Acting as a reverse proxy, or a forward proxy, Caching Proxy intercepts data requests from a client, retrieves the requested information from content-hosting machines, and delivers that content back to the client. Most commonly, the requests are for documents stored on Web server machines (also called origin servers or content hosts) and delivered via the Hypertext Transfer Protocol (HTTP). However, you can configure Caching Proxy to handle other protocols, such as File Transfer Protocol (FTP), and Gopher.
Caching Proxy stores cacheable content in a local cache before delivering it to the requester. Examples of cacheable content include static Web pages and JavaServer Pages (JSP) FILES with dynamically generated but infrequently changing fragments. Caching enables the Caching Proxy to satisfy subsequent requests for the same content by delivering it directly from the local cache, which is much quicker than retrieving it again from the content host.
IMPORTANT: Caching Proxy is available on all Edge component installations, with the following exceptions:
The two basic proxy configurations are reverse proxy and forward proxy.
By default, Caching Proxy is configured as a reverse proxy server. In a reverse proxy configuration, a proxy server is located between one or more content servers and the Internet. It accepts requests from Internet clients for content stored on the proxy server's home site. The proxy server appears to the client to be the origin (content) server; the client is not aware that the request has been sent to another server.
Alternatively, you can configure Caching Proxy as a forward proxy server. However, client browsers must be individually configured to use the proxy. In a forward proxy configuration, a proxy server is located between the client and the Internet. Caching Proxy forwards a client's request to content hosts located across the Internet, caches the retrieved data, and delivers the retrieved data to the client.
The following changes in the ibmproxy.conf configuration file should be made to enable the forward proxy configuration:
Proxy http:* Proxy ftp:* Proxy gopher:*
SSLTunneling OnFor more information on SSL tunneling, see Configuring SSL tunneling.
Enable CONNECT OutgoingPorts Allor
Enable CONNECT OutgoingPorts 443
For information on the format and available options for the Enable CONNECT method, see Configuring SSL tunneling.
Making these changes allows the forward proxy to do the following:
A variation of the forward Caching Proxy is a transparent Caching Proxy. In this role, Caching Proxy performs the same function as a basic forward Caching Proxy, but it does so without the client being aware of its presence. The transparent Caching Proxy configuration is supported on Linux systems only.
As with regular forward Caching Proxy, the transparent Caching Proxy is installed on a machine near the Internet/gateway, but client browser programs are not configured to direct requests to a forward Caching Proxy. Clients are not aware that a proxy exists in the configuration. Instead, a router is configured to intercept client requests and direct them to the transparent Caching Proxy.
For information on the directive for this configuration, see TransparentProxy -- Enable transparent proxy on Linux.
The Version 6.1 Caching Proxy Administration Guide includes newly documented features and corrective updates.
The most significant features are:
For information on configuring a forward proxy, see Forward proxy.
For information on the transparent (forward) proxy directive, see TransparentProxy -- Enable transparent proxy on Linux.
For information on these methods, see Enable WebDAV methods, MS Exchange methods, and User-defined methods.
For information on these directives, see CompressionFilterAddContentType -- Specify the content type of HTTP response you want to compress and CompressionFilterEnable -- Enable the compression filter to compress the HTTP responses.
For information on this directive, see NoCacheOnRange -- Specify no caching for Range requests.
For information on this directive, see OptimizeRuleMapping -- Optimize the rule mapping process for incoming requests when the number of rules increases.
Similar to the Map directive, MapQuery uses both the path and query string to match the rule.
For information on this directive, see MapQuery -- Change matching requests to a new request string, using the request path and query string to match the rule.
For information on this directive, see RuleCaseSense -- Maps requests from application URLs that are not case sensitive.
For information on these directives, see PKCS11DefaultCert, PKCS11DriverPath, PKCS11TokenPassword -- Supports IBM 4960 PCI Cryptographic Accelerator Card (AIX only).
For information on the logical expression option on this directive, see SSLCertificate -- Specify key labels for certificates.
Caching Proxy provides directives that require additional pattern matching at runtime. To improve the Caching Proxy performance, you can use these directives as options in the Proxy or ProxyWAS rule. For more information on these additional options for Proxy or the ProxyWAS rule, see Proxy -- Specify proxy protocols or reverse proxy.