SPECIFICATION
VCACHE is a simple session caching protocol which provides a time buffer between when an upper protocol closes a lower session and when that close is propagated to the lower session.

SYNOPSIS
When a VCACHE session is closed, it is placed in a time-expiration cache. When VCACHE receives subsequent opens (active or passive), it first looks in its cache for sessions with the same hlp and the same remote host. After a configurable amount of time, closed VCACHE sessions will be destroyed and the lower session actually closed.

As an example, VCACHE can be inserted between a UDP server and UDP to prevent UDP sessions from being closed when the server releases all references.

Server sessions (those created as a result of a match between an incoming packet and an openenable) are always cached. If an instantiation of VCACHE is running in symmetric mode, client sessions (those created by an xOpen) will be cached as well. It is reasonable to configure VCACHE in symmetric mode above symmetric (ASYNC realm) protocols and in asymmetric mode above asymmetric (RPC realm) protocols, though this usage is certainly not required.

REALM
VCACHE can be used with either ASYNC or RPC realm lower protocols and assumes the realm of the protocol below it.

PARTICIPANTS
VCACHE passes participants directly to the lower protocol and does not make direct use of any participant information.

CONFIGURATION
VCACHE uses a single lower protocol.

VCACHE recognizes the following ROM options:

vcache symmetric

:

Run this instantiation in symmetric mode.

vcache asymmetric

: Run this instantiation in asymmetric mode (default).

vcache interval n

: Set the timeout interval for n seconds. A cached VCACHE session is eligible to be destroyed if it is idle for n seconds and is guaranteed to be destroyed if it is idle for more than 2 * n seconds.

AUTHOR
Ed Menze