Last week, I participated in a WWW2007 panel called “Multimedia Metadata Standards in a Semantic Web 3.0“, where I took the opportunity to declare the Semantic Web dead. As you can imagine, such a declaration in front of a crowd of semantic web researchers provoked many responses. While I believe panels should be provocative and entertaining, I also have specific reasons for why I went as far as calling the Semantic Web “dead”. Let me explain what I mean.
There is no way that we can engage the masses in annotating media with “semantic” labels. At best, we can get the people to annotate content (such as Flickr images or YouTube videos) with short text descriptions or tags. This works only because tags are simple; powerful (can be used for many tasks) and, in some systems, carefully engineered to match the user’s natural motivations. Our best hope is to be able to take this bottoms-up annotation, or folksonomy if you will, and try to assign some semantics to it later - Flickr’s Clustering is a great example, as well as Y!RB’s TagMaps and our upcoming SIGIR paper (”Towards Automatic Extraction of Event and Place Semantics from Flickr Tags”, available in pdf).
Now, developers are people too(tm). When Web2.0 developers have any need for a multimedia standard, they will choose something that is simple, powerful, and answers their immediate needs. Semantic Web? Dublin Core? MPEG-7? I don’t think so. The masses of developers have opted to use simple formats such as (partial list) RSS, Microformats, and recently, Flickr machine tags.
Flickr machine tags are, in essence, a bottom-up way to assign “lightweight semantics” to Flickr tags/images. Machine tags are an easy way for developers to create their own semantics and applications around the Flickr platform by using a triple-tag such as “upcoming:event=144945″ to signify that a photo was taken in the event ID 144945 in the Upcoming.org event database. Machine tags are an “emerging format” that will adapt to the needs of developers and will reflect the salient properties of the data - just like tags. Flickr cannot, and probably would not want to regularize or limit the usage of machine tags. Issues will arise - for example, since the namespace for machine tags is not pre-defined (a good thing!) we may have multiple names for the same semantics. Or, developers may use the same names for semantically different subjects.
As with regular tags, it will be up to us, researchers, to make sense of the machine tags via our “tools” - be it schema mapping, pattern extraction, semantic analysis, or any other technique (content anaylsis may even help in the case of multimedia). There is simply no hope in enforcing a complete set of semantics for media (or content) annotation on the web as a whole. Which led me to declare the [grand vision of the] semantic web dead.
Well, as I mentioned above, this claim engaged the audience quite a bit (a good thing!). Some of the panel responses claimed that the machine tags are, indeed, a success, or even an instance, of the semantic web. I mentioned Aaron Cope’s statement: “machine tags are not RDF but they can play RDF on TV”. I also mentioned Dan Catt’s quadruple-hop from machine tags through RDF to JSON using Triplr and Pipes (partially in support of the connection between machine tags and the semantic web). So, it doesn’t matter whether RDF is used or not (Dave Beckett, friend of the program, and the editor of RDF as well as the man behind Triplr was in the crowd and participated in the discussion). Others pointed out that the semantic web is very successful and useful for some domains (I agree).
To summarize and conclude, let me tone down my claim. The Semantic Web is not dead; but the grand vision of “A Semantic Web” will not be achieved, despite Tim’s noble efforts. Instead, we will see the Emerging-Semantics Web, derived from how people/developers use lightweight formats and tags on popular platforms such as Flickr and YouTube. As for the panel, I concluded with quotes from Nat Torkington’s rather amusing post about the future of the web - right on the spot, but in retrospect, maybe I should have spared the injured crowd from this additional insult at that point…
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2007/5/17 15:38:00
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Yahoo研究人员宣称Semantic Web死了 （提醒：为避免误解此标题，请读完正文）
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