Advances in Computers Chapter

Published by Tomas  Vitvar on April 28, 2009 in Publications,Research

Elsevier published our work on Semantic Web Services with Lightweight Descriptions of Services in its Advances in Computers, volume 76 (co-authored by me, Jacek Kopecky, Jana Viskova, Adrian Mocan, Mick Kerrigan and Dieter Fensel). In order to publish in this book, authors need to receive an invitation from Elsevier and we were glad to receive this invitation in 2008. This book’s edition is in general about semantic web, its foundations and applications such as social web.

It is nice to see that apart from our contribution, there is also a chapter from my former collegues from DERI Galway, John Breslin et al., on The Future of Social Websites: Sharing Data and Trusted Applications with Semantics.

Our Innovative B2B SOA Solution Wins €700 Prize

Published by Tomas  Vitvar on February 6, 2009 in Publications,Research

Our solution, an innovative SOA technology that we apply to solve various B2B real-world scenarios wins the prize of 700€ at the industrial track of the ASWC in Bangkok, Thailand. The development of the underlying technology (called WSMX) started in early 2004 as part of the DERI and STI R&D activities, and starting from 2006 we significantly improved the technology by solving various real-world scenarios from B2B as defined by the SWS Challenge initiative. Apart from implementation and showcasing the benefits of the technology applied to the B2B (see details here), we also have a significant number of research papers that came out from this activity:

My collaboration with Maciej Zaremba, co-architect and software engineer of the solution, turned out to be very successful: we managed not only to build the working solution for the B2B challenge scenarios but also publish the significant number of articles in very competitive research environments (acceptance rates  usually range from 15 to 20 percent).

hRESTS — a Microformat for RESTful Services

Published by Tomas  Vitvar on December 1, 2008 in Publications,Research

Our work on hRESTS, a microformat to describe RESTful services (co-authored by Jacek Kopecky, Karthik Gomadam and me) has been accepted to a Web Intelligence conference to be held in Sydney, Australia this year in December (the acceptance rate was around 18%). You can download the full paper here.

The value of today’s Web applications is no longer only in providing content to consumers but also in exposing functionality through public APIs designed for machine consumption. Typically, both Web applications and APIs today follow the Web architecture style called REST, and public APIs on the Web are often called “RESTful Web services”. The major problem with today’s RESTful APIs is that they are usually only described in a plain, unstructured HTML documentation useful only to a human developer. From this reason, finding suitable services, composing them (“mashing them up”), mediating between different data formats etc. are currently completely manual tasks.

hRESTS is a microformat for machine-readable descriptions of Web APIs, backed by a simple service model. In general, a microformat is an approach for annotating human-oriented Web pages so that key information is machine-readable. On top of microformats, GRDDL is a mechanism for extracting RDF information from Web pages, particularly suitable for processing microformats. There are already microformats for contact information, geographic coordinates, calendar events, etc.

Figure above depicts the model that the hRESTS uses for HTML annotation. It is derived from the fact that every web application using hyperlinks for linking application’s pages can be seen as a service. Obviously, not every web application can be considered as a RESTful service as it does not necessarily follow the REST architecture style. There are a lot of examples of badly designed RESTful architectures, such as here. We use RDF to represent the model that can be further extended with additional information such as WSMO-Lite service ontology (see my previous post and our paper about WSMO-Lite). In its basic form, the hRESTS annotation for a hotel service is shown below.

In order to extract the meta-data from the annotated HTML document using hRESTS, one needs to know the hRESTS annotation mechanism. For this purpose and in accordance with GRDDL we also provide a XSLT stylesheet that extracts the meta-data in RDF from XHTML pages. You can download the XSLT stylesheet here.

Once the hRESTS is used by RESTful service providers, one can easily build a focused search engine for RESTful services, for example by using Yahoo! BOSS web search in analogical way like BOSS web search can be used for e.g. searching LinkedIn public profiles annotated with hResume microformat. We further plan to submit the hRESTS microformat to as well as build extenisions towards semantic annotations which we call MicroWSMO.

Formal Model for Semantic-Driven Service Execution

Published by Tomas  Vitvar on August 8, 2008 in Publications,Research

Our work on formal model for semantic-driven service execution (co-authored by me, Adrian Mocan, and Maciej Zaremba) will be published in proceedings of the 7th International Semantic Web Conference (ISWC) to be held in Karlsruhe, Germany in November this year (acceptance rate 16%). You can access the full paper here.

In this work we define a model and an algorithm for execution of services which interfaces are modeled using Abstract State Machines (ASM) that use ontological concepts for their vocabularies (we call this description a choreography). Ontologically-enhanced ASM allows to model services’ interfaces with more descriptive information (as opposed to e.g. interfaces in WSDL only defining a set of operations with input and output messages and message exchange patterns for those operations). In this work we build additional layer of ASM descriptions on top of WSDL descriptions (XML Schema and Interface) and show how a conversation between two services can be executed.

The important aspect of service execution is to maintain services’ interoperability at the data and process levels. Data interoperability needs to be ensured when services use different information models used to define services’ input and output messages, and process interoperability needs to be ensured when one service expects to exchange messages in an order that is not directly matching the order of the other service. We illustrate the usage of the execution model on the case scenario implemented on our WSMO, WSML, and WSMX technologies as the figure below depicts.

The scenario describes a mediation problem defined by the SWS Challenge initiative. In the scenario, a trading company, called Moon, uses a Customer Relationship Management system (CRM) and an Order Management System (OMS) to manage its order processing. Moon has signed agreements to exchange Purchase Order (PO) messages with a company called Blue using the RosettaNet standard PIP3A4. There are two interoperability problems in the scenario: At the data level, the Blue uses PIP3A4 to define the PO request and confirmation messages while Moon uses a proprietary XML Schema for its OMS and CRM systems. At the process level, the Blue follows PIP3A4 Partner Interface Protocol (PIP), i.e. it sends out a PIP3A4 PO message, including all items to be ordered, and expects to receive a PIP3A4 PO confirmation message. On the other hand, various interactions with the CRM and OMS systems must be performed in Moon in order to process the order, i.e. get the internal ID for the customer from the CRM system, create the order in the OMS system, add line items into the order, close the order, and send back the PO confirmation.

By using ASMs and ontologies we automatically adjust the order of messages conforming to both services’ descriptions while at the same time we resolve data interoperability conflicts by using ontology alignments between services’ information models. The following Figure depicts the model in a form of a state diagram.

In our paper we describe in detail the algorithm for services execution operating according to the model depicted in the figure above. The input for the algorithm are two services both having defined their choreographies as ontologized ASMs over WSDL interface operations (in addition, a grounding between ASM rules and underlying WSDL interface operations is also defined), and ontology alignments between both services’ ontologies. In a nuthshell, when a message is available from one service, the algorithm process the message, that is, it transforms the message to the others service’s ontology and places the message for evaluation by its choreography.

It is important to note, that our algorithm works well in cases when the two choreographies are compatible, that is, interoperability can be achieved by adjusting the order of messages. The algorithm in its current form will not work when there is a message requested by one service that the other service never sends. In such cases, the message would have to be created on the fly based on some background knowledge that the algorithm should posses while at the same time solutions for such problems would need to build on a concrete semantics of messages. For example, the algorithm should know that a message is an acknowledgment message, etc. These questions remain open for our future research.

Planned Book on Semantic Technologies for E-Government

Published by Tomas  Vitvar on July 29, 2008 in Publications,Research

Our proposal for the book entitled “Semantic Technologies for E-Government: An European Perspective” has been accepted by Springer and we are currently in process of signing a contract. This is the edited book having three editors, Vassilios Peristeras (DERI, Galway, Ireland), Tomas Vitvar (STI Innsbruck, Austria) and Konstantinos Tarabanis (CERTH, Thessaloniki, Greece).

The goal of the book will be to describe current status of research and development in e-government empowered by semantic technologies, mainly done in the context of the EU-funded R&D projects. There is a number of contributing authors to this book that include researchers and practitioners from academia and industry around Europe. In addition, we will have an overview of activities in the US.

Apart from the book editing, we will also contribute to the book with major results of our EU FP6 SemanticGov project. In particular, we will describe an architecture for integration of cross-border e-government services based on the Semantic Web Services architecture and Public Administration ontology based on the Web Service Modeling Ontology (WSMO) conceptual model called WSMO-PA.

The book should be available in mid of 2009.

WSMO-Lite at ESWC 2008

Published by Tomas  Vitvar on April 25, 2008 in Publications,Research

WSMO-Lite, which describes a lightweight service ontology and annotation mechanism for Web Service Description Language (WSDL), has been accepted for the European Semantic Web Conference 2008 (you can download the paper here).

WSMO-Lite which is currently under the review process in the CMS WG, has been co-authored by Tomas Vitvar, Jacek Kopecky, Jana Viskova and Dieter Fensel. In the paper we define the service ontology describing constructs for services’ information model (ontology) as well as functional services’ descriptions (i.e., categorization, conditions and effects). Using the W3C Semantic Annotations for WSDL and XML Schema (SAWSDL), we define a mechanism for annotation of various WSDL components with WSMO-Lite semantic descriptions. In addition, we define the algorithm to derive the behavioral service descriptions in a form of Abstract State Machines (ASM) from functional annotations (i.e. conditions and effects) of WSDL interface operations and we outline a usage of semantic annotations for a number of services’ use tasks such as service discovery, composition, selection, mediation, etc.

SAWSDL: Semantic Annotations for WSDL and XML Schema

Published by Tomas  Vitvar on November 2, 2007 in Publications,Research

In November/December, IEEE Internet Computing magazine published our article on the Semantic Annotations for WSDL and XML Schema (SAWSDL). In this article we summarize the results of the W3C SAWSDL Wokring Group.

SAWSDL is the first step in W3C toward standardizing technologies for Semantic Web services. As a standard, SAWSDL provides a common ground for the various ongoing efforts toward SWS frameworks, such as the Web Service Modeling Ontology (WSMO) and the OWL-based Web Service Ontology (OWL-S). SAWSDL extends the major Web service technology WSDL with pointers to semantics that are crucial for achieving automation.

SESA: Emerging Technology for Service-Centric Environments

Published by Tomas  Vitvar on October 18, 2007 in Publications,Research

The IEEE Software magazine published in the November/December issue our article entitled SESA: Emerging Technology for Service-Centric Environments where we discuss the innovative SOA technology based on the semantic service descriptions. We first outline a number of governing principles for the SESA design, research and implementation such as the service-oriented principle, the semantic principle, and the problem-solving principle. Following these principles, the SESA defines a set of essential functionalities (middleware services) required for the automation of the service provisioning process such as discovery, adaptation, fault handling, monitoring, mediation, and so on. The important aspect of the SESA lies in the semantic description of business services. The SESA adopts the semantic model introduced by WSMO (Web Service Modeling Ontology) extending WSDL service descriptions with semantics for information model, functional service definitions, behavioral descriptions and non-functional properties. We discuss in detail all these service semantics and illustrate their use on number of examples. In addition, we describe the business services integration process facilitated by the SESA middleware services composed of so called late-binding phase and execution phase.

Our work on the SESA has been done in the context of the EU project Knowledge Web, OASIS Semantic Execution Environment Technical Committee, roadmap for the research agenda of the European Technology Platform NESSI (its Semantic Technology working group), and STi2 initiative. The future direction of this work will be to integrate the SESA platform with major enterprise technologies and to expand the SESA towards large-scale SOA on the Web. Both these directions will be subject of research and development in the upcoming Irish and the EU projects, namely Lion, COIN and SOA4ALL.