org.lsst.ccs.messaging.mock

Interface CommandFor<T>

public interface CommandFor<T>

This interface defines the behaviour of a class implementing a Command pattern.

Example:

Lets define a class Doer that has a method show(String string, int anInt). When do we need to send a "command" to such an Object instead of just calling directly this method? It could be that the code that "relays" this invocation does not know much about the sender , the receiver and the method itself.
for instance we may want to send a "command" to such an Object through the wire and invoke the method across the network (without predefined RMI) or we have a generic code that dispatches a call to many receivers.
In programming parlance we are going to "reify" the method call: that is transform it into an Object.
So the object representing this method call and implementing the Command could look like that:

          class ShowCommand implements CommandFor , Serializable{
              String arg1 ;
              int arg2 ;
              // constructor and everything
              public void invokeOn(Doer someInstance) {
                  someInstance.show(arg1, arg2)
              }
          }
      

Now suppose the receiving code reads the command from a Stream

          Doer actor ; // initialized
          // then later
          ShowCommand command = (ShowCommand) objectStream.readObject() ;
          command.invokeOn(actor); // and that's it!
      

Author:

bernard Amade

See Also:

org.lsst.ccs.utilities.dispatch.SynchronousCommandFor, org.lsst.ccs.utilities.dispatch.SynchronousCommandDispatcher, org.lsst.ccs.utilities.dispatch.ParallelCommandDispatcher

Method Summary

Modifier and Type	Method and Description
void	invokeOn(T instance)

Method Detail

invokeOn

void invokeOn(T instance)