$28.4 THE CLUSTER MODEL OF THE SOFTWARE LIFECYCLE 927 The cluster FEASIBILITY STUDY model of the software lifecycle DIVISION INTO CLUSTERS Cluster 1 Specification Cluster 2 Design Specification Implemen tation Design Cluster n V&V Specification Generali- Implemen tation zation Design Implemen fation V&V VV Generali- Generali- zation zation TIME To avoid divergence,the current states of the various clusters'development must be regularly reconciled.This is the task of integration,best performed at preset intervals,for example once a week.It is the responsibility of the project leader,and ensures that atevery stage after start-up there will be a current demo,not necessarily up to date for all aspects of the system,but ready to be showed to whoever-customers,managers...-needs reassurance about the project's progress.This also serves to remove any inconsistency between clusters before it has had the opportunity to cause damage,reassuring the project members themselves that the pieces fit together and that the future system is taking shape. What makes possible the cluster model's form of concurrent engineering is the set of information hiding properties of the object-oriented method.Clusters may depend on each other,for example a graphical interface cluster may need,for remote display,classes of the communication cluster.Thanks to data abstraction,it is possible for a cluster to proceed even if the clusters on which it depends are not yet finished;it suffices that the specification phase of the needed classes be complete,so that you can proceed on the basis§28.4 THE CLUSTER MODEL OF THE SOFTWARE LIFECYCLE 927 To avoid divergence, the current states of the various clusters’ development must be regularly reconciled. This is the task of integration, best performed at preset intervals, for example once a week. It is the responsibility of the project leader, and ensures that at every stage after start-up there will be a current demo, not necessarily up to date for all aspects of the system, but ready to be showed to whoever — customers, managers... — needs reassurance about the project’s progress. This also serves to remove any inconsistency between clusters before it has had the opportunity to cause damage, reassuring the project members themselves that the pieces fit together and that the future system is taking shape. What makes possible the cluster model’s form of concurrent engineering is the set of information hiding properties of the object-oriented method. Clusters may depend on each other; for example a graphical interface cluster may need, for remote display, classes of the communication cluster. Thanks to data abstraction, it is possible for a cluster to proceed even if the clusters on which it depends are not yet finished; it suffices that the specification phase of the needed classes be complete, so that you can proceed on the basis FEASIBILITY STUDY TIME Cluster 2 Cluster n Cluster 1 Generali￾zation Implemen tation Design Specification V & V DIVISION INTO CLUSTERS Generali￾zation Implemen tation Design Specification V & V Generali￾zation Implemen tation Design Specification V & V The cluster model of the software lifecycle