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The Apache HTTP Server Reference Manual
by Apache Software Foundation
Paperback (6"x9"), 862 pages
ISBN 9781906966034
RRP £19.95 ($29.95)

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8.1  Introduction

As of Apache HTTP server version 2.2 mod_cache and mod_file_cache are no longer marked experimental and are considered suitable for production use. These caching architectures provide a powerful means to accelerate HTTP handling, both as an origin webserver and as a proxy.

mod_cache and its provider modules mod_mem_cache and mod_disk_cache provide intelligent, HTTP-aware caching. The content itself is stored in the cache, and mod_cache aims to honour all of the various HTTP headers and options that control the cachability of content. It can handle both local and proxied content. mod_cache is aimed at both simple and complex caching configurations, where you are dealing with proxied content, dynamic local content or have a need to speed up access to local files which change with time.

mod_file_cache on the other hand presents a more basic, but sometimes useful, form of caching. Rather than maintain the complexity of actively ensuring the cachability of URLs, mod_file_cache offers file-handle and memory-mapping tricks to keep a cache of files as they were when Apache was last started. As such, mod_file_cache is aimed at improving the access time to local static files which do not change very often.

As mod_file_cache presents a relatively simple caching implementation, apart from the specific sections on CacheFile and MMapFile, the explanations in this guide cover the mod_cache caching architecture.

To get the most from this section, you should be familiar with the basics of HTTP, and have read the Users’ Guides to Mapping URLs to the Filesystem (p. 142) and Content negotiation (p. 1423).

ISBN 9781906966034The Apache HTTP Server Reference ManualSee the print edition