This chapter is informational. If you are already familiar with streaming media requirements, players, and protocols, you might want to skip to Preparing to Cache Streaming Media Data.
To understand the requirements for delivering streaming content on your network, it is important to consider key differences and similarities between the HTML-based Web content that is displayed in Web browsers and streaming media Web content that is viewed using streaming media players or browser plug-ins.
The following table contrasts HTML-based content with streaming content.
Table 1. HTML-Based Versus Streaming Content
| Issue | HTML-Based Content | Streaming Content |
|---|---|---|
User Access |
Most Web browsers can display most HTML-based content. |
A media-specific player is required. For information on configuring the QuickTime player, see Configuring QuickTime Media Players to Use Proxy Services. |
File Size |
Most HTML content files are relatively small. |
Most media files are relatively large. This has implications for ensuring you have adequate caching disk space on your appliance and that you have configured the appliance for streaming media objects. For more information, see Managing Disk Space and Streaming Objects. |
Transmission Rate and Time Constraints |
Relatively unimportant If users are patient, they can eventually view the objects. |
The transmission rate is critically important. Media data is time-oriented. Each file has a natural duration; each byte in the file has a predefined time at which it will be played relative to the other bytes in the file. Movie frames and the accompanying soundtrack must be delivered smoothly, at the correct time, and in sync with each other. For help determining whether your network can accommodate streaming media requirements, see Assessing Your Network Bandwidth Capacity, Managing Streaming Bandwidth (Admission Control), and Managing the Total Sessions Allowed. |
Downloading |
Each object is downloaded as a whole and viewed only after the download is completed. |
Objects are viewed as they download. Complete downloads are not required. Users might be interested in only the middle 10 minutes of the file, resulting in only part of the stream being cached. For information on how streaming objects are cached, see Managing the Caching of Streaming Objects. |
Time of Creation |
HTTP content might have been created in the past, or it might be generated based on the browser request. For example, stock quotes are never stored as objects on an origin Web server but are generated on the fly based on specific browser request parameters. |
Streaming objects might be files created in the past, or they might be live transmissions. If you are concerned about freshness of streams in cache, see Managing Streaming Object Cache Freshness. |
Coding |
There is one version of each object. |
There are usually multiple versions of each object, one for each playback bandwidth. |
Media and User Impacts |
After the objects are displayed, the browser and origin Web server do not interact until the user requests new objects. |
Displaying objects requires constant interaction between the media player and the streaming media server, including handling user requests for fast forwarding, pausing, etc. For information on how the appliance handles interruptions and other user requests, see Managing the Caching of Streaming Objects. |