June 2001
Intermediate to advanced
320 pages
9h 18m
English
Content preview from Web Caching
Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
Start your free trial
Content Types
Table A-1 shows the breakdown of responses by content type. As you can see, images make up about 60% of all web requests by count and 40% by volume. The top three content types—GIFs, JPEGs, and HTML—account for 95% of all requests and 63% of all traffic volume.
Table A-1. The Most Popular Content Types (IRCache Data)
| Content Type | Count % | Volume % | Mean Size, KB |
|---|---|---|---|
| image/gif | 40.8 | 16.6 | 3.75 |
| text/html | 35.1 | 23.1 | 6.07 |
| image/jpeg | 19.0 | 22.9 | 11.12 |
| text/plain | 1.7 | 2.5 | 13.45 |
| application/x-javascript | 1.5 | 0.2 | 1.45 |
| application/octet-stream | 0.5 | 10.2 | 179.22 |
| application/zip | 0.1 | 8.0 | 684.14 |
| video/mpeg | 0.0 | 3.4 | 761.90 |
| application/pdf | 0.0 | 1.3 | 336.30 |
| audio/mpeg | 0.0 | 2.5 | 1707.70 |
| video/quicktime | 0.0 | 1.2 | 1205.42 |
| All others | 1.1 | 8.1 | 69.60 |
This data is derived from the fifth and tenth fields of Squid’s access.log file. The logs include many responses without a content type, such as 302 (Found) and 304 (Not Modified). All non-200 status responses without a content type have been filtered out. I have not eliminated the effects of popularity. Thus, these numbers represent the percentage of requests made by clients rather than the percentage of content that lives at origin servers.
Figure A-3 shows some long-term trends of the three most popular content types and JavaScript. The percentage of JPEG images remains more or less constant at about 20%. GIF requests seem to have a decreasing trend, and HTML has a corresponding increasing trend. The GIF and JPEG traces are very periodic. The peaks and valleys correspond to weekends and weekdays. ...