Showing papers on "Semantic Web Stack published in 2001"

DAML-S: semantic markup for web services

Abstract: The Semantic Web should enable greater access not only to content but also to services on the Web. Users and software agents should be able to discover, invoke, compose, and monitor Web resources offering particular services and having particular properties. As part of the DARPA Agent Markup Language program, we have begun to develop an ontology of services, called DAML-S, that will make these functionalities possible. In this paper we describe the overall structure of the ontology, the service profile for advertising services, and the process model for the detailed description of the operation of services. We also compare DAML-S with several industry efforts to define standards for characterizing services on the Web.

Semantic Web services

Abstract: The authors propose the markup of Web services in the DAML family of Semantic Web markup languages. This markup enables a wide variety of agent technologies for automated Web service discovery, execution, composition and interoperation. The authors present one such technology for automated Web service composition.

Resource description framework: metadata and its applications

Abstract: Universality, the property of the Web that makes it the largest data and information source in the world, is also the property behind the lack of a uniform organization scheme that would allow easy access to data and information. A semantic web, wherein different applications and Web sites can exchange information and hence exploit Web data and information to their full potential, requires the information about Web resources to be represented in a detailed and structured manner. Resource Description Framework (RDF), an effort in this direction supported by the World Wide Web Consortium, provides a means for the description of metadata which is a necessity for the next generation of interoperable Web applications. The success of RDF and the semantic web will depend on (1) the development of applications that prove the applicability of the concept, (2) the availability of application interfaces which enable the development of such applications, and (3) databases and inference systems that exploit RDF to identify and locate most relevant Web resources. In addition, many practical issues, such as security, ease of use, and compatibility, will be crucial in the success of RDF. This survey aims at providing a glimpse at the past, present, and future of this upcoming technology and highlights why we believe that the next generation of the Web will be more organized, informative, searchable, accessible, and, most importantly, useful. It is expected that knowledge discovery and data mining can benefit from RDF and the Semantic Web.

Creating Semantic Web contents with Protege-2000

Abstract: As researchers continue to create new languages in the hope of developing a Semantic Web, they still lack consensus on a standard. The authors describe how Protege-2000, a tool for ontology development and knowledge acquisition, can be adapted for editing models in different Semantic Web languages.

Agents and the Semantic Web

Abstract: Many challenges of bringing communicating multi-agent systems to the World Wide Web require ontologies. The integration of agent technology and ontologies could significantly affect the use of Web services and the ability to extend programs to perform tasks for users more efficiently and with less human intervention.

OIL: an ontology infrastructure for the Semantic Web

Abstract: Researchers in artificial intelligence first developed ontologies to facilitate knowledge sharing and reuse. Ontologies play a major role in supporting information exchange across various networks. A prerequisite for such a role is the development of a joint standard for specifying and exchanging ontologies. The authors present OIL, a proposal for such a standard. Ontologies applied to the World Wide Web are creating the Semantic Web.

Annotea: an open RDF infrastructure for shared Web annotations

Abstract: Annotea is a Web-based shared annotation system based on a general-purpose open RDF infrastructure, where annotations are modeled as a class of metadata. Annotations are viewed as statements made by an author about a Web document. Annotations are external to the documents and can be stored in one or more annotation servers. One of the goals of this project has been to re-use as much existing W3C technology as possible. We have reached it mostly by combining RDF with XPointer, XLink, and HTTP. We have also implemented an instance of our system using the Amaya editor/browser and a generic RDF database, accessible through an Apache HTTP server. In this implementation, the merging of annotations with documents takes place within the client. The paper presents the overall design of Annotea and describes some of the issues we have faced and how we have solved them.

Crawling the Hidden Web

Abstract: Current-day crawlers retrieve content only from the publicly indexable Web, i.e., the set of Web pages reachable purely by following hypertext links, ignoring search forms and pages that require authorization or prior registration. In particular, they ignore the tremendous amount of high quality content “hidden” behind search forms, in large searchable electronic databases. In this paper, we address the problem of designing a crawler capable of extracting content from this hidden Web. We introduce a generic operational model of a hidden Web crawler and describe how this model is realized in HiWE (Hidden Web Exposer), a prototype crawler built at Stanford. We introduce a new Layout-based Information Extraction Technique (LITE) and demonstrate its use in automatically extracting semantic information from search forms and response pages. We also present results from experiments conducted to test and validate our techniques.

System and method for creating a semantic web and its applications in browsing, searching, profiling, personalization and advertising

Abstract: A system and method for creating a database of metadata (metabase) [14] of a variety of digital media content, including TV and radio content delivered on Internet. This semantic-based method captures and enhances domain or subject specific metadata of digital media content, including the specific meaning and intended use of original content, including the specific meaning and intended use of original content. To support semantics, a WorldModel [11] is provided that includes specific domain knowledge, ontologies as well as a set of rules relevant to the original content. The metabase [14] may also be dynamic in that it may track changes to the any variety of accessible content, including live and archival TV and radio programming.

Anchor-PROMPT: Using Non-Local Context for Semantic Matching.

Abstract: Researchers in the ontology-design field have developed the content for ontologies in many domain areas. Recently, ontologies have become increasingly common on the WorldWide Web where they provide semantics for annotations in Web pages. This distributed nature of ontology development has led to a large number of ontologies covering overlapping domains, which researchers now need to merge or align to one another. The processes of ontology alignment and merging are usually handled manually and often constitute a large and tedious portion of the sharing process. We have developed and implemented Anchor-PROMPT—an algorithm that finds semantically similar terms automatically. Anchor-PROMPT takes as input a set of anchors—pairs of related terms defined by the user or automatically identified by lexical matching. AnchorPROMPT treats an ontology as a graph with classes as nodes and slots as links. The algorithm analyzes the paths in the subgraph limited by the anchors and determines which classes frequently appear in similar positions on similar paths. These classes are likely to represent semantically similar concepts. Our experiments show that when we use Anchor-PROMPT with ontologies developed independently by different groups of researchers, 75% of its results are correct. 1 Ontology Merging and Anchor-PROMPT Researchers have pursued development of ontologies— explicit formal specifications of domains of discourse—on the premise that ontologies facilitate knowledge sharing and reuse (Musen 1992; Gruber 1993). Today, ontology development is moving from academic knowledgerepresentation projects to the world of e-commerce. Companies use ontologies to share information and to guide customers through their Web sites. The ontologies on the World-Wide Web range from large taxonomies categorizing Web sites (such as on Yahoo!) to categorizations of products for sale and their features (such as on Amazon.com). The WWW Consortium is developing the Resource Description Framework (Brickley and Guha 1999), a language for encoding semantic information on Web pages in machine-readable form. Such encoding makes it possible for electronic agents searching for information to share the common understanding of the semantics of the data represented on the Web. Many disciplines now develop standardized ontologies that domain experts can use to share and annotate information in their fields. Medicine, for example, has produced large, standardized, structured vocabularies such as SNOMED (Price and Spackman 2000) and the semantic network of the Unified Medical Language System (Humphreys and Lindberg 1993). With this widespread distributed use of ontologies, different parties inevitably develop ontologies with overlapping content. For example, both Yahoo! and the DMOZ Open Directory (Netscape 1999) categorize information available on the Web. The two resulting directories are similar, but also have many differences. Currently, there are extremely few theories or methods that facilitate or automate the process of reconciling disparate ontologies. Ontology management today is mostly a manual process. A domain expert who wants to determine a correlation between two ontologies must find all the concepts in the two source ontologies that are similar to one another, determine what the similarities are, and either change the source ontologies to remove the overlaps or record a mapping between the sources for future reference. This process is both labor-intensive and error-prone. The semi-automated approaches to ontology merging that do exist today (Section 2) such as PROMPT and Chimaera analyze only local context in ontology structure: given two similar classes, the algorithms consider classes and slots that are directly related to the classes in question. The algorithm that we present here, Anchor-PROMPT, uses a set of heuristics to analyze non-local context. The goal of Anchor-PROMPT is not to provide a complete solution to automated ontology merging but rather to augment existing methods, like PROMPT and Chimaera, by determining additional possible points of similarity between ontologies. Anchor-PROMPT takes as input a set of pairs of related terms—anchors—from the source ontologies. Either the user identifies the anchors manually or the system generates them automatically. From this set of previously identified anchors, Anchor-PROMPT produces a set of new pairs of semantically close terms. To do that, Anchor-PROMPT traverses the paths between the anchors in the corresponding ontologies. A path follows the links between classes defined by the hierarchical relations or by slots and their domains and ranges. Anchor-PROMPT then compares the terms along these paths to find similar terms. For example, suppose we identify two pairs of anchors: classes A and B and classes H and G (Figure 1). That is, a class A from one ontology is similar to a class B in the other ontology; and a class H from the first ontology is similar to a class G from the second one. Figure 1 shows one path from A to H in the first ontology and one path from B to G in the second ontology. We traverse the two paths in parallel, incrementing the similarity score between each two classes that we reach in the same step. For example, after traversing the paths in Figure 1, we increment the similarity score between the classes C and D and between the classes E and F. We repeat the process for all the existing paths that originate and terminate in the anchor points, cumulatively aggregating the similarity score. The central observation behind Anchor-PROMPT is that if two pairs of terms from the source ontologies are similar and there are paths connecting the terms, then the elements in those paths are often similar as well. Therefore, from a small set of previously identified related terms, AnchorPROMPT is able to suggest a large number of terms that are likely to be semantically similar as well. Figure 1. Traversing the paths between anchors. The rectangles represent classes and labeled edges represent slots that relate classes to one another. The left part of the figure represents classes and slots from one ontology; the right part represents classes and slots from the other. Solid arrows connect pairs of anchors; dashed arrows connect pairs of related terms.

eLearning based on the semantic web

Abstract: eLearning is fast, relevant and just-in-time learning grown from the learningrequirements of the new, dynamically changing, distributed business world. The term „Semantic Web” encompasses efforts to build a new WWW architecture that supports content with formal semantics, which enables better possibilities for searching and navigating through the cyberspace. As such, the Semantic Web represents a promising technology for realizing eLearning requirements. This paper presents an approach for implementing the eLearning scenario using Semantic Web technologies. It is primarily based on ontology-based descriptions of content, context and structure of the learning materials and benefits the providing of and accessing to the learning materials.

Publishing on the semantic web

Abstract: The coming Internet revolution will profoundly affect scientific information.

The Role of Frame-Based Representation on the Semantic Web

Abstract: We believe that to build the Semantic Web, the sharing of ontological information is required. This allows agents to reach partial shared understanding and thus interoperate. We are proposing frame-based representation as a suitable paradigm for building ontologies as well as the World Wide Web Consortium's RDF-formalism (and its extensions, such as the DARPA Agent Markup Language) as a manifestation of frame-based representation for the Web.

HTML page analysis based on visual cues

Abstract: We present an approach to automatically analyzing semantic structure of HTML pages based on detecting visual similarities of content objects on Web pages. The approach is developed based on the observation that in most Web pages, layout styles of subtitles or records of the same content category are consistent and there are apparent separation boundaries between different categories. Thus these subtitles should have similar appearances if they are rendered in visual browsers and different categories can be separated clearly In our approach we first measure visual similarities of HTML content objects. Then we apply a pattern detection algorithm to detect frequent patterns of visual similarity and use a number of heuristics to choose the most possible patterns. By grouping items according to these patterns, we finally build a hierarchical representation (tree) of an HTML document with "visual consistency" inferred semantics. Preliminary experimental results show promising performances of the method with real Web pages.

A New Portrait of the Semantic Web in Action

Abstract: Without semantically enriched content, the Web cannot reach its full potential. The authors discuss tools and techniques for generating and processing such content, thus setting a foundation upon which to build the Semantic Web. The authors put a Semantic Web language through its paces and answer questions about how people can use it, such as: how do authors generate semantic descriptions; how do agents discover these descriptions; how can agents integrate information from different sites; and how can users query the Semantic Web.

A semantic web approach to service description for matchmaking of services

Abstract: Matchmaking is an important aspect of e-commerce interactions. Advanced matchmaking services require rich and flexible metadata that are not supported by currently available industry standard frameworks for e-commerce such as UDDI and ebXML. The semantic web initiative at W3C is gaining momentum and generating technologies and tools that might help bridge the gap between the current standard solutions and the requirement for advanced matchmaking services. In this paper we examine the problem of matchmaking, highlighting the features that a matchmaking service should exhibit and deriving requirements on metadata for description of services from a matchmaking point of view. We then assess a couple of standard frameworks for e-commerce against these requirements. Finally, we report on our experience of developing a semantic web based matchmaking prototype. In particular, we present our views on usefulness, adequacy, maturity and tool support of semantic web related technologies such as RDF and DAML.

Enabling dynamic content caching for database-driven web sites

Abstract: Web performance is a key differentiation among content providers. Snafus and slowdowns at major web sites demonstrate the difficulty that companies face trying to scale to a large amount of web traffic. One solution to this problem is to store web content at server-side and edge-caches for fast delivery to the end users. However, for many e-commerce sites, web pages are created dynamically based on the current state of business processes, represented in application servers and databases. Since application servers, databases, web servers, and caches are independent components, there is no efficient mechanism to make changes in the database content reflected to the cached web pages. As a result, most application servers have to mark dynamically generated web pages as non-cacheable. In this paper, we describe the architectural framework of the CachePortal system for enabling dynamic content caching for database-driven e-commerce sites. We describe techniques for intelligently invalidating dynamically generated web pages in the caches, thereby enabling caching of web pages generated based on database contents. We use some of the most popular components in the industry to illustrate the deployment and applicability of the proposed architecture.

Extending UML for modeling Web applications

Abstract: Web sites are progressively evolving from browsable, read-only information repositories to Web-based distributed applications. Compared to traditional Web sites, these Web applications do not only support navigation and browsing, but also operations that affect their contents and navigation states. Compared to traditional applications Web applications integrate operations with the built-in browsing capabilities of hypermedia. These novelties make Web application design a complex task that requires the integration of methods and techniques developed in different "worlds". This integration is achieved in this paper by extending and customizing the Unified Modeling Language (UML) with Web design concepts borrowed from the Hypermedia Design Model (HDM). Hypermedia elements are described through appropriate UML stereotypes. UML diagrams are also tailored to model operations and relate them with hypermedia elements. The approach is exemplified by describing the design of a Web-based conference manager.

DReggie: Semantic Service Discovery for M-Commerce Applications

Abstract: The emergence of mobile devices and wireless networks has created a new path in the field of e-commerce: ``m-commerce''. Significant research needs to be done in the field of service discovery to support m-commerce applications. Various new applications, that would use services available to a mobile device from both the fixed network backbone and peer mobile devices in its proximity, are being developed. M-commerce applications have the challenging task of discovering services in a dynamically changing environment. To support dynamic service discovery, existing mechanisms need to move beyond trivial attribute or interface matching. Recently the DARPA Agent Markup Language (DAML) has been developed to semantically describe the content of the web. In this paper, we describe ongoing work in developing a dynamic service discovery infrastructure using DAML. This architecture is built on the Jini service discovery framework. Our service discovery infrastructure can find services in a semantically richer way, instead of using simple attribute or interface based matching. This increased flexibility in service discovery has the potential to enable a broad range of m-commerce applications.

SEAL: a framework for developing SEmantic PortALs

Abstract: The core idea of the Semantic Web is to make information accessible to human and software agents on a semantic basis. Hence, Web sites may feed directly from the Semantic Web exploiting the underlying structures for human and machine access. We have developed a domain-independent approach for developing semantic portals, viz. SEAL (SEmantic portAL), that exploits semantics for providing and accessing information at a portal as well as constructing and maintaining the portal. In this paper we focus on semantics-based means that make semantic Web sites accessible from the outside, i.e. semantics-based browsing, semantic querying, querying with semantic similarity, and machine access to semantic information. In particular, we focus on methods for acquiring and structuring community information as well as methods for sharing information.As a case study we refer to the AIFB portal - a place that is increasingly driven by Semantic Web technologies. We also discuss lessons learned from the ontology development of the AIFB portal..

AeroDAML: Applying Information Extraction to Generate DAML Annotations from Web Pages.

Abstract: The DARPA Agent Markup Language (DAML) is an emerging knowledge representation for the Semantic Web. DAML can encode the semantics of a document for use by agents on the web. However, DAML annotation of documents and web pages is a tedious and time consuming task. AeroDAML is a knowledge markup tool that applies natural language information extraction techniques to automatically generate DAML annotations from web pages. AeroDAML links most proper nouns and common relationships with classes and properties in DAML ontologies. This paper discusses the design of AeroDAML including linguistic and practical issues related to semantic annotation.

Semantic annotation and transcoding: making Web content more accessible

Abstract: We propose a method for constructing superstructure on the Web using XML and external annotations to Web documents. We have three approaches for annotating documents: linguistic, commentary, and multimedia. The result is annotated documents that computers can understand and process more easily, allowing content to reach a wider audience with minimal overhead.

Ontology Merging for Federated Ontologies for the Semantic Web

Abstract: One of the core challenges for the Semantic Web is the aspect of decentralization. Local structures can be modeled by ontologies. However, in order to support global communication and knowledge exchange, mechanisms have to be developed for integrating the local systems. We adopt the database approach of autonomous federated database systems and consider an architecture for federated ontologies for the Semantic Web as starting point of our work. We identify the need for merging specific ontologies for developing federated, but still autonomous web systems. We present the method FCA–MERGE for merging ontologies following a bottom-up approach which offers a structural description of the merging process. The method is guided by application-specific instances of the given source ontologies that are to be merged. We apply techniques from natural language processing and formal concept analysis to derive a lattice of concepts as a structural result of FCA–MERGE. The generated result is then explored and transformed into the merged ontology with human interaction.

Retrieving and organizing web pages by “information unit”

Abstract: Since WWW encourages hypertext and hypermedia document authoring (e.g., HTML or XML), Web authors tend to create documents that are composed of multiple pages connected with hyperlinks or frames. A Web document may be authored in multiple ways, such as (1) all information in one physical page, or (2) a main page and the related information in separate linked pages. Existing Web search engines, however, return only physical pages. In this paper, we introduce and describe the use of the concept of information unit, which can be viewed as a logical Web document consisting of multiple physical pages as one atomic retrieval unit. We present an algorithm to eAEciently retrieve information units. Our algorithm can perform progressive query processing over a Web index by considering both document semantic similarity and link structures. Experimental results on synthetic graphs and real Web data show the effectiveness and usefulness of the proposed information unit retrieval technique.

The semantic web: a brain for humankind

Abstract: At a recent colloquium, a speaker referred to a "science fiction vision" that consisted of sets of agents running around the Web performing complex actions for their users. He argued that we were far from the day when this would be real and that the infrastructure was not in place to make this happen. While his latter assessment is accurate, the former is far too pessimistic. Furthermore, a crucial component of this infrastructure, a "standardized" Web ontology language, is starting to emerge. In this article, the author provides a few pointers to this emerging area and shows how the ontology languages of the Semantic Web can lead directly to more powerful agent-based approaches to using services offered on the Web-that is, to the realization of that speaker's "science fiction" vision.

Towards a principled approach to semantic interoperability

Abstract: Semantic interoperability is the faculty of interpreting knowledge imported from other languages at the semantic level, i.e. to ascribe to each imported piece of knowledge the correct interpretation or set of models. It is a very important requirement for delivering a worldwide semantic web. This paper presents preliminary investigations towards developing a unified view of the problem. It proposes a definition of semantic interoperability based on model theory and shows how it applies to already existing works in the domain. Then, new applications of this definition to family of languages, ontology patterns and explicit description of semantics are presented.

Learning of Ontologies from the Web: the Analysis of Existent Approaches.

Abstract: The next generation of the Web, called Semantic Web, has to improve the Web with semantic (ontological) page annotations to enable knowledge-level querying and searches. Manual construction of these ontologies will require tremendous efforts that force future integration of machine learning with knowledge acquisition to enable highly automated ontology learning. In the paper we present the state of the-art in the field of ontology learning from the Web to see how it can contribute to the task of semantic Web querying. We consider three components of the query processing system: natural language ontologies, domain ontologies and ontology instances. We discuss the requirements for machine learning algorithms to be applied for the learning of the ontologies of each type from the Web documents, and survey the existent ontology learning and other closely related approaches.

Mobilizing the semantic web with DAML-enabled web services

Abstract: The Web is evolving from a repository for text and images to a provider of services - both information-providing services, and services that have some effect on the world. Today's Web was designed primarily for human use. To enable reliable, large-scale automated interoperation of services by computer programs or agents, the properties, capabilities, interfaces and effects of Web services must be understandable to computers. In this paper we propose a vision and a partial realization of precisely this. We propose markup of Web services in the DAML family of semantic Web markup languages. Our markup of Web services enables a wide variety of agent technologies for automated Web service discovery, execution, composition and interoperation. We present one logic-based agent technology for service composition, predicated on the use of reusable, task-specific, high-level generic procedures and user-specific customizing constraints.