Chapter 3 Jaguar and Application Issues

AI Components in Jaguar

When the Component Builder deploys a component into Jaguar, a new component is created in the specified Jaguar package using the Jaguar Java component model. The new component's interface (its methods and their arguments) is described using CORBA IDL.

Application Integrator components are designed to take advantage of the Jaguar instance pooling feature. This section covers the following topics:

Instance Creation

When a client executes methods on a proxy object for an Application Integrator component, Jaguar creates a new instance of a component if the instance pool does not contain any instances available for reuse. If an unused instance already exists in the pool, Jaguar can initialize that instance by calling the activate method and allowing a client application to call a method on the component. During component instantiation, a one-time initialization routine retrieves component property information.

Instance Activation

Jaguar activates an Application Integrator component instance as a result of a client method invocation request. When activated, the component attempts to connect to its target server using the connection properties that you deployed along with the component. Depending on its configuration, the component can obtain its connection from a connection cache defined in Jaguar, or it can open a connection directly to the server.

If an exception occurs during component activation, the exception information is held and returned on the first method call to that instance. The most common reasons for exceptions during component activation result from problems connecting to the server, such as invalid security values, the server being unavailable, and invalid connection properties.

Method Invocation

The method's input parameters (parameters defined with the modes in or inout) are passed to the target stored procedure. After the procedure executes, any result sets are returned to the caller as the return value of the method call, and any output parameters (parameters defined as inout or out) are returned to the caller.

Instance Deactivation

Jaguar deactivates each Application Integrator component instance when it no longer needs to keep that instance associated with the client that caused its activation. During instance deactivation, the connection that was obtained during instance activation is returned to the pool.

Instance Destruction

Jaguar destroys pooled component instances in any of the following circumstances:

A nonrecoverable error occurs during construction, activation, or deactivation (these errors are recorded in the Jaguar server log).
The Jaguar server shuts down.
A component is refreshed.
The component method completes its task, if the client invoked the method using the Jaguar MASP feature.