains. Within these working zones, installation procedures of user-agents and control procedures of their credentials are performed. Portals of provider-domains are associated with provider-agents; they handle the invocation requests that user-agents submit to the services. A user-agent submits a local request to a provider- agent in case both agents reside in the same provider-domain. This means that the user-agent has migrated to that provider-domain. The user-agent arrives either from the user-domain or from a different provider-domain. In case the user-agent and provider-agent are in separate domains, the user-agent submits a remote request to the provider-agent so that service can be executed [8].
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12 The [7] and the [8] use different criteria for selecting component Web Services into composite one. The system described in [7] is based on the semantic service descriptions (DAML-S) that could be extended by Semantic Search possibilities in the future. The [8] considers two criteria, namely execution cost and location of computing host that actually represents the number of component services that could be executed in the same domain (i.e., indirectly this affects execution time). Thereis an introduction of a new architectural solution as Agent Middle Layer [7] that aims to dynamic service composition and follows the principles: composite services are interpreted as tasks ; Service Mediator is formed dynamically as the coalition of service providing agents (SPAs) participating in the task execution; SPAs join task coalitions only for the time their service is required for the respective task; SPAs are economically rational, autonomous and independent in taking their decisions; services are self-contained modular loosely coupled programs wrapped by SPAs. Approaches of selection elementary Web Services using Mobile Agents become popular, since they allow carrying out composition and execution of Web services in parallel. This is important for fast, reliable, dynamic composition with exception handling during run-time. The technological bases could differ, while the method discussed in [7] and in [8] deserves attention and has to be further investigated by various researches. Fig. 2.2. Agent-Based multi-domain architecture Portal of composite services Pool of user- agents Working-zone User-agents Administrator Service-zone User-domain Working-zone Provider-Agent Working-zone Administrator Provider-domain 2 Provider-domain 1 Provider-domain 4 Provider-domain 3 Portal 21 of Web Services Portal 11 of Web Services Portal 12 of Web Services migration remote invocation migration local invocation remote invocation User-Agent Network
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  • Winter '15
  • MAhmoudali
  • World Wide Web, Web Services, Business process modeling, Web Services Description Language

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