Intention Driven Service Composition with Patterns

International Journal of Cooperative Information Systems, 2005

This paper addresses the issue of automatic service composition. We first develop a framework in which the exported behavior of a service is described in terms of a socalled execution tree, that is an abstraction for its possible executions. We then study the case in which such exported behavior (i.e. the execution tree of the service) can be represented by a finite state machine (i.e. finite state transition system). In this specific setting, we devise sound, complete and terminating techniques both to check for the existence of a composition, and to return a composition, if one exists. We also analyze the computational complexity of the proposed algorithms. Finally, we present an open source prototype tool, called ESC (E-Service Composer), that implements our composition technique. To the best of our knowledge, our work is the first attempt to provide a provably correct technique for the automatic synthesis of service composition, in a framework where the behavior of services is explicitly specified. 333 334 D. Berardi et al. service directory, which is the subject providing a repository/registry of service descriptions, where providers publish their services and requestors find services; and, (iii) the service requestor, also referred to as client, which is the subject looking for and invoking the service in order to fulfill some goals. A requestor discovers a suitable service in the directory, and then connects to the specific service provider in order to invoke the service.

2012

Abstract The incapability to foresee or react to all the events that take place in a specific environment supposes an important handicap for Ambient Intelligence systems, expected to be self-managed, proactive, and goal-driven. Endowing such systems with capabilities to understand and reason about context seems like a promising solution to overcome this hitch. Supported on the service-oriented paradigm, composing rather than combining services provides a reasonable mean to implement versatile systems.

… 2009. EDOCW 2009 …, 2009

A pragmatic and straightforward approach to semantic service discovery is to match inputs and outputs of user requests with the input and output requirements of registered service descriptions. This approach can be extended by using pre-conditions, effects and semantic annotations (meta-data) in an attempt to increase discovery accuracy. While on one hand these additions help improve discovery accuracy, on the other hand complexity is added as service users need to add more information elements to their service requests. In this paper we present an approach that aims at facilitating the representation of service requests by service users, without loss of accuracy. We introduce a Goal-Based Service Framework (GSF) that uses the concept of goal as an abstraction to represent service requests. This paper presents the core concepts and relations of the Goal-Based Service Ontology (GSO), which is a fundamental component of the GSF, and discusses how the framework supports semantic service discovery and composition. GSO provides a set of primitives and relations between goals, tasks and services. These primitives allow a user to represent its goals, and a supporting platform to discover or compose services that fulÀl them.

Web Services, 2005 …, 2005

To fully utilize web-services, users and applications should be able to discover, deploy, compose and synthesize services automatically. This automation can take place only if a formal semantic description of the web-services is available. In this paper we present the design of USDL (Universal Service-Semantics Description Language), a language for formally describing the semantics of web-services. USDL is based on the Web Ontology Language (OWL) and employs Word-Net as a common basis for understanding the meaning of services. USDL can be regarded as formal program documentation that will allow sophisticated conceptual modeling and searching of available web-services, automated service composition, and other forms of automated service integration. The design of USDL is presented, along with examples, and its formal semantics given. A theory of service composition for USDL is presented and proved sound and complete.

… , 2009. ITNG'09. …, 2009

Service-Oriented Computing allows new applications to be developed by using and/or combining services offered by different providers. Service discovery and composition are performed aiming to comply with the client's request in terms of functionality and expected outcome. In this paper we present a framework for dynamic service discovery and composition. This framework is based on goals and tasks as the means to represent the client's expected outcome and functionality, respectively. The framework encompasses a goal-based service ontology, a set of domain and task ontologies and a supporting service platform with a service matching and composition algorithm. The client informs the platform about the goal to be fulfilled. The platform's matching algorithm searches in the repository for services that can fulfill the client's goal. Moreover, the platform gathers client's contextual information to use as inputs for the services and thus, reduce the need for client interaction. If no single service is able to fulfill the user's goal, a service composition is then performed. * The present work is partly funded by the Freeband Communication project A-Muse (http://a-muse.freeband.nl). A-Muse is sponsored by the Dutch government under contract BSIK 03025.

Lecture Notes in Computer Science, 2007

Despite the growing acceptance of SOA, service-oriented computing remains a computing mechanism to speed-up the design of software applications by assembling ready-made services. We argue that it is difficult for business people to fully benefit of the SOA if it remains at the software level. The paper proposes a move towards a description of services in business terms, i.e. intentions and strategies to achieve them and to organize their publication, search and composition on the basis of these descriptions. In this way, it leverages on the SOA to an intentional level, the ISOA. We present ISM, the model to describe intentional services, and to populate the service registry. We highlight its intention driven perspective for service description, retrieval and composition. Thereafter, we propose a methodology to determine intentional services that meet business goals. Finally, we introduce agent architecture to support model driven execution of intentional services.

… 2005. NWeSP 2005 …, 2005

To fully utilize Web-services, users and applications should be able to discover, deploy, compose and synthesize services automatically. This automation can take place only if a formal semantic description of the Web-services is available. In this paper we present the design of USDL (Universal Service Description Language), a language for formally describing the semantics of information utilized and produced by Web-services. USDL is based on the Web ontology language (OWL) and employs WordNet as a common basis for understanding the meaning of services. USDL can be regarded as formal program documentation that will allow sophisticated conceptual modeling and searching of available Web-services, automated service composition, and other forms of automated service integration. The preliminary design of USDL is presented, along with examples, and its formal semantics given.

2010

A common practice in service-orientation is the creation of a composite service by combining a set of other services. As discussed in this article, the orchestration of services to construct a new service requires several service interactions. This is why the construction of a composite service can be a complex and time-consuming task. Some services in a service composition can have the role of providing other services with (additional) input data. The pattern language in this article can help to design the service interactions that are needed for provisioning input data.

Electronic Notes in Theoretical Computer Science, 2009

Many efforts are currently devoted to provide software developers with methods and techniques that can endow service-oriented computing with systematic and accountable engineering practices. To this purpose, a number of languages and calculi have been proposed within the S project that address different levels of abstraction of the software engineering process. Here, we report on two such languages and the way they can be formally related within an integrated approach that can lead to verifiable development of service components from more abstract architectural models of business activities.

Service-Oriented Architecture (SOA) has emerged as a prominent design style that enables an IT infrastructure to allow different applications to participate in business processes, regardless of their underlying features, by encapsulating them as platform-independent entities that become available via a certain network, primarily the Internet. In order to effectively discover and use the most suitable services, service description should provide a complete behavior model, describing the inputs and preconditions that are required before execution, as well as the outputs and effects of a successful execution. Such service specifications are indispensable in a variety of activities, such as conformance and verification checks, adaptation evaluation and deducing composability of services. Service specifications rely on the expression of conditions that should hold before and after service execution. Such specifications are prone to a family of problems, known in the AI literature as the frame, ramification and qualification problems. These problems deal with the succinct and flexible representation of non-effects, indirect effects and preconditions, respectively. Research in services has largely ignored these problems, at the same time ignoring their effects, such as compromising the integrity and correctness of services and service compositions and the inability to provide justification for unexpected execution results. To address these issues, this thesis proposes the Web Service Specification Language (WSSL), a novel, semantics-aware language for the specification and composition of services, independent of service design models. WSSL's foundation is the fluent calculus, a specification language for robots that offers solutions to the frame, ramification and qualification problems. Further language extensions achieve three major goals: realize service composition via planning, supporting non-deterministic constructs, such as conditionals and loops; include specification of QoS profiles; and support partially observable service states. To investigate WSSL's applicability and demonstrate its benefits, we analyze correctness of the composition extension, decidability and complexity of the underlying theory, as well as compatibility with other related languages in service science. Moreover, an innovative service composition and verification framework is implemented, that advances state-of-the-art by satisfying several desirable requirements simultaneously: ramifications and partial observability in service and goal modeling; non-determinism in composition schemas; dynamic binding of tasks to concrete services; explanations for unexpected behavior; QoS-awareness through pruning and ranking techniques based on heuristics and task-specific goals and an all-encompassing QoS aggregation method for global goals. Experimental evaluation is performed using synthetically generated specifications and composition goals, investigating performance scalability in terms of execution time, as well as optimality with regard to the produced composite process. The results show that, even in the presence of ramifications in some specifications, functional planning is efficient for repositories up to 500 specifications. Also, the cost of functional discovery per single service is insignificant, hence achieving good performance even when executed for multiple candidate plans. Finally, optimality relies mainly on defining suitable problem-specific heuristics; thus, its success depends mostly on the expertise of the composition designer.