Parallel Object–Oriented Pattern Catalogue

Method Sequence prefix() executeSequence() suffix() Abstract Method Facade firstPhase() secondPhase() thirdPhase() . . . lastPhase() facade Method Sequence prefix() suffix() Method Facade firstPhase() secondPhase() thirdPhase() . . . lastPhase() Figure 4: The structure of the Method Sequence pattern using OMT notation. suffix() This method is invoked after the sequence has completed executing. It can be used for any cleanup required by the sequence or facade objects, or can be used to invoke other parts of a larger program (including other parallel patterns). In the PSRS algorithm, this method may be used to verify that the data is properly sorted. By default, this method does nothing. The hook methods for the Facade object in the Method Sequence pattern are the methods listed in the last pattern parameter. By default, these methods do nothing. 2.7 Structure and Participants The structure of the Method Sequence pattern, using OMT notation, is given in Figure 4. The key participants in the Method Sequence pattern are the following: Abstract Method Sequence This abstract class is responsible for implementing the structure of the pattern. In the Method Sequence pattern, it has methods for executing the sequence of methods on an instance of Abstract Method Facade. It also provides default implementations of all hook methods. Method Sequence This concrete class allows users to implement hook methods and extend the pattern with additional methods. The user implements hook methods by overriding the default implementation from the abstract superclass. Additional methods can also be added, and the constructors can be augmented to include new parameters1. Abstract Method Facade This abstract class provides the structure for the Facade object. It provides a default constructor and the default implementations of the hook methods. Method Facade This class is the receiver object for the methods in the sequence. The user uses this class to implement hook methods, add new methods, and augment constructors. This class is also responsible for storing partial 1This is not true of all concrete classes, since some objects are created as part of the parallel structure which, at the highest level of abstraction of CO2P3S, cannot be modified. 6 main program Method Sequence Method Facade executeSequence() prefix() suffix() firstPhase()