What Is an iIS Process Engine?
Multiple Engine Systems
An iIS system does not need to be limited to a single engine. It can have any number of engines. For example, one engine might be used for testing and another used for production. (see “Production Engines Versus Development Engines” on page 83.)
In other cases, organizational considerations or heavy load conditions might require multiple production engines. While engines can communicate with one
In most cases, different process definitions would be executed on different engines. For example, one process might execute on one engine while a subprocess it invokes might execute on another. If the same process definition is executed on more than one engine (to handle the workload of a large number of client users) then client users would normally be divided up between the engines, each user logging in to only one of the engines.
Multiple engines can run in a single iPlanet UDS environment, or can be spread across a number of connected iPlanet UDS environments. However, there is no mechanism by which one engine can fail over to another. iIS uses a different mechanism to handle engine failover (see “Failover Configuration” on page 33).
Chapter 1 Introduction: iIS Process Management 29
