Concurrency for EAS Components
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Description

In Jaguar Manager, you can change the Concurrency property of a component on the Instances tab page of the component's property sheet. For PowerBuilder components, the Concurrency property determines whether multiple instances of a component can be created to handle multiple client requests. You can now set this property in the Project painter.

Each instance of a PowerBuilder component executes in its own session, and each session can only support one thread of execution. Therefore a single PowerBuilder component instance cannot simultaneously execute multiple client requests. However, multiple instances of the same component can each execute a separate client request. The preferred value for this property depends on whether the component is a standard, shared, or service component.

Usage

The Concurrency property is available on the Components page of the EAServer Component Generator property sheet in the Project painter. Checking the Concurrency checkbox sets the com.sybase.jaguar.component.thread.safe property to TRUE.

For standard components, you can improve performance by allowing multiple instances of a component to handle client requests. The default setting for standard components is checked, but you can change the setting if you only want one instance of a given component.

For shared components, only one instance of the component should be active at any time and therefore only one thread can be executed. The Concurrency checkbox is disabled and not checked for shared components.Although service components are usually treated as shared components, you can choose to create more than one instance of a service component to improve performance and scalability. There are three options on the Components page that interact for service components: Concurrency, Automatic Demarcation/Deactivation, and Create Instances (the Create Instances option can only be changed for service components).

When you change the Create Instances option to 2 or more, the Concurrency checkbox and the Automatic Demarcation/Deactivation checkbox become checked. Multiple instances of the service component can be created if necessary, and are deactivated after each method call. If you clear the Automatic Demarcation/Deactivation checkbox, so that you need to explicitly deactivate component instances, the Create Instances checkbox is reset to 1.

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