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HTTP: The Definitive Guide
book

HTTP: The Definitive Guide

by David Gourley, Brian Totty, Marjorie Sayer, Anshu Aggarwal, Sailu Reddy
September 2002
Intermediate to advanced
656 pages
22h 14m
English
O'Reilly Media, Inc.
Content preview from HTTP: The Definitive Guide

Name

UA-(CPU, Disp, OS, Color, Pixels)

Synopsis

These User-Agent headers are nonstandard and no longer common. They provide information about the client machine that could allow for better content selection by a server. For instance, if a server knew that a user’s machine had only an 8-bit color display, the server could select images that were optimized for that type of display.

With any header that gives information about the client that otherwise would be unavailable, there are some security concerns (see Chapter 14 for more information).

Type

Extension request headers

Notes

These headers are not defined in RFC 2616, and their use is frowned upon.

Basic Syntax

“UA” “-” (“CPU” | “Disp” | “OS” | “Color” | “Pixels”) “:” machine-value

machine-value = (cpu | screensize | os-name |display-color-depth)

Examples

UA-CPU: x86

CPU of client’s machine

UA-Disp: 640, 480, 8

Size and color depth of client’s display

UA-OS: Windows 95

Operating system of client machine

UA-Color: color8

Color depth of client’s display

UA-Pixels: 640x480

Size of client’s display

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Publisher Resources

ISBN: 1565925092Errata Page