Essential Framework Design Patterns

} Simulation time: long actors: SortedQueue Simulation() schedule(a: Actor, time: long) simulate(duration: long) reset() * 0 manages Figure 6 Essential construction principles + hot spots = domain-specific design patterns Hot spot identification can be supported by hot spot cards, a communication vehicle between domain experts and software developers. Pree (1996) presents the concept of hot spot cards and detailed case studies where they are applied. A further reason why explicit hot spot identification helps, can be derived from the following observations of influencing factors in real-world framework development: One seldom has two or more similar systems at hand that can be studied regarding their commonalities. Typically, one too specific system forms the basis of framework development. Furthermore, commonalities should by far outweigh the flexible aspects of a framework. If there are not significantly more standardized (= frozen) spots than hot spots in a framework, the core benefit of framework technology, that is, having a widely standardized architecture, diminishes. As a consequence, focusing on hot spots is likely to be more successful than trying to find commonalities. 4 Outlook Above we discussed technical aspects of framework development by presenting the fundamental framework design patterns. But organizational measures are at least equally important to be successful as framework development requires a radical departure from today’s project culture. Goldberg and Rubin (1995) present these aspects in detail. Essential Framework Design Patterns 7 Overall framework development does not result in a short-term profit. On the contrary,frameworks represent an investment that pays off in the long term. But we viewframeworks as the long-term players towards reaching the goal of developing softwarewith a building-block approach. Though the state of the art still needs profoundrefinement, many currently existing frameworks corroborate that frameworks will be theenabling technology in many areas of software development.A word of advice for those who have not worked with frameworks so far: Nomethodology or design technique will help avoid this painful learning process. Toyaround with some of the available large-scale frameworks and get a better understandingof the technology by first reusing frameworks before jumping into frameworkdevelopment. 5 ReferencesGamma E., Helm R., Johnson R. and Vlissides J. (1995). Design Patterns—Elements of ReusableObject-Oriented Software. Reading, Massachusetts: Addison-WesleyGoldberg A., Rubin K. (1995). Succeeding with Objects—Decision Frameworks for ProjectManagement. Reading, Massachusetts: Addison-WesleyLewis T. et al. (1995). Object-Oriented Application Frameworks. Greenwich, CT: ManningPublications/Prentice Hall.Pree W. (1995). Design Patterns for Object-Oriented Software Development. Reading, MA: Addison-Wesley/ACM PressPree W. (1996). Framework Patterns. New York City: SIGS BooksWirfs-Brock R. and Johnson R. (1990). Surveying Current Research in Object-Oriented Design.Communications of the ACM, 33(9)