3. Connected CD Key Features

There are several key features to a successful Connected CD. This chapter describes these features. Chapter 4 discusses these features in greater detail and gives examples of how to implement them.

3.1 Content

By far the most critical part of application development is the creation of compelling content. Interesting and exciting content is what makes a top-selling title. Rich multimedia technologies such as video, 3D modeling, soft MIDI, software signal processing all demand bandwidth usually unavailable via a 28.2kps modem, but are easily handled by a client's high-powered CPU and graphics subsystem. The Connected CD directly addresses this issue by using the CD-ROM to deliver the multimedia content. Content on the CD can consist of stereo audio tracks, full-motion video, high resolution 3D textures...basically any media file that is undeliverable by the Internet.

3.2 ICTWTDICF: I Can't Tell Where The Data Is Coming From

The function of the application is to present data (content) to the user independent of its source or retrieval method. It is important to realize that on a Connected CD, content may be retrieved from CD/DVD-ROM, the local hard drive, the Internet, or some combination of these. The retrieval of this content should be seamless, that is, without jarring the user with different UIs for CD content and remote Internet content.

If content is located on the Internet, it may be helpful to notify the CD-based application's user interface when an attempt is made to access remote data. This is especially useful to users who are paying for ISP services by the minute. The developer may wish to enable certain properties to be user-defined, such as the setting precedence of searching resource locations or distinguishing the source of content by color-coded links. Likewise, if the application is Web-based and needs to access a CD, the user may be alerted ahead of time to insert (or purchase) the CD before selecting a particular link.

3.3 Seamless Connectivity

The success of a Connected CD will depend on how easily and quickly the application connects with little effort on the part of the user. The application should be intelligent enough to determine if the user has an installed connection to the Internet, or if the user needs to set up an ISP account. Also, the application should have the ability to invoke the dial-up method when an Internet resource is requested, and to disconnect when the application has retrieved the necessary data.

3.4 Prefetching and Caching

Citing the lack of sufficient bandwidth as the primary limitation of today's Internet applications is often an oversimplification when the issue is in fact instantaneous bandwidth. It may turn out that the existing Internet connection is capable of transferring content to the client, over the duration that the application is active, in sufficient volume to fully occupy the users attention. The techniques of prefetching, caching, and the web surfer's equivalent of branch prediction can be combined to minimize otherwise wasted connection idle time, and apparent transfer latency. Clever content organization can create opportunities for prefetching and caching data.

3.5 Content Protection

The ISV's business model may require that either, or both, local media-rich content and Internet-based data be protected from unauthorized access. In such a model, a Web-based application could unlock assets on a local CD or DVD-ROM, possibly at a predetermined time concurrent with the release of related material, such as a concert or album release. Likewise, an application running off a CD or DVD-ROM could present a password to unlock a website protected from web surfers who do not posses the application.

3.6 Scalability

To provide the best experience for users while supporting the largest installed base, it is necessary to scale content to take full advantage of the PC's processing and connection speeds. Scalable content can take the form of media compressed at multiple levels of data and frame rates. Another method of creating a scalable application is to use different capabilities of the processor technology.

3.7 Flexibility

Judicious allocation and duplication of content between local storage and the Internet can enable an application to function satisfactorily in the absence of either the local mass storage medium or an Internet connection. The objective should not only be to minimize user disruption and frustration, but to genuinely offer satisfactory, albeit a lesser level, of gratification for their efforts. For example, a Web-based application that accesses a CD-ROM to play a video clip might offer a slide show if the CD-ROM is not present. Likewise, a CD-ROM-based title should still offer local content and functionality to a reduced degree in the absence of the timely data offered by the Internet connection.