3.1.2 Matrix Server Administration Guide

Chapter 17: Advanced Topics 221

and then create a CUSTOM service monitor, specifying the path of the

script as the “user probe script” parameter. This provides not only

verification of the connection, but a degree of content verification.

The

CUSTOM monitor can also include Start and Stop scripts. Suppose the

myservice application caches transactions induced by requests from

external users for later commitment to a back-end database server. You

want to ensure that if a failover occurs, any transactions previously

acknowledged by one server appear as complete to users connecting to

the new server. This is the kind of situation where Start and Stop scripts

are useful.

The Stop script should commit all cached transactions to the back-end

database. The Start script should force an update of your view of the

database from the back-end server.

Then, if the service moves from the primary server to a backup, all

transactions performed on the primary will be sent to the database and

from there to the backup server before connections are directed to the

backup server.

Limit the Servers That Can Join a Matrix

The network secret key controls server access to the matrix. When you

create a matrix configuration, you will specify a password that is used as

the network secret key. Servers must have this password to join the

matrix. When you add a new server to the matrix and import the matrix

configuration to it, the network secret key will be included. See the Matrix

Server Installation Guide for more information.