A layered framework supporting personal information integration and application design for the semantic desktop
The VLDB journal
With the development of inexpensive storage devices, space usage is no longer a bottleneck for computer users. However, the increasingly large amount of personal information poses a critical problem to those users: traditional file organization in hierarchical directories may not be suited to the effective management of personal information because it ignores the semantic associations therein and bears no connection with the applications that users will run. To address such limitations, we
... nt our vision of a semantic desktop, which relies on the use of ontologies to annotate and organize data and on the concept of personal information application (PIA), which is associated with a user's task. The PIA designer is the tool that is provided for building a variety of PIAs consisting of views (e.g., text, list, table, graph), which are spatially arranged and display interrelated fragments of the overall personal information. The semantic organization of the data follows a layered architecture that models separately the personal information, the domain data, and the application data. The network of concepts that ensues from extensive annotation and explicit associations lends itself well to rich browsing capabilities and to the formulation of expressive databaselike queries. These queries are also the basis for the interaction among views of the PIAs in the same desktop or in networked desktops. In the latter case, the concept of desktop service provides for a semantic platform for the integration of information across different desktops and the web. In this paper, we present in detail the semantic organization of the information, the overall system architecture and implementation aspects, queries and their processing, PIAs and the PIA designer, including usability studies on the designer, and the concepts of semantic navigation in a desktop and of interoperation in a network of desktops. (Web Information Systems Engineering) conference and the WISE (Women in Science and Engineering) initiative-a case of semantic heterogeneity. In the semantic desktop approach, as in the semantic web, a major role is played by ontologies that give meaning to data. Given the data associated with an application, also called domain, a domain ontology contains a conceptual description of that data, consisting of the concepts used, their attributes, and the relationships between those concepts. For example, the Resource Description Framework, RDF, 2 is based on resources, which correspond to concepts and on properties that correspond to attributes or to relationships between concepts. We further use the vocabulary language for RDF, the RDF Schema (RDFS). 3 By using RDFS we can assert, for example, that a resource is a subclass of another resource or the range of a property. The semantic desktop vision consists of assuming that "all digital information items stored on a PC can be seen as web resources to which the RDF model can be applied."  . This vision also includes the concept of peer-to-peer (P2P) communication between applications in distributed desktops or within the same desktop. The advantage of this form of communication is that it is completely decentralized with all the applications being able to communicate with one another using the same protocol independently of where they reside. Example 2. When modeling the Bibliography domain, an ontology will have resource Publication and its subclasses (also resources), which include Journal and Conference Proceedings. Publication has properties such as Title, Written by, and Year. The range of Written by is the resource Author, which in turn has several properties, including Name, whose range is the resource Literal.