casa 14(2): e3

Research Article

A Context-dependent Service Model

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  • @ARTICLE{10.4108/casa.1.2.e3,
        author={Naseem Ibrahim and Vangular Alagar and Mubarak  Mohammmed},
        title={A Context-dependent Service Model},
        journal={EAI Endorsed Transactions on Context-aware Systems and Applications},
        keywords={ConfiguredService Model, Context-dependence, Trustworthy Services, Composition Methods, Formal Verification},
  • Naseem Ibrahim
    Vangular Alagar
    Mubarak Mohammmed
    Year: 2014
    A Context-dependent Service Model
    DOI: 10.4108/casa.1.2.e3
Naseem Ibrahim1,*, Vangular Alagar2, Mubarak Mohammmed2
  • 1: Albany State University, Albany, GA, USA
  • 2: Concordia University, Montreal, QC, Canada
*Contact email:


In service-oriented systems a service invariably is bound to a contract. This contract includes the functionalities and quality of services guarantees that the provider can make. But such guarantees are not absolute. A service cannot guarantee its contract in all situations. It can only guarantee its contract in a predefined set of conditions. These conditions are usually related to the context of the service provider and requester. Yet, most of service-oriented applications use only service functionality as the basis of providing services and building system compositions. To remedy this situation, in this article both functionality and contract of a service are integrated into a single concept, called ConfiguredService, and formalized as a higher-order data type. The service part that includes the functionality, nonfunctional properties, service parameters, and data of the service requester, is loosely coupled to the contract part that includes trustworthiness claims, legal and business rules governing the service provision, and the context information pertaining to the provider and receiver. This loose coupling allows the creation of many ConfiguredServices, which share the same functionality but possess different contract parts. To facilitate dynamic service adaptation, we introduce a syntax and semantics for extending or modifying a ConfiguredService.