Web annotation

=Ka-Ping Yee, CritLink: Advanced Hyperlinks Enable Public Annotation on the Web (2002)= K.-P. Yee. CritLink: Better Hyperlinks for the WWW. Submitted to Hypertext '98, Apr. 1998. http://crit.org/http://crit.org/~ping/ht98.html. Abstract This paper describes a set of hypertext linking features that are essential for supporting critical discussion and document annotation, but are missing from the Web. An implementation of these features called "CritLink" enables users to attach annotations to any location on any public page, and to view the annotations on any page, without having to install any special client or server software. All browsers (including text-only browsers) and all operating systems are supported. Annotations can have types, can be public or private, and can annotate other annotations.


 * Users access the CritLink server first. Then browse the WWW through the CritLink server. Annotations are stored in CritLink server.
 * Annotations are stored as meta-data to the annotated web page.

=Annotea Project by Marja-Riitta Koivunen, Ph.D.= Computer Networks Volume 39, Issue 5, 5 August 2002, Pages 589–608 Annotea: an open RDF infrastructure for shared Web annotations J. Kahana,, , M.-R. Koivunenb, 1,, E. Prud'Hommeauxb, , R.R. Swickb, http://www.annotea.org/eswc2005/01_koivunen_final.pdf
 * Annotations with address is saved in Annotea server. Readers load both source from source server and annotation from Annotea server.
 * --quotes--Annotea is a W3C LEAD (Live Early Adoption and Demonstration) project under Semantic Web Advanced Development (SWAD). Annotea enhances collaboration via shared metadata based Web annotations, bookmarks, and their combinations. By annotations we mean comments, notes, explanations, or other types of external remarks that can be attached to any Web document or a selected part of the document without actually needing to touch the document. When the user gets the document he or she can also load the annotations attached to it from a selected annotation server or several servers and see what his peer group thinks. Similarly shared bookmarks can be attached to Web documents to help organize them under different topics, to easily find them later, to help find related material and to collaboratively filter bookmarked material.

http://www.w3.org/2001/Annotea/Papers/www10/annotea-www10.html


 * --quotes--"This section discusses some previous annotation approaches. We concentrate on document-centered approaches where users are browsing documents and examining annotations related to them. There are also discussion-centered approaches to annotations, such as HyperNews [12], where users browse discussion messages and threads and follow a link to a document that these messages annotate. Web annotations first appeared in version 1.2 of Mosaic [18, 19], almost ten years ago, and many other web annotation aware tools or servers have seen the light since then, such as CritLink [25] and ThirdVoice [23]. [10, 11] list other existing annotation technologies. Due to the lack of existing annotation standards, most of these proposals are proprietary or closed.
 * --The two main categories to Web annotation systems are proxy-based approaches and browser-based approaches. In a proxy-based approach, annotations are stored and merged with a Web document by a proxy server. The browser user agent only sees the result of the merge, typically with some semantic content removed.
 * -- In a browser-based approach the browser is enhanced (either by an external application or by a plugin) to merge the document and the annotation data just prior to presenting the content to the user. The annotation data is stored in the proxy or a separate annotation server. It is also possible to store annotations locally or provide site specific annotations, but these are less interesting to us because of their limitations.


 * -- The CritLink [25] annotation tool uses the proxy approach where a Web page and its annotations are served through a different URI address than the original page. This approach works with any existing browser. However, the user must use different addresses for the document depending on which annotation proxy server is used. This is a limitation when a user wants to use more than one annotation server.
 * --The proxy approach also inherently restricts the types of content that can be annotated and the presentation styles that can be used for the annotations. Typically, presentation of the annotations is limited to the presentation styles available through HTML. Finally, as the browser does not have any knowledge about annotations, it makes it harder to filter the annotations locally, without having to send a new request to the proxy server.
 * --ThirdVoice [23] uses plugins to enhance web browsers so that they understand annotations. The users can annotate the page or some text on the page with discussions on selected topics. The discussions can be closed to a group of participants or open to anybody. Unfortunately, users cannot host their own servers.


 * --IMarkup [13] is an Internet Explorer annotation tool that has an interesting user interface. Users have a wide variety of palettes for annotation markers and can even circle parts of the text with something akin to a real marker. Annotations can be placed anywhere on the browser's document window, without taking into account the markup of the document itself. All the annotations are local. A menu entry allows to mail annotations to other users and to import them. The format used for describing annotations is proprietary and too related to the browser's API, making their use with other tools practically impossible. An interesting possibility for presenting the annotations on a Web page is to use internal DOM [14] events without actually changing the mark-up of the page. Yawas [6] is an annotation tool that uses this approach. It codes the annotations into an extended URI format and uses local files similar to bookmark files to store and retrieve the annotations. A modified browser can transform the URI format into DOM events. The local annotation files can be sent to other users only by mail or copied by other means. There is no provision for having active links or filtering options. This kind of approach is limited by the API provided by the browser. XLink [8], an XML linking technology currently under development in W3C, has some built in features in the mark-up for creating annotations. For instance, it is possible to store XLink arcs in an external document that can be loaded with another document. The content defined by the end locator of an XLink arc may be embedded to the location in a document defined by a starting locator of the arc. Using XLink provides the means to easily present the annotations in predefined ways in any browser implementing XLink. However, the metadata properties that can be expressed with XLink are limited. "

=Pan-Browser Support for Annotations and Other Meta-Information on the World Wide Web (1996)Matthew A. Schickler, Murray S. Mazer, and Charles Brooks = http://www.ra.ethz.ch/CDstore/www5/www418/overview.htm Matthew A. Schickler, Murray S. Mazer, and Charles Brooks OSF Research Institute 11 Cambridge Center Cambridge, MA 02142 USA
 * --quote--This paper describes an innovative approach to enabling group members independently to create and share commentary about the content of documents accessible via the Web. In particular, the system described supports the creation, presentation, viewing, and control of user-created meta-information, which is displayed with the corresponding documents but stored separately from them.

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 * Cloud based service for web annotation. The sources are stored in Diigo server where users modifications can be super-imposed.
 * Cannot applied to copyrighted material.