L C SL C S Haystack Dennis Quan Oxygen Workshop, January, 2002

L C SL C S Introduction Personalized information store Semistructured data with arbitrary metadata Unified ontology Standards-based components and infrastructure Compatible with existing systems Example user interface Integration with mail and groupware concepts Collaboration possibilities

L C SL C S What is an Ontology? “The branch of metaphysics that deals with the nature of being. “ – American Heritage Dictionary Describes relationships between different objects in a system Like schemata or class hierarchies

L C SL C S Resource Description Format (RDF) Standard defined by W3C in 1999 ( Models statements of the form: Can be expressed as a labeled, directed graph For example, statements “Bob likes Alice” and “Bob likes Jane”: Bob Alice likes Jane likes

L C SL C S RDF Store RDF Store used by Haystack to store all information Runs off of a standard SQL database Provides querying facility Example: who likes Jane? (?x likes Jane); return ?x

L C SL C S Belief With multitude of information, how much is believable? Annotate who said what Also can describe belief network using RDF Example: John says that Bob likes Jane, and Bob believes John Belief Server—component of Haystack that evaluates belief network and “filters” the store for information believed by the user Bo b Jan e like s assertedBy John believes

L C SL C S Collections Basic means of aggregation Difference from “folders”: containment versus membership Categorization and subcategories

L C SL C S Queries One possible means for constructing a collection (result set) Can use all possible metadata fields to construct query Natural language Multiple query sources—the Web, other people’s Haystacks, etc. Automatic update of query result sets Possibilities for machine learning (e.g., when a user removes an item from a result set—a message to Haystack that an object does not belong)

L C SL C S Services Callable services in Haystack Also, automatic agents that respond to events Available methods described in metadata Haystack service initialization script also described in metadata Services mainly written in Java, but can be written in any language

L C SL C S SOAP, WSDL and UDDI Relationship to Web Services standards: –Simple Object Access Protocol (SOAP) –Web Services Description Language (WSDL) us/dnwebsrv/html/wsdl.asp –Universal Description, Discovery and Integration (UDDI) SOAP and HTTP/PUT used as protocols for communication between services, including the RDF Store RDFized version of WSDL used to describe services’ interfaces UDDI query functionality easily modeled in RDF query

L C SL C S Inference Layer The semantics defined in RDF often permit deduction Example: Fido is a dog and dogs are mammals  Fido is a mammal Deduced knowledge is useful and should be stored Inference Layer recognizes patterns and triggers agents/services to perform deduction

L C SL C S Views May be several different ways of looking at an object Example: appointment book can be viewed as a sortable list of appointments or a calendar Views are a distinct type of object used to model these different ways of looking at objects

L C SL C S User Interface Ontology UI components (e.g. JavaBeans, ActiveX controls) rich sources of metadata Form descriptions also describable with metadata Possible to construct a directed graph that models a user interface Similar in concept to XUL Permits dynamic deduction of user interface similar to XSLT, except semantic rather than syntactic Part: a Haystack UI component ViewPart: a kind of part specially designed to display a specific kind of View

L C SL C S SWT Cross-platform Java widget toolkit Part of Eclipse project ( Uses native operating systems’ widgets, avoiding performance problems Used for Part framework Integrates with Mozilla web browser Also possible to use ActiveX controls and GTK widgets

L C SL C S Ozone Haystack experimental user interface Modeled after a web browser Uses parts to describe user interface

L C SL C S Browse/Query Paradigm Browsing: going through nested folders/categories to locate sought item(s) Query: giving an explicit set of conditions to locate sought item(s) Ozone adopts hybrid Browse/Query paradigm Traditional subcategories still present in Collection view Also, parameterized categories similar to queries Previously issued queries persist as subcategories

L C SL C S Mail a good source of metadata-rich documents Messages, addresses, people and groups can be modeled in RDF Haystack agents can be used to filter to make it more manageable Many management techniques applicable to documents in general and vice versa

L C SL C S Storage Model Objects in Haystack named by Uniform Resource Identifiers (URIs) URLs are a subclass of URIs Documents and web pages can be named by URLs HTTP/FTP/WebDAV servers can then be used to store documents Inefficient to store terabytes of “data” in RDF when existing storage solutions are effective

L C SL C S Collaboration Allow Haystack-Haystack and Haystack-Semantic Web information exchange Filtration of imported data Who’s the expert? problem Privacy concerns Different ways of organizing information between different parties Can be used to model mailing lists, newsgroups, and groupware

L C SL C S Ontological Conversion Unlikely that everyone will agree on the same schemata Ontological conversion converts from one schema to another Can be implemented as Haystack agents that respond to metadata with “foreign” schemata

L C SL C S Implementation Written for Java 2 platform (JDK 1.3.1) SWT (Eclipse) used for user interface components Mozilla web browser HSQL open source SQL database written in Java Lucene (Apache Jakarta project) search engine written in Java Tomcat (Apache Jakarta project) web server written in Java Parts written in Jython, Java-based Python interpreter