Components

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Components

Help | Content Gateway | Version 7.8.x

Cache

The cache consists of a high-speed object database called the object store. The object store indexes objects according to URLs and associated headers. The object store can cache alternate versions of the same object, varying on spoken language or encoding type, and can store small and large documents, minimizing wasted space. When the cache is full, the proxy removes stale data, ensuring that frequently requested objects are fresh.

Content Gateway tolerates disk failure on any cache disk. If the disk fails completely, Content Gateway marks the disk as corrupt and continues using the remaining disks. If all cache disks fail, Content Gateway goes into proxy-only mode.

You can partition the cache to reserve disk space for storing data for specific protocols and origin servers. See Configuring the Cache.

RAM cache

Content Gateway maintains a small RAM memory cache of extremely popular objects. This RAM cache serves the most popular objects quickly and reduces load on disks, especially during traffic peaks. You can configure the RAM cache size. See Changing the size of the RAM cache.

Adaptive Redirection Module

The Adaptive Redirection Module (ARM) provides several essential functions. One is to send device notifications for cluster communication interface failover. Another is to inspect incoming packets before the IP layer sees them and readdress them to Content Gateway for processing.

The ARM is always active.

To redirect user requests to the proxy, the ARM changes an incoming packet's address. The packet's destination IP address is changed to the IP address of the proxy, and the packet's destination port is changed according to the protocol used. For example, for HTTP, the packet's destination port is changed to the proxy's HTTP port (usually 8080).

The ARM supports automatic bypass of sites that do not transit properly through a proxy.

The ARM also prevents client request overloads. When there are more client connections than the specified limit, the ARM forwards incoming requests directly to the origin server. See Connection load shedding.

Host database

The host database stores the Domain Name Server (DNS) entries of origin servers to which the proxy connects. Among other information, the host database tracks: