mod_annot editor

Annotate Section

The Apache Proxy Modules

So far, we have spoken loosely of mod_proxy. However, it's a little more complicated than that. In keeping with Apache's modular architecture, mod_proxy is itself modular, and a typical proxy server will need to enable several modules. Those relevant to proxying and this article include:

  • mod_proxy: The core module deals with proxy infrastructure and configuration and managing a proxy request.
  • mod_proxy_http: This handles fetching documents with HTTP and HTTPS.
  • mod_proxy_ftp: This handles fetching documents with FTP.
  • mod_proxy_connect: This handles the CONNECT method for secure (SSL) tunneling.
  • mod_proxy_ajp: This handles the AJP protocol for Tomcat and similar backend servers.
  • mod_proxy_balancer implements clustering and load-balancing over multiple backends.
  • mod_cache, mod_disk_cache, mod_mem_cache: These deal with managing a document cache. To enable caching requires mod_cache and one or both of disk_cache and mem_cache.
  • mod_proxy_html: This rewrites HTML links into a proxy's address space.
  • mod_headers: This modifies HTTP request and response headers.
  • mod_deflate: Negotiates compression with clients and backends.

Having mentioned the modules, I'm going to ignore caching for the remainder of this article. You may want to add it if you are concerned about the load on your network or origin servers, but the details are outside the scope of this article. I'm also going to ignore all non-HTTP protocols, and load balancing.