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Web Annotations

While web annotations are not a new research topic and a few companies wanting to capitalize on this space have already come and gone, enough has changed in the web infrastructure to reconsider this area. Better browsers, new standards, and a set of prototype systems make this a perfect time to consider a second generation of annotation systems.

The Concept

Annotations are a broadly useful mechanism that can support a number of document and database management applications:
  • provide a trace of use
  • third party commentary
  • information sharing
  • information filtering
  • semantic labeling of document content
  • enhanced search

But it continues to be hard to publish to the web. If better tools are provided to information consumers then readers will be able to add commentary, make new connections, interpret content, and otherwise promote an accretion of both structure and content on the web. This process will add new semantics to the web and this new information will be the source for new approaches to searching and filtering of information.

The progression from the collection of annotations of free-text as stupid assertions to 1st order propositional assertions with more semantic binding will evolve the web from where it is today to the vision of a semantic web. Key to this transition is the deployment of annotation servers to particular market segments that have strong demand for more structured queries of web based information.

These market segments are likely to be in knowledge intensive industries such as the consulting, legal, and financial markets.

Past Research and Implementations

As far back as the inception of Memex [Bush45] researchers have postulated the many features and benefits of capturing and incorporating note taking in an automated fashion.

Much human factors research has gone into understanding our current use of annotations [Marsh97], and evaluating the useful features of an annotation system [Ovsi01].

Annotations have even been implemented for the web in Mosaic 1.2 ( and here ), or Mosaic 2.6 beta 1 [Brav], CritLlink [Yee98] and ThirdVoice.

However, the problems with mass adoption have been in browser support for editing a page, overlaying information, and sourcing of markup from multiple servers on the same page. Further, lack of support for bi-directional links and links to parts of a resource to help support links outside of the referenced resources complicated the architectures of early annotation services, forcing a slew of proxy server based approaches with the inherent weaknesses of this design [Vasu99].

But now we have IE5.5, with more than 85% penetration, with some support for XPointer (in MSXML), an RDF based implementation for annotation servers from the Annotea project in the new clients for Annotea.

Companies

There are a pile of companies in and around this space, some of these are squarely in the annotation space (e-quill), others are considered browser accesories, messaging companies (ThirdVoice, Odigo), and context services (Alexa).

The key ones in my mind are:

Other players include:

A bunch have already fallen off the map:

And a number of interesting domains are taken, but not up and running yet:

Reviewing the companies in the best position:

EQuill develops Web-based solutions that enable businesses to communicate and collaborate more effectively with their visual markup tool. You could say they offer a hosted workflow management suite. It's an excellent tool, but the resulting captured documents on their Markup Server don't seem well suited for complex search.

uTOK , the Users' Tree of Knowledge, developed a Web browsing companion that allows users to share knowledge through virtual notes.

Also, Noteclip has a key piece of client technology that seems useful.

Sentius's RichLink IDC paper

The Architecture

Since the release of editing, DHTML, and DOM2 support within IE5.5 and the recent release of the W3C Annotea server in conjunction with all the supporting standards (XPath, RDF, WebDAV, and UDDI), it should now be easier to build and deploy standards based annotation servers within enterprises.

However, we are still early in this space. Companies will have to find their market and differentiate themselves. Technically they will have to solve design problems to meet performance and scalability.

There will be a number of architectual choices that will be determined by the domain that they are applied to. For example:

  1. What context do you capture at annotation creation?
  2. How much do you capture (document and annotation)?
  3. How do you combine annotations?
  4. What kind of search queries do you need to support?
  5. How do you manage authentication and access control permissions?
  6. etc.

An interesting technology to scale annotiation servers is Guha's RDFdb IFF the server is based on RDF. In certain domains however, users will be able to use much more structured ontologies implemented on regular DBMS servers with an XML Schema.

The deployment of annotation servers for the public web still need to solve issues of discovery, scale, and trust.

July 2001 update.

Microsoft's announcement of SmartTags, had the rest of the world up in arms, forcing MS to back off and cacel its release when it must have noticed these meta tags showing up everywhere:

 <meta name="MSSmartTagsPreventParsing" content="TRUE">

Microsoft has been aware of the Annotation space since 1997, and has an Annotation Server team in MS Office, but the lack of marketing subtlety of this 800 lbs. gorilla continues to engender a lack of trust.

This leaves the window open on the client, server, and service space. Check TopText.

Turns out that web logs, or blogs, are really the ones annotating everything out there, and now Blogdex is starting to keep track of the top links. Speedle does the same, but is centered around email. None of them really enable the annotation user interface envisioned, and maybe that is irrelevant. More later ...

People

References

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© 2000-2007 Paul Perry