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What’s become of transcoding?

Feb 26, 20032 mins
Cisco SystemsMobileNetwork Security

* Adapting Web content to small devices

Last time, I mentioned that adapting small-screen mobile devices to back-end core business applications remains important, if you believe that users of Palm, PocketPC, RIM and other small form-factor devices will be accessing your public Web pages or your Web-based intranet applications.

One component of enabling smaller devices to access resources originally created for full-size screens involves transcoding. We’ve discussed this capability in this newsletter, but it’s been a long time. Transcoding basically involves cleaning up and transforming Web-based content into the markup language and display format appropriate to the mobile device issuing the request for it. This might involve some “screen scraping”-pulling only the pertinent components off the back-end page for display.

As an example of how this works, let’s take a brief look at Cisco’s flagship transcoding device, called the Content Transformation Engine (CTE) 1400. This box is a stand-alone appliance that “mobilizes” back-end data and applications that have been stored in a Web format like HTML and XML.

The appliance serves as a proxy when a content request comes in. It transcodes back-end content in accordance with content filtering rules that are set by the content owner using a Cisco management application called CTE Design Studio.

An Extensible Style Language Transformation (XSLT) engine inside the Cisco appliance handles the markup-language reformatting. (XSLT is a World Wide Web Consortium-standard language used in XSL style sheets to transform XML documents into other XML documents.)

Another Cisco CTE 1400 process is Tidy++, an enhanced version of the W3C’s Tidy protocol. Tidy++ reportedly identifies unique ways that Web designers have made mistakes in HTML coding and fixes them before transformation.

In addition to front-ending enterprise content servers, the transcoding engine could be installed in front of the servers in a content delivery network; in the data center of a service provider that offers content-hosting services. Also, at some point, mobile network operators themselves may wish to get into the content hosting business. In such cases, the transcoding equipment would sit in the mobile network operator point of presence.