The REpresentational State Transfer (REST) represents an extensible, easy and elegant architecture for accessing web-based resources. REST alone and in combination with XML is fast gaining momentum in a diverse set of web applications. REST is stateless, as is HTTP on which it is built. For many applications, this not enough, especially in the context of concurrent access and the increasing need for auditing and accountability. We present a lightweight mechanism which allows the application to control the integrity of the underlying resources in a simple, yet flexible manner. Based on an opportunistic locking approach, we show in this paper that XML does not only act as an extensible and direct accessible backend that ensures easy modifications due to the allocation of nodes, but also gives scalable possibilities to perform on-the-fly integrity verification based on the tree structure.
This paper introduces an approach to mapping relational database contents to ontologies. The current effort is motivated by the need of including into the Semantic Web volumes of web data not satisfied by current search engines. A graphical tool is developed in order to ease the mapping procedure and export enhanced ontologies linked to database entities. Moreover, queries using semantic web query languages can be imposed to the database through its connection to an ontology. Using Protege, we were able to map ontology instances into relational databases and retrieve results by semantic web query languages. The key idea is that, instead of storing instances along with the ontology terminology, we can keep them stored in a database and maintain a link to the dataset. Thus, on one hand we achieve smaller size ontologies and on the other hand we can exploit database contents harmonizing the semantic web concept with current wide-spread techniques and popular applications.
This paper presents an architecture of ontological components for the Semantic Web. Many methods and methodologies can be found in the literature. Generally, they are dedicated to particular data types like text, semistructured data, relational data, etc. Our work deals with web pages. We first study the state of the art of methodologies defined to learn ontologies from texts. Then, our architecture of ontological components for the Semantic web is defined, in order to improve knowledge discovery from the web. At least, we detail the incremental construction of the domain ontology component and we present the general conceptual model associated to it.
Adaptive websites usually change as effect of user navigational actions. Most current web engineering approaches (which consider personalization) allow to detect basic user browsing behaviour (e.g. user click on a link) but don’t consider the definition of (complex) behaviour events or user behaviour pattern recognition. In this paper, we use a method independent language called PRML to specify behaviour aware websites. PRML evolved out the experience of OO-H and was designed to be a generic personalization specification method that can be reused for different web design approaches. PRML allows the personalization when a complex behaviour event is triggered (i.e. a sequence of links) and also allows the definition and recognition (at runtime) of user behaviour patterns.
In this paper, we present our KMi semantic web portal infrastructure, which supports two important tasks of semantic web portals, namely metadata extraction and data querying. Central to our infrastructure are three components: i) an automated metadata extraction tool, ASDI, which supports the extraction of high quality metadata from heterogeneous sources, ii) an ontology-driven question answering tool, AquaLog, which makes use of the domain specific ontology and the semantic metadata extracted by ASDI to answers questions in natural language format, and iii) a semantic search engine, which enhances traditional text-based searching by making use of the underlying ontologies and the extracted metadata. A semantic web portal application has been built, which illustrates the usage of this infrastructure.
Mobile devices provide a variety of ways to access information resources available on the Web and a high level of adaptability to different aspects (e.g., device capabilities, network QoS, user preferences, location, an so on) is strongly required in this scenario. In this paper we propose a technique for the efficient adaptation of Web Information Systems. The approach relies on special rules that allows us to specify, in a declarative way, how to generate, in an automatic way, the adaptation specifications that satisfy the requirements of a given context. Rules are classified in a set of clusters and a matching relation between clusters and context requirements is defined. The technique of rule evaluation and clustering guarantee that different contexts and orthogonal requirements of adaptation, possibly not fixed in advance, can be efficiently organized and taken into account in the adaptation process.
This paper presents an approach of supporting users in formulating queries in the Semantic Web applications. We create an innovative mediator environment containing a lighter query language to help the users in the challenging task of making unambiguous requests. The query language is designed firstly for the SemanticLIFE's Virtual Query System [1] and could be used for other Semantic Web applications. The proposed query language, namely Virtual Query Language (VQL), is an effort of reducing complexity in the query formulation, especially from the user-side. Furthermore, it simplifies the communication between components of the SemanticLIFE system with the VQS, and increases the portability of the system.
A number of diverse data sources on cultural/artistic heritage, hosted by local institutions, may provide a rich collection of study material for experts in this field. Anyway, a wide exploitation of such a huge amount of information is hampered by the heterogeneity and the physical distribution of data sources. The experience presented here relates to problems and solutions found in making use of this kind of data sources within a single Web Information System that offers a framework for accessing the artistic/cultural information. In particular, design issues in dealing with metadata are discussed, as well as architectural aspects from the metadata harvesting to the presentation tier. All the system leverages the web infrastructure to cope with both organizational and technological diversity among the composing modules.
In this paper, we illustrate a preliminary approach to the translation of Web data between heterogeneous formats. This work fits into a larger project whose aim is the development of a tool for the management of data described according to a large variety of formats used on the Web and the (semi)automatic translation of schemes and instances from one model to another. Data translations operate over XML representations of instances and rely on a uniform representation of models that we call metamodel. The metamodel shows structural diversities and dictates the needed transformations. Complex translation can be derived by combining a number of predefined basic functions performing XML transformations expressed in XQuery. Practical examples are provided to show the effectiveness of the approach.
