An RDF Editor and Portal for the Semantic Web Aditya Kalyanpur and Jennifer Golbeck and Michael Grove and Jim Hendler 1 1 ABSTRACT1 3 RDF EDITOR AND SEMANTIC WEB RDF is emerging as one of the main languages for PORTAL creating semantic markup on the web. The RDF Editor combines WYSIWIG HTML editing with a semantic The goal of the RDF Editor is fourfold: web portal for guided semantic markup using distributed vocabularies. Instead of serving as a 1. To provide the user with a flexible environment platform for developing vocabularies and in which he can create his web page with few relationships, this editor is designed to provide a markup hindrances simple interface for users to add RDF to their HTML 2. To allow the user to markup with minimal documents as they are created. Users can search online knowledge of RDF terms and syntax repositories for existing ontologies to borrow terms for 3. To provide a reference to existing ontologies on use in their own documents. This paper describes the the internet for use in the markup implementation and interface features of the tool. 4. To ensure accurate and complete RDF with the ability to make modifications easily 2 INTRODUCTION For someone adding semantic markup to a webpage, The current World Wide Web began and evolved as a many potential tasks exist: searching for and using mechanism for presenting data to human users. While existing ontologies, extending those ontologies, people can easily understand the concepts within a creating new ontologies, and linking the marked up document, it is currently very difficult for machines to page to others online once the RDF markup in extract any knowledge from a page. The Semantic generated. While some tools exist for each of these Web allows users to create precise, unambiguous individual tasks,, the RDF Editor is provides all these encodings of information in a machine-readable form. functions in an easy to use interface while introducing This promises to lead to many advances in the services new features.. and tools available to web users. Below, we describe each of the features of the RDF RDF (Resource Description Framework) is emerging Editor and how they help facilitate the tasks just as one of the primary languages for encoding semantic described. material on the web. To encourage web users to semantically markup their documents, we need a tool that will allow them to easily describe the knowledge 4.1 Text/RDF Editor Window that is being presented without forcing them to learn The Text/RDF editor window works in three modes to RDF. address the different needs of users. In this paper, we present the RDF Editor, a graphical Display Mode: In this mode, the window acts as a tool for creating RDF within an HTML document. basic WYSIWYG HTML editor in which the user can There are many excellent tools available that allow enter text and insert images. Users can automatically users to manage and create vocabularies. The purpose generate HTML here, or use the window for its RDF of this tool is different. The design encourages the use editing purpose: to provide semantic classification. of existing ontologies by providing features to search and manage the outside references. While users are Using one of four keyboard shortcuts, the user can creating HTML, they can quickly indicate words and quickly classify any word. The word immediately next phrases to be included in the RDF (as classes, objects, to the cursor is entered as Class, Object, Property, or properties, or values). The software automatically Value. generates the correct RDF for the relationships expressed, and in the end, the users can save the RDF If the user employs one of the shortcut keys, the to its own file or include it within their HTML window enters a value insertion mode. This mode document. provides the user with another set of shortcuts that can be keyed in to properly establish the relationship 1 between the selected term and its place within the University of Maryland, College Park, Maryland RDF structure. Information and Network Dynamics Lab Semantic Web Agent Project (MIND SWAP), A.V. Williams Building, College Park, MD, USA, email: adityakl@yahoo.com, HTML Source Mode: In this mode, the source HTML golbeck@cs.umd.edu, mhgrove@wam.umd.edu, code is displayed for editing. Users can paste in pre- hendler@cs.umd.edu written HTML code or hand code their own pages. To preview the HTML or to tag terms for inclusion in the pressing shortcut key for Properties will directly RDF, the user can enter Display Mode. insert the word “behavior” into the Property List as a property of element RDF Mode: In this mode, the RDF markup is AquaticOrganism:caddisfly larvae. displayed. The dataset specified by the user along with 2. Shortcut keys to insert Unassociated Objects, references from web ontologies/properties are used to Properties, and Values to the lists. Any construct the RDF. Users can view or edit the unassociated element is automatically associated generated RDF here. with the explicitly defined element that is added next. 4.2. Ontology Browser 3. To use an ontology from the local database, the A particularly innovative feature of the RDF Editor is user can select the appropriate class or property that it encourages users to work with multiple from the Ontology List and click on a button to ontologies. Many existing tools allow users to create transfer it to the Class or Property List. Thus, the their own ontologies for use in RDF documents. This user can either replace the class and property tool encourages users to work with and extend pre- names used in his document with existing existing ontologies, exploiting the distributed nature of ontology names and their properties or the Semantic Web. The ontology browser is the first alternatively submit them as part of a new part of the tool that support that. ontology. This interface allows the user to browse through 4.5 RDF Instance Creator existing ontologies on the Internet with the aim of finding relevant terms and properties. The default The RDF Instance Creator (RIC) is a tool designed to starting page is the DAML Ontology web site: ease the process of marking up data. RIC allows the (http://www.daml.org/ontologies) from where the user user to generate RDF simply by filling a series of could issue search queries using Class/Property names forms. The intent is to free the user from needing to as keys. Once the appropriate ontology has been know RDF while still providing all the benefits that it located, the user can add it to the local database, and has to offer. the properties of the ontology are automatically added to the Local Ontology Information where it can be RIC can use any valid ontology that is currently managed. accessible through the Internet. RIC is incorporated to the RDF Editor as an alternative method for creating 4.3 Local Ontology Information instances. By selecting the appropriate ontology from This is the second feature of this tool that supports the the Local Ontology Information window, the user adds use of multiple ontologies. This window shows the it to the RIC active data area. URI of all ontologies currently in use in the local document. For a selected ontology, a list of its classes Selecting an object from the active data area brings its and properties is also displayed. properties up in the workspace. The workspace provides a simple form interface where the user enters This window is used only for managing the ontologies data for each of the object’s properties. Some error and terms of interest. If a user wants to create an checking is also built in. For example, a field has an instance of a borrowed class, or to otherwise use integer range, the user cannot enter "3.2" or "two." classes and properties defined in an outside ontology, he can click the term of interest and include it in the 4.6 Semantic Web Portal appropriate place in the semantics of the current document. This makes the term appear in the Textual The Semantic Web Portal is a prototype for what will Semantics List become far more than just a Semantic Web search engine. Content creators can submit pages which are 4.4 Textual Semantics List indexed by their semantic markup. To search in the Semantic Web Portal, users select an ontology and The Textual Semantics window has four lists (Classes, term, and run a search for any page that is indexed by Objects, Properties, and Values) that display the that term. The portal returns a list of marked up web semantic elements of the text as marked up by the pages that describe the term, giving an individual user user. The following features are provided: the ability to see how other people relate to the same concept in the World Wide Web. For example, if the 1. Shortcut keys to insert Classes, Objects, user is writing a web page about a “Fish”, searching in Properties and Values directly into the hierarchy - the Semantic Web Portal would give him a wealth of For instance, consider the example in Figure 1. If information about “fish” defined by other end users the user’s cursor is next to the word “behavior: in from which he could borrow ideas, qualitative and the text, the selected element in the Class List is quantitative data. “AquaticOrganism”, and the selected element in the Object List is “”cassisfly larvae”, then Figure 1: The RDF Editor Interface Figure 2: The RDF Instance Creator Incorporating this tool into the RDF Editor provides that is a barrier to entry. The RDF Editor integrates a several new functionalities. First, the user can quickly wealth of features into one software package, and submit his marked up page for indexing from the tool. introduces many new features that are unavailable Perhaps more importantly, as the user includes a term anywhere else. By creating an easy to use and highly from an ontology, the Semantic Web Portal useful tool for creating RDF for individual HTML automatically can provide references to other documents, we believe that everyday users will be documents that use that same term. If the user includes more likely to use and benefit from the semantic web. the term “fish” from an ontology, the portal may provide a link to a picture of a fish. If the user decides Demos of this project and others and be found on the to borrow that picture, the portal can also make a note MIND SWAP website at http://www.mindswap.org. of the link between the two documents. REFERENCES 5 CONCLUSIONS [1] Brickley, D and R.V. Guha, “Resource The expansion of the current web provides a valuable Description Framework (RDF) Model and Syntax lesson to researchers interested in expanding the Specification”, W3C Recommendation submitted semantic web. In the early 1990’s, content on the web 22 February 1999, has to be hand coded in HTML, and thus the http://www.w3.org/TR/1999/REC-rdf-syntax- population of users was restricted to techno-savvy 19990222/ (current May 2002) . computer users. Tools like Microsoft FrontPage, [2] Berners-Lee, T., M. Fischetti, and M. Dertouzos, Netscape Composer, and countless other HTML Weaving the Web: The Original Design and generators opened up the world of the web to Ultimate Destiny of the World Wide Web by its everyday users by allowing them to create content Inventor, Harper, San Francisco, 1999. without forcing them to learn anything about HTML. [3] Hendler, Jim, “Agents and the Semantic Web,” IEEE Intelligent Systems. March/April 2001 For academics and “real world” users to start using the (Vol. 16, No. 2). semantic web, a tool for generating RDF will encourage use because it eliminates the knowledge