Web Tagging with Annotea Shared/Social
Bookmarks and Topics

Marja-Riitta Koivunen, Ph.D.




Annotea originated metadata based, shared/social bookmarks and topics as a logical extension to Annotea shared annotations and replies. These bookmarks and topics precede the tagging and social bookmarking services and tools existing today. Annotea bookmarks and topics support ordinary users in Web tagging and recalling relevant information while supporting the use of their own personal concepts (folksonomies). The user concepts can be shared and linked to more standard concepts when users learn about them. Like other Annotea objects, bookmarks and topics help collaboration in the context of the Web documents, but also support other user interfaces. The Semantic Web technologies support merging Annotea objects from different sources and easily extending the bookmark and topic information.

Categories and Subject Descriptors

H.5.3 [Group and Organization Interfaces]: Computer-supported Cooperative Work, Web-based Interaction; I.2.4 [Knowledge Representation Formalisms and Methods]: Semantic Networks –Semantic Web

General Terms

Design, Human Factors.


Social bookmarks, Topics, Semantic Web, Ontologies, Tagging, Folksonomies


Humans are meaning makers. They create concepts, make associations, comment, clarify, annotate, review, organize, bookmark, tag and file into categories often starting from personal concepts that are shared by different groups when they become more developed. Annotea [16] lets ordinary users create and collaboratively share familiar objects adding meaning to Web, including annotations, discussions threads, bookmarks, and topics. Annotea objects can be explored in the context of the Web resources they refer to but they can also be used in many other innovative ways.  Annotea bookmarks with topics [10, 11, 14, 15] can be used for simple Web tagging and precede Web tagging services, such as [8] but they can also offer other information and support for various user needs.

Annotea gets its inspiration from observing users’ needs and problems and explores user scenarios based on those observations [10]. It uses the Semantic Web technologies for implementation the solutions but hides the Semantic Web under familiar objects and user interfaces. Annotea defines a basic annotation/bookmarking framework [9] with schemas for Annotea objects [2, 4, 12] and server protocols [17]. In addition, sample user interfaces illustrate how to utilize the framework, for instance, in Amaya browser/editor [1] and in Annotea Ubimarks [5]. In addition, many other clients have been developed outside the Annotea team. Semantic Web technologies [7] support seamless merging of Annotea objects from different sources and easy extensions of these objects.

Annotea shared or social bookmarks allow users to recall Web resources, such as Web documents, services, music, images and blogs while storing additional information about these resources. Annotea topics support user defined simple concepts (tags). These can be used to form personal ontologies (folksonomies). In Annotea the topics can be stored locally or shared with user groups. The bookmarks and topics can be linked to standard concepts gradually when the user has learned enough to make that connection instead of forcing the users to learn standard ontologies before they can start developing their ideas.

Commonly available shared bookmarks repositories can create a network effect leading to many new discoveries. Annotea bookmarks and topics help collaboration and finding relevant information even when users use different concepts, which is often the case in cross disciplinary fields, such as life science or usability/user experience or even in marketing or research where users are awarded from finding original concepts instead of using the already existing ones.

In addition to proving a simple tool for creating meaning, Annotea bookmarks and topics can be used as user profiles, collected to repositories and used with search engines and data mining applications. Annotea bookmarks and topics can also contain information not just about the user but his or her social network. Again, this can be used to support the finding of more relevant information.

As shared bookmarks are easy to create we hope to be able to see network effects in many applications using bookmark repositories, such as data mining applications, services with user profiles, search engines and applications organizing blog type information.


Annotea [9, 16] has demonstrated the use of the Semantic Web based annotations and replies that can be stored to different annotation servers. Annotea shared bookmarks and topics are based on the same technology.

Figure 1 presents the basic Annotea architecture. Various RDF metadata stores and services can store Annotea objects, such as the bookmarks and topics we are mostly interested in the context of tagging. These objects have URIs and properties.

annotea architecture

Figure 1. The basic Annotea architecture.

Annotea protocol has been defined for the metadata stores based on HTTP. With bookmarks and topics we also use normal HTTP, FTP, and possibly other Web protocols to store them as Web documents.

 Annotea user interfaces provide different views to the Annotea objects. When these interfaces are attached to browsers users can seamlessly collaborate via Annotea objects in the context of the Web documents or other Web resources. In addition, Annotea objects can be used in many other kinds of applications and user interfaces. For instance, they can form user defined profiles for services or information repositories for selected domains that can help order results from search agent in a more meaningful way [18].


presenting bookmarks and topics as a hierarchy

Figure 2. Bookmark and topic hierarchy.

During the first phase of Annotea development many informal discussions were performed with users and additional user scenarios were developed. The need for categories was high on the users’ wish list, especially status categories were needed to mark the processed annotations. During the second phase, we selected to focus our scarce resources to broaden the scope and add bookmark and topic objects. The goal was to make sure that our approach was extensible and the different metaphors could work together. In addition, this approach gave us a chance to experiment with some other ideas before going back and improving the annotation implementations.

The shared bookmark metaphor with topics was perfect for Annotea as shared bookmarks could easily be seen as a variation of annotations. Furthermore, most users were not only familiar with bookmarks but had actually used traditional bookmark implementations. In addition, traditional browser bookmark user interfaces have a lot of enhancement possibilities that can benefit from the Semantic Web approach. For instance, the user interface can utilize the document context to remind the user that she has previously bookmarked the page or let the user define, share and link to other users' topics or categories. Furthermore, many other applications can utilize the bookmark metadata if it becomes widely available.

Annotea topics allow users to create and maintain shared classifications or informal categories [13]. A bookmark can be cataloged under one or more topics and presented to the user in a topic hierarchy (see Figure 2).

Annotea bookmark and topic user interfaces also provide information in document context. When a user browses pages she can see that someone has bookmarked a page from the pagemark icon that opens up to show a list of bookmarks. These bookmarks and their topics can be easily followed to find information about related documents in the RDF stores the user is currently subscribing.

Users collaborating in similar or related research areas can benefit from the bookmark and topic information. They can see bookmarks on a current page and find related topics and other bookmarks to possibly interesting documents under these topics. For instance, in Figure 3 the user sees that the page about Groucho Marx has been bookmarked by looking the “Pagemarks” icon on the left side of the toolbar, opens the Bookmarks on page window sees two topics “Actors” and “Writers”, and presses the bookmarks link related to “Writers” to find other “Writers”.

opening bookmarks on a page and clicking to bookmarks on related topics

Figure 3. Following the link chain from bookmarks on this page to related topics and bookmarks.

As the Annotea topics are user generated they can support learning. During the early phases of innovations and research the topics can be as vague as needed. When more learning happens and standard concepts are discovered and understood the user can refine his or her own topics and link them to concepts in well established ontologies.

using topics to add status

Figure 4. Using topics for attaching status values for bookmarked XUL problems.

The Annotea topics can easily define concepts outside the conventional categories, such as status (see Figure 4). If the topics are separated from the bookmark stores the user can define which aspects she is interested in at each moment by subscribing those topic hierarchies. Similarly, the presented bookmark stores can be selected in a certain domain area or by the research group depending on how they are organized. There are many possibilities for enhancing this user interface.

<?xml version="1.0"?>

<RDF:RDF xmlns:foaf="http://xmlns.com/foaf/0.1/"

  <bm:Topic RDF:about="urn:uid:025f3d84-57bd-11da-924d-b619a79a047d"
                   a:created="Thu, 17 Nov 2005 22:53:14 GMT"
                   dc:description="Annotea Clients"
                   dc:date="Thu, 17 Nov 2005 22:55:11 GMT">
    <foaf:maker RDF:resource="http://www.annotea.org/marja#marja"/>
    <bm:subTopicOf RDF:resource="urn:uid:22f7e3fc-57bd-11da-aa9c-82da544b130f"/>

  <bm:Bookmark RDF:about="urn:uid:a3b4fd62-57be-11da-8d83-f5f81b4e7204"
                   dc:title="Annotea shared bookmarks development"
                   dc:date="Thu, 17 Nov 2005 23:05:26 GMT"
                   a:created="Thu, 17 Nov 2005 23:05:26 GMT">
    <foaf:maker RDF:resource="http://www.annotea.org/marja#marja"/>
    <bm:recalls RDF:resource="http://www.annotea.org/mozilla/ubi.html"/>
    <bm:hasTopic RDF:resource="urn:uid:025f3d84-57bd-11da-924d-b619a79a047d"/>


Figure 5. A sample Annotea Topic and Bookmark with foaf:maker information.


Annotea usually stores some basic information about the bookmarks. For instance who has created it and when it was created. Other information can also be added. For instance, it is easy to use different descriptions of the user. For instance, in Annotea Ubimarks we let the user to add a URI to his or her social network information by using foaf:maker when the user feels comfortable in using it (see Figure 5). This social network information can be used as additional help when trying to find related documents in some domain area. Similarly, other properties can be easily added to the bookmark and topic objects as well.


mixing bookmarks and annotations to mark a real book

Figure 6. Bookmarks and annotation concepts mix in the real world.

The Annotea objects, especially annotations and bookmarks, do not differ very much from each other and can be easily thought as variations of the same class. However, we have also had long and intense discussions with users seeing annotations and bookmarks as a totally different concept and explaining that it would be confusing if bookmarks were annotations. On the other hand, we also have users who want to immediately extend the bookmarks so that they can refer not only to a Web resource with a URI but also to a part of a document in a similar way as annotations.

The Semantic Web metadata of the objects is easy to extend in different ways but designing the user interface to be both simple and expressive enough is critical. Our current view is to keep things simple and see what happens when users start using these interfaces more. Our hope is to be able to experiment in Mozilla with Annozilla [6], an Annotea client for annotations and Ubimarks, an Annotea client for bookmarks and topics.

One solution would be to let users create annotations to point to parts of the document and then bookmark that annotation to give it a category and make it easy to find. This would match nicely the way the annotations and bookmarks are combined in Figure 6 examining the real world usage of annotations and bookmarks.


Annotea objects for shared/social bookmarks and topics provide ordinary users familiar metaphors for Web tagging and creating folksonomies. Furthermore, they let the users generate reusable and easily extendible Semantic Web metadata without having to learn and understand more about the Semantic Web.

Unlike many currently popular services Annotea framework let’s users have a choice where to store the bookmarks and topics. Users subscribe the data stores containing the various Annotea objects they are interested in at that moment. Stores can be local files, global servers and or Web documents containing the metadata. Web documents offer users an easy alternative to get started without investing in installation of a server. They can also be used to archive snapshots of the selected Annotea objects outside the server.

Furthermore Annotea object metadata generated by the users can be easily combined and reused in many other applications, such as user profiles for services, data mining and search engine applications, chatrooms, and blogs.

For developers Annotea offers an easy and flexible interface for merging metadata from several different sources and doing queries against it. Different views to the data can be created easily, and it is easy to let the users follow tracks of data from the information on the current page to possibly related information. Extending the Semantic Web data in Annotea objects is easy as well. Defining a simple user interface for extensions is relatively easy, but adding more complex user interface definitions to the extensions needs more research.


Many people have contributed to Annotea and helped to make it what it is today. I want to give special thanks to Jose Kahan, Eric Prud'hommeaux and Ralph Swick.


[1] Amaya homepage, http://www.w3.org/Amaya

[2] Annotea annotation schema, http://www.w3.org/2000/10/annotation-ns

[3] Annotea homepage at W3C, http://www.w3.org/2001/Annotea

[4] Annotea thread schema, http://www.w3.org/2001/03/thread

[5] Annotea Ubimarks homepage, http://www.annotea.org/mozilla/ubi.html

[6] Annozilla home page, http://annozilla.mozdev.org/

[7] Brickley, D., and Guha R.V. (eds.). RDF Vocabulary Description Language 1.0: RDF Schema, W3C Recommendation 10 February 2004. http://www.w3.org/TR/2004/REC-rdf­schema-20040210/

[8] Del.icio.us homepage, http://del.icio.us/

[9] Kahan, J., Koivunen, M., Prud'Hommeaux, E., and Swick, R. Annotea: An Open RDF Infrastructure for Shared Web Annotations, in Proc. of the WWW10 International Conference, Hong Kong, May 2001 http://www10.org/cdrom/papers/488/index.html.

[10] Koivunen, M. and Swick, R. Metadata Based Annotation Infrastructure offers Flexibility and Extensibility for Collaborative Applications and Beyond, In Proc. of the KCAP 2001 Conference, http://www.w3.org/2001/Annotea/Papers/KCAP01/annotea.html

[11] Koivunen, M., Swick, R., Kahan, J., Prud'Hommeaux, E.,
Topics in Annotea: Extending the Basic Architecture

WWW2002 Developers Day, Honolulu, May 2002

[12] Koivunen, M., Swick, R., Kahan, J., Prud'hommeaux, E., An Annotea Bookmark Schema, 2003, http://www.w3.org/2003/07/Annotea/BookmarkSchema-20030707

[13] Koivunen, M. Scenario: Organizing CML cancer research knowledge by using Annotea shared bookmarks, 2003, http://www.w3.org/2003/12/cmlcase/cml.html

[14] Koivunen, M., Swick, R., and Prud'hommeaux, E. Annotea Shared Bookmarks, 2003, In Proc. of KCAP 2003, http://www.w3.org/2001/Annotea/Papers/KCAP03/annoteabm.html

[15] Koivunen, M., Annotea shared bookmarks: Semantic Web at your fingertips, In Proc. Of the ISWC 2004 Conference Demonstrations Session. http://www.annotea.org/ISWC2004/annoteademo.html

[16] Koivunen, M. Annotea and Semantic Web Supported Collaboration, in Proc. Of the ESWC2005 Conference, Crete, May 2005. http://kmi.open.ac.uk/events/usersweb/papers/01_koivunen_final.pdf

[17] Swick, R.,  Prud’Hommeaux, E.,  Koivunen, M., Kahan, J., Annotea protocols,

[18] Shiraishi, N. (2004) The RDF Trust Model Using RDF Bookmark and it's Application. In Proc. of WWW2004 Workshop on Content Labeling -Technical and Socio-Cultural Challenges and Solutions. http://web.sfc.keio.ac.jp/~kaz/www2004/papers/ns.pdf