WebDAV-based Hypertext Annotation and Trail System Sunghun Kim, Mark Slater, E. James Whitehead, Jr. Dept. of Computer Science Baskin Engineering University of California, Santa Cruz Santa Cruz, CA 95060 USA {hunkim, mslater, ejw}@cs.ucsc.edu ABSTRACT We introduce a WebDAV-based Hypertext Annotation and Trail System (HATS). HATS provides annotation editing, deleting, searching, and sharing using server side WebDAV capabilities. It supports hyper-trail storage and examination. The paper describes the HATS architecture and WebDAV annotation schema. We compare HATS with existing web annotation systems, and discuss the advantages of using WebDAV as an annotation server. Categories and Subject Descriptors H.3.5 [Information Storage and Retrieval]: Online Information Services – Data sharing, Web-based services; H.5.4 [Information Interfaces and Presentation]: Hypertext / Hypermedia – Navigation General Terms Human Factors Keywords WebDAV, Hypertext, Hyper Trail, Annotations. 1. INTRODUCTION Most of us have had the following experience: we visit a web page, find it useful in some way, but when we try to revisit the web page later, we can’t remember where it is or how we got there. We try to find the site by looking at our bookmarks, using search engines, or closing our eyes and simply thinking about it, but finally we give up. This is too common for people who are flooded with information. Web annotation systems that have annotation storage and search functionality are useful in this situation. Many annotation systems store their data on the local machine [1]. This makes it hard to share annotations or, if you are using different computers, the annotations cannot be accessed on both machines. Other annotation systems [8, 10] use their own customized annotation server. Developing an annotation server with proprietary authentication and storage systems is expensive. Even when the interface to the server is public, the small installed base of a single system does not encourage external development of clients. Also, annotation systems rarely track the hyper-trails to an annotated web page. To address these problems, we developed the WebDAV-based Hypertext Annotation and Trail System (HATS). It has annotation storage, search, and viewing functionality, supported on the server side by WebDAV. HATS also supports hyper-trail storage and viewing. To ensure convenience for the user, we implemented the first HATS client as a Mozilla plug-in. Using HATS, users can add an annotation to a web page as easily as they add a new bookmark. HATS’ most important contribution is the use of WebDAV, a standard protocol. This reduces the cost of system development and increases interoperability – a WebDAV-enabled client can access annotation information. In addition, since WebDAV is an XML-based protocol, we will have developed a reusable XML schema to describe our annotation system. The addition of hyper- trail information allows us to perform data mining operations that would be impossible otherwise. 2. WEBDAV WebDAV is a suite of protocol extensions to HTTP/1.1 that supports collaborative authoring and namespace management of resources, setting and retrieving of metadata properties, access control, and resource versioning on remote web servers [2]. The suite includes the DeltaV (versioning) [3], DASL (searching) [4], and the WebDAV core (authoring) [2] protocols. The WebDAV core protocol [3] enables users to create, modify, and delete resources or collections on a WebDAV server. It also provides metadata management using PROPFIND and PROPPATCH messages. DASL provides property and content search capability. HATS represents each annotated URL as a resource; annotations are stored as properties of this resource. Figure 1. The HATS Sidebar. Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, or republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee. HT’04, August 9-13, 2004, Santa Cruz, California, USA. Copyright 2000 ACM 1-58113-000-0/00/0000…$5.00.