Sunday, February 22, 2009

Adapting Content

Franklin Reynolds, "Adapting Content", IEEE Pervasive Computing, vol. 7, no. 4, pp. 6-8, Oct.-Dec. 2008

This is an interesting article which provides a solid description on how ‘device independence’ can be achieved by utilizing recent W3C standards. It provides a good introduction, highlights some of the main issues, and gives accurate pointers to the state-of-the-art W3C standards and those under development. There’s one statement in the article that I find very interesting which is:
“DIAL will make it possible to create a Web page whose presentation can be controlled by the properties of a delivery context.”
DIAL (Device Independent Authoring Language) and the delivery context – cf. Delivery Context Client Interfaces (DCCI) and Delivery Context Ontology (DCO) – seem to be a competitor of MPEG’s Digital Item Declaration (DID), Multimedia Description Schemes (MDS), and Usage Environment Description (UED). I wonder whether there exists a thorough and, of course, not taking sides comparison of these formats and whether it is possible to harmonize at least parts thereof. For sure that’s a job for academics because these standardization bodies might not be interested in doing this let’s call it academic exercise.

Furthermore, still a big issue is how all these assets are actually communicated over the various networks. The article mentions IETF’s “Transparent Content Negotiation in HTTP” although this RFC2295 is rather old and, more importantly, is ‘experimental’. Additionally, there exist some extensions of HTTP to carry CC/PP-based descriptions defined in RFC2774 identifying the profile or a difference to an existing profile - also ‘experimental’. However, DCO (an all others) may require yet another HTTP extension and, thus, there’s a need to decouple the communication/negotiation of the delivery context and usage environment properties from the actual (transport) protocol.

Finally, CC/PP defines only a ‘container format’, i.e., the language constructs, while UAProf defines the actual ‘terms’, i.e., a vocabulary of actual hardware, software, … characteristics for mobile devices.

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