Brahmananda Sapkota

A Multi-criteria Service Ranking Approach Based on Non-Functional Properties Rules Evaluation

Service oriented architectures (SOAs) are quickly becoming the de-facto solutions for providing end-to-end enterprise connectivity. However realizing the vision of SOA requires, among others, solutions for one fundamental challenge, namely service ranking. Once a set of services that fulfill the requested functionality is discovered, an ordered list of services needs to be created according to users preferences. These preferences are often expressed in terms of multiple non-functional properties (NFPs). This paper proposes a multi-criteria ranking approach for semantic web services. We start by briefly introducing ontological models for NFPs. These models are used to specify rules which describe NFP aspects of services and goals/requests. The ranking mechanism evaluates these NFPs rules using a reasoning engine and produces a ranked list of services according to users preferences.

Distributed Web Service Discovery Architecture

In this paper, we present a distributed Web service discovery architecture that is designed to be reliable, flexible and scalable. The architecture is based on the concept of distributed shared space and intelligent search among a subset of spaces. It allows the publishing of Web service descriptions as well as to submit requests to discover the Web service of user’s interests. The Web service capabilities and the user requests (goal) are described using a Resource Description Framework (RDF) data model. The architecture supports integration of applications running on different resource specific devices. An application scenario is presented to illustrate the functionality of the proposed architecture.

Discovery in grid and web services environments: A survey and evaluation

An important step in realizing the vision of both Web services and Grid is the provision of a robust, automatic and reliable solution for finding services or resources in such environments. Different solutions to this problem were already proposed, each with its specific model and realization. Although all solutions address the same problem, it is very difficult for a non-expert and even for an expert in the field to decide if and why one solution is better then another. This paper proposes a systematic set of criteria, a framework, that can help in the evaluation of different discovery approaches. Furthermore some of the most relevant discovery approaches in Web services and Grid environments are surveyed and evaluated according to the proposed evaluation framework.

Triple space computing: adding semantics to space-based computing

Triple Space Computing (TSC) is a very simple and powerful paradigm that inherits the communication model from Tuple Space Computing and projects it in the context of the Semantic Web In this paper, we propose Triple Space Computing as a new communication and coordination framework for Semantic Web and Semantic Web Services We identify the value added by TSC and propose the overall architecture of TSC and the interactions among different components.

Role of triple space computing in semantic web services

This paper presents Triple space computing and described the role it can play in bringing Semantic Web Services to the next level of maturity. In particular the shortcomings of current Semantic Web services are identified and the role of Triple Space computing can play in resolving these shortcomings is described.

Estimating the number of answers with guarantees for structured queries in p2p databases

Structured P2P overlays supporting standard database functionalities are a popular choice for building large-scale distributed data management systems. In such systems, estimating the number of answers for structured queries can help approximating query completeness, but is especially challenging. In this paper, we propose to use routing graphs in order to achieve this. We introduce the general approach and briefly discuss further aspects like overhead and guarantees.

Process mediation based on triple space computing

Web services are inherently heterogeneous at both data and behavioral levels because of the nature of the Web, which is the main obstacle to the usability of Web services. The heterogeneity at a behavioral level is generally addressed by process mediation, in which the message flow is adjusted to suit the behavior of Web services involved in a given interaction. In this paper, we present a novel approach for process mediation, and propose an architectural for process mediation based on Triple Space Computing to solve resolvable message sequence mismatches. These resolvable mismatches can be classified into five classes for unveiling their essence. This work provides a basis for the generalization of mismatches themselves, as well as a potentially uniform solution to address these mismatches.

Peer-to-Peer technology usage in web service discovery and matchmaking

This paper presents a dynamic and scalable mechanism for discovery of semantically enriched descriptions of Web services. By employing Web Service Modeling Ontology (WSMO) as the underlying framework for describing both user requests and Web services, and combining it with the usage of Peer-to-Peer technology in this context, a scalable, distributed, dynamic and flexible discovery mechanism is obtained. A use case scenario is presented for supporting the viability of such a mechanism.

From Workflow Models to Executable Web Service Interfaces

Workflow models have been used and refined for years to execute processes within organisations. To deal with collaborative processes (choreographies) these internal workflow models have to be aligned with the external behaviour advertised through Web service interfaces. However, traditional workflow management systems (WfMS) do not offer this functionality. Simply sharing and merging process models is often not possible, because workflow management lacks a widely accepted standard theory for workflow models.Multiple research and standardisation efforts to integrate different workflow theories have been proposed over the years. XPDL is the most widely used standard for process model interchange and supported by over 80 systems.However, XPDL also lacks the possibility to relate a workflow model to its possible choreography interface abstractions.To remedy this situation, we propose to abstract the XPDL model to a higher-level model, perform the integration and the compaction algorithms at that level and then ground it back to the desired choreography models. We develop and use an integrated ontology which is based on the XPDL standard for this purpose. To facilitate the abstraction and grounding, we present a mapping procedure to automatically translate XPDL and BPMN workflow models into this ontology. After translation, these models are annotated with a parameterised role model and other collaborative properties. We present a compaction procedure that automatically maps the annotated models into external choreography interfaces that expose only the relevant information for a particular partner collaboration. Our procedure is agnostic with respect to the target choreography model. We demonstrate our approach using WSMO choreographies which enables us to automatically generate interface models from any WfMSs that supports XPDL export.

Approximating query completeness by predicting the number of answers in DHT-based web applications

Due to the rapid development of theWeb, applications based on the P2P paradigm gain more and more interest. Recently, such systems start to evolve to adopt standard database functionalities in terms of complex query processing support. This goes far beyond simple key lookups, as provided by standard DHT systems, which makes estimating the completeness of query answers a crucial challenge. In this paper, we discuss the semantics of completeness for complex queries in P2P database systems and propose methods based on the notion of routing graphs for estimating the number of expected query answers. Further, we discuss probabilistic guarantees for the estimated values and evaluate the proposed methods through an implemented system.