ETV Cookbook: Walled Garden

The most basic method for creating interactive television is to create a series of web pages which are viewed on a television with a digital cable set top box and navigated with a remote control. The cable system presents a menu similar to a program guide from which the user selects content designed for TV viewing and not linked to the larger Internet. Such content is referred to as a "walled garden".

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SERVES

Users with advanced digital set-tops in selected cable systems.

INGREDIENTS

Cable System with Interactive Set-tops

Web Content

Web Designers and Editors

INSTRUCTIONS

Negotiate Carriage
Currently there are a number ITV of trials running by a variety of players. For PBS member stations it is often easiest to join a PBS trial, but existing relationships with MSOs and vendors can also provide a useful entry. When negotiating, it is recommended that you obtain the necessary hardware and documentation and test them extensively for functionality before agreeing to any deployment.

MSOs are in the business not only of providing cable access to subscribers, but also in providing subscribers to advertisers. Accordingly, space within an MSO's walled garden is a commodity and as such will have an associated value. This will undoubtedly impact deployments as ITV progresses beyond the trial stage.

Learn How Their System Works
When an enhancement is selected by the user, a command is sent in the form of an http protocol command to a server, located either in the cable companies head end or at an address on the Internet. This command can be sent via an external lan or modem connection or a broadband connection riding on the same cable as the video.

Once this request is received by the server, content is sent back down the line to the set top box for viewing by the user. However, some thought must be given to how content is turned from raw code into something viewable on a consumer television set.

Many cable systems currently have an installed base of low powered or "thin client" set top boxes. These boxes generally are not powerful enough to handle graphics tasks such as rendering HTML, so many of these systems use a process called head-end rendering. In a head end rendered system, HTML content is rendered on a server at the cable head-end and is sent to the set top box as a collection of compressed stills. Often this content is pre rendered and cached on a server located at the cable head end for faster retrieval. This requires specialized server hardware at the cable head-end.

In addition to the installed base of lower powered thin clients set top boxes, many MSOs are beginning deployment of higher powered "thick client" set top boxes. These "thick clients" can support advanced middleware capable of rendering HTML content and frequently supporting a variety of multi media content types such as Flash, MPEG, and Java. It is important to note that even though support of these formats is often claimed by manufacturers, there is no guarantee of support on the particular system, or even on the particular deployment of the system that you are authoring for. Always test content that depends on this kind of advanced functionality.

Gather Documentation and Hardware
It is important to have access to all documentation and hardware involved in the trial you are going to participate in as this technology will impact editorial and design decisions as well as technical ones. For more information on technical capabilities of various ITV platforms, see Cookware:Middleware and Cookware:Hardware Platforms. Also see the Nova Walled Garden Case Study.

Determine Optimal Content
Once you have a grip on the capabilities of the system you are creating content for, think about how the technical constraints of the platform impact your project. For example, text must be larger in an ITV environment than on the web, how does this impact your content editorially? Do you really want to try an elaborate (or even basic) JavaScript implementation in this environment? Be sure to study the TV Authoring Guidelines.

Design Content
Having answered the questions above, you are now ready to create the first version of your enhancement. Review your documentation for factors that will affect your content such as color handling and font size and then build your first version. Test your enhancement on either the hardware or emulator provided by the MSO and adjust accordingly. Repeat until stable.

Test on Actual System
Once you have a version of your enhancement that is stable on the provided test hardware/software, you are ready to try it on the MSOs system. Content should be uploaded to the MSO server or the MSO can point their hardware at your server. If at all possible testing should be done at your location. If this is not possible it is suggested that a programmer be sent to the remote location. Trying to trouble shoot content without seeing exactly what is happening on the final platform is not advised.

DIAGRAM