 - Transcoding is a technology used to adapt computer application displays and Web content so that they can be viewed on any of the increasing number of diverse devices on the market. Transcoding servers and services reformat material that would otherwise have to be developed separately for display on different platforms. Working like an interpreter, the technology translates content to suitable formats for various platforms, regardless of protocol, application, screen size, and language used. A variant of transcoding has been used for some time in Web applications such as AltaVista's Babel Fish language translation program.
Although wireless connectivity is steadily increasing, the question of how to enable content display has been problematic. Handheld wireless devices - such as the smartphone and the personal digital assistant (PDA) - tend to have limitations in terms of power, memory, resolution, and screen size; this means that they have problems displaying Web content suitable for a full-sized computer. Typically, the mobile user wants to be able to access the crucial data (such as a stock quote, for example) without any extra detail or graphic display. Without transcoding, content must be written specifically (and separately) to meet the requirements and constraints of each device, and the process must be repeated every time the content is updated. Manual reauthoring of content can cause problems for a mobile workforce that depends on getting reliable information. Each time content is rewritten, possibilities for errors exist, and updates may not always be available simultaneously for all devices.
There are two main options for those who want to automate the reformatting of content: using a transcoding server product, such as Aether's Scout Web, AvantGo's Enterprise Server, or IBM's WebSphere Transcoding Publisher, or using a transcoding service, such as Everypath. Although the server products offer the most control over the final content, they also require in-house expertise, as developers must work directly with the original HTML and eXtensible Markup Language (XML) content. Transcoding services are application service providers (ASPs) that take responsibility for the entire process and deliver the reformatted content from legacy material.
There are a number of different ways that transcoding can take place. In one example, the original material (an HTML or XML document, for example) is analyzed by a program that then creates a separate version (rather than changing the source) that contains annotations. The annotations include information that will instruct the reformatting process, such as importance ratings of document elements, for example, so that when space is limited, non-essential elements will not be displayed. When a request for the document is sent to the hosting server, the server submits the annotated version to an authoring application. The material is reformatted there, and sent on to a transcoding proxy server. The proxy server accesses information about device preferences, and may adapt the material further before delivering it to the end user. The device user may also have specific display preferences, either previously set in the device, or chosen at the time that they request the document, so that the document is reformatted dynamically.
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27 Feb 2004
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