Use the Java IDL compiler to process the interface. Inspect the definition of the signatures for the methods pairIn and readPair in the generated Java equivalent of the IDL interface. Look also at the generated definition of the holder method for the value argument for the methods pairIn and readPair. Now give an example showing how the client will invoke the pairIn method, explaining how it will acquire the value returned via the second argument.

Question

What will be an ideal response?

Answer 1

The Java interface is:
```
public interface TaskBag extends org.omg.CORBA.Object {
void pairOut(in Key p, in Value value);
void pairIn(in Key p, out ValueHolder value); void readPair(in Key p, out ValueHolder value); int numberOfTasks();
}

The class ValueHolder has an instance variable

public Value value;

and a constructor

public ValueHolder(Value __arg) {
value = arg;
}
```
The client must first get a remote object reference to the TaskBag (see Figure 20.5). probably via the naming service.
```
...
TaskBag taskBagRef = TaskBagHelper.narrow(taskBagRef.resolve(path)); Value aValue;
taskbagRef.pairIn(“Some key”, new ValueHolder(aValue));
```
The required value will be in the variable aValue.