Naseem Ibrahim

Publishing and discovering context-dependent services

In service oriented computing, service providers and service requesters are main interacting entities. A service provider publishes the services it wishes to make public using service registries. A service requester initiates a discovery process to find the service that meets its requirements using the service registries. Current approaches for the publication and discovery do not realize the essential relationship between the service contract and the conditions in which the service can guarantee its contract. Moreover, they do not use any formal methods for specifying services, contracts, and compositions. Without a formal basis it is not possible to justify through a rigorous verification the correctness conditions for service compositions and the satisfaction of contractual obligations in service provisions. In our recent works, we have identified the role of contextual information, trustworthiness information and legal rules in service provision. This paper focuses on the publication and discovery of trustworthy context-dependent services as supported by the novel framework FrSeC. It introduces a novel ranking algorithm that ranks trustworthy context-dependent services according to the degree they match service requesters requirements. Finally, this paper introduces a prototype implementation for the matching and ranking of services as supported by FrSeC.

An Architecture for Managing and Delivering Trustworthy Context-Dependent Services

A precise definition of services is necessary in order to discover, publish, and deliver them. Services, when provided, should satisfy their binding contractual obligations, be seen as trustworthy by the users, and correctly fulfill the needs of the context in which they will be used. The FrSeC architecture proposed in this paper aims to fulfill these needs. The architecture is formally describable, supports the specification, publication, discovery, selection, and composition of services with context-dependent contracts.

Managing and Delivering Trustworthy Context-Dependent Services

Service-oriented architecture (SOA) is emerging as the future of distributed computing and enterprise application development. The two key issues in service-oriented applications should be that every provided service meets the expected trust level set by the service requester, and the provided service satisfies its contract in the context of service provision. In order to enforce these issues, it is necessary to specify in the service its trustworthiness properties, and the relationship between its contracts and the contexts in which it is to be provided. However, current approaches have failed to specify them. The FrSeC architecture proposed in this paper aims to remedy this situation. The architecture supports the specification, publication, discovery, selection, and composition of services, where a service with its functional and nonfunctional aspects is bound to a context-driven contract. A family of Service Provision Specification Languages (SPSL) is introduced to specify the architectural elements. The semantic domain behind SPSL is an abstract architecture description formalism based on set theory and logic. This paper provides an overview of FrSeC framework and gives SPSL descriptions for Service Registry, and Service Requester in FrSeC.

Specification and Verification of Context-dependent Services

Current approaches for the discovery, specification, and provision of services ignore the relationship between the service contract and the conditions in which the service can guarantee its contract. Moreover, they do not use formal methods for specifying services, contracts, and compositions. Without a formal basis it is not possible to justify through formal verification the correctness conditions for service compositions and the satisfaction of contractual obligations in service provisions. We remedy this situation in this paper. We present a formal definition of services with context-dependent contracts. We define a composition theory of services with context-dependent contracts taking into consideration functional, nonfunctional, legal and contextual information. Finally, we present a formal verification approach that transforms the formal specification of service composition into extended timed automata that can be verified using the model checking tool UPPAAL. In [12] and [11], we introduced a formal framework, called FrSeC, that supports the specification, publication, discovery, selection, composition and verification of services with context-dependent contracts. The work reported in this paper is founded on this framework. We provide a formal specification of services with context-dependent contracts and their compositions. The composition theory of services takes into consideration the functional, nonfunctional, legal, and contextual aspects of services. We also present a formal verification approach that transforms the formal specification of service composition into UPPAAL [2] timed automata in order to verify service properties using model checking. Service-oriented Architecture (SOA) is an emerging view of the future of distributed computing and enterprise application development [4]. However, current approaches for the specification, publication, discovery, selection, and provision of services fall short in important respects. First, the relationship between the service contract and the conditions in which the service can guarantee its contract has been ignored, however these are necessary in order to associate the context of the service provider and the context of the service requester. Second, contextual information [3] is not well represented and not rigorously applied in service discovery and service provision. Third, current composition approaches compose only service functionality and ignore nonfunctional requirements. Thus, service contracts, and context information that are part of services are left out of the composition, and verification. Fourth and the last, the published approaches do not use formal methods for the specification of services, contracts, contextual representation and application, and service composition. Without a formal basis it is not possible to justify through formal verification the correctness conditions for service compositions and the satisfaction of contractual obligations in service provisions. The work reported in this paper eliminates these shortcomings. The basic building unit for SOA-based applications is service. It is normally understood that service is an autonomous and platform-independent software program, having its own distinct functionality and a set of capabilities related to this functionality. These capabilities are usually invoked by external consumer programs and are usually expressed via a published service contract. A service contract

A Context-dependent Service Model

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. Received on 08 October 2014 ; accepted on 29 October 2014; published on 16 December 2014

An Architecture for providing and defining student-oriented services

Current learning approaches are teacher oriented. The teacher is in control of the elements of the entire learning process. But different students have different capabilities and constraints. The student should be able to select the teaching style and method that best meets his requirements, while taking into consideration his capabilities and constraints. Due to the wide popularity of service-oriented architecture (SOA) and cloud computing, we propose an extended SOA model. This model extends traditional SOA models to support the provision of richer services that enable service providers to reach a wide range of customers and enable service requesters to find services that best match their requirements taking into consideration their capabilities. In the context of this paper, service providers are course providers and service requesters are the students. This paper also introduces a novel formal model for the specification of our newly introduced richer services.

Verifying Web Services compositions using UPPAAL

A service composition consists of multiple interacting Web Services that provide a functionality to meet a specific set of requirements. It is essential to verify that the functional behavior of the service composition meets the published functionality of the service. Instead of defining a new verification tool to verify the service composition we follow a transformation approach. In this approach, a service composition can be automatically transformed into a model understood by an available verification tool that can then be used to perform the formal verification. The goal in our research is to use different verification tools in order to verify a wide range of properties and target different kinds of systems. This is because different verification tools differ in their requirements and abilities. In this paper, we define the transformation rules to generate a model that can be verified using UPPAAL [1] model checking tool.

Adaptable Discovery and Ranking of Context-Dependent Services

This paper emphasizes the role of contextual information and legal rules in publishing services, formulating contracts, discovering services, and their impact on ranking and adaptability. We use Configured Service concept, which is a package that bundles together service functionality, service contract, and service provision context. Service providers only publish Configured Services in a service registry. Service requesters query the registry to discover available services that can match their requirements. Often there is a semantic gap between the service query and the services in the registry. To deal with this, we discuss three query types. The discovery processes, employing different matching processes that are appropriate for the query types, will rank the services in order to enable the requester choose the most relevant service(s). Ranking is also essential when the number of matchings is large. We identify the different situations that call for rediscovery and re-ranking of service queries. We include a brief account of formalism, within which all these activities are precisely described.

Domain ontology for trustworthy context-dependent services

In recent publications, we have introduced two main concepts. The first is a new service model called ConfiguredService. ConfiguredService extends traditional service models to formally define a service contract to include trustworthiness while considering contextual information. The second concept is a new service provision framework called FrSeC. FrSeC supports the provision of trustworthy context-dependent services. This paper discusses one of the main elements of FrSeC which is the service registry. It utilizes ontology to represent domain knowledge that is used by both service providers and requesters.

Smart Learner-Centric Learning Systems

This paper is concerned with knowledge delivery in learning systems. A learning system is a system through which learners can obtain knowledge. Providers deliver the knowledge in the way they decide is most appropriate. With the wide popularity of e-learning, learners can obtain knowledge from any source in any location in the world. On the other hand, each learner has his/her own learning style(s). But current learning systems are provider oriented. We believe that this is not sufficient. Hence, this paper introduces a smart learner-centric architecture. Smart in the sense that it allows the learner to decide the source of the knowledge he/she is requiring depending on his/her preferred learning style(s). Learner-centric is in the sense that knowledge providers publish their knowledge in a rich definition that specifies the used learning style(s). The architecture allows knowledge requesters to control the source of the knowledge and the learning style used to deliver the knowledge. The proposed architecture is an extension of traditional service-oriented architectures. It extends the definition of traditional service by adding context.