Process Control › Evaluate Expression Operator

Evaluate Expression Operator

The Evaluate Expression operator delays processing on the branch of a process until a condition that is represented by a Boolean expression evaluates to true. This operator provides a mechanism to pause a process while waiting for a condition to change. The operator is often used to synchronize interdependent processes or to control the use of shared resources that are represented by variables.

The condition is evaluated periodically according to a specified rate. The rate must be long enough to increase CPU usage within acceptable limits. When there is a condition for some minimum known amount of time, the load can be further reduced by putting a Delay operator before the Evaluate Expression operator. An example of this situation occurs when another process uses a resource and the process does not release the resource before a certain time of the day.