In this 5th post on the Semantic Web and our Web 2.0 inspired implementation, we are going to get to the heart of the <alt> meta data implementation.

In previous posts, we've looked at our divergence from the traditional Semantic Web and why it's necessary to do so: we have seen that user generated meta data is the only viable approach to implement the Semantic Web as publisher generated meta data is a model for control and is ripe for abuse. We've also demonstrated that user ownership of meta data is a requirement to make the Semantic Web a reality as only a user knows what he wants. And in the last entry, we showed that document-level meta data is irrelevant and users only care about the data contained within the document.

The <alt> meta data implementation has the following 7 characteristics:

1. 1.Dynamic Meta Data. In the traditional Semantic Web, meta data is static as it is contained within the web page. As our meta data implementation is under user control, it may be easily modified as needed by the user or extended by a service provider.
   
   

2. 2.Versional Meta Data. Classically, meta data in the Semantic Web is not time stamped or versioned. In the Web 2.0 Mashup world, users need to know when was the last time a piece of web data was changed. As our meta data implementation is element-centric; versioning allows the users to see data changes over time enabling change detection and notification.
   
   

3. 3.Extensible Meta Data. In the most recent meta data standards such as RDFa, meta data is implemented in custom XHTML attributes. As it is hard-coded by the publisher, it is impossible to augment.
   
   In our meta data implementation, for example, we encode an American English text-to-speech version of the HTML element thereby empowering the vision impaired. Users may extend the meta data with alternative languages and empower non-American English web users.
   
   

4. 4.Verifiable Meta Data. Publisher defined meta data whether in the form of embedded RDF, RDFa, or even Microformats may not be authoritative due to stale data-- usually due to page mirroring-- or forged sites. In our implementation, meta data can be compared by time stamp and other criterion to determine correctness.
   
   

5. 5.Executable Meta Data. In the traditional Semantic Web, most/all meta data implementations exist to provide data to RDF databases for analysis using languages such as SPARQL. In our implementation, the meta data may be used for query, verification, resource resolution, update, and application processing.
   
   Speech synthesis is an example of direct meta data evaluation.
   
   

6. 6.Data Encapsulation in Meta Data. In the traditional Semantic Web, meta data does not contain the data it describes (or "repeats the data" as is described in RDFa standard.) Rather, it annotates the data.
   
   As meta data is stored externally to the HTML page in our implementation: we store a copy of the original data, a text-to-speech version of the original data, and subsequent versions of the data. This approach allows multiple applications to process the meta data without fear of ad-hoc use conflicting with ontology standardization which usually requires several iterations to get right.
   
   So, the <alt> meta data implementation supports both the needs of the many (users) as well as the needs of the few (ontologists)... the best of both worlds.
   
   

7. 7.P2P Meta Data Sharing. In the traditional Semantic Web, meta data is imported into an RDF database. A SPARQL query is then executed to obtain "knowledge".
   
   This architecture only benefits service providers and precludes web users from getting the "knowledge". Just how many users are going to write SPARQL or install an RDF database? On the other hand, probably several "knowledge" service providers will provide a watered-down web interface in effect building walled gardens to control the user. Do you think that a service provider will allow user queries to be executed directly on "their" databases?
   
   Our Web 2.0 tools and server support personal meta data registries where meta data can be browsed and shared. Today meta data is shared with other users manually, but we plan to support remote meta data sharing via peer-to-peer technologies.
   
   A user can derive "knowledge" from 1 meta data source-- as we saw in the Wi-Fi coffee list example-- or through the composition of multiple meta data definitions. And as you should know, a data composition is also called a Mashup.
   
   

So, now you've read about the 7 most important characteristics of our meta data implementation. And you also know why each one is a fundamental divergence from the traditional Semantic Web... saving the vision by updating the implementation.