These two patterns are very similar functionally, except Session Facade is server-bound and Business Delegate is client bound. They both provide: -reduced coupling -increased managebility -simpler interface -better performance -cetralized management (SF-resources,BD-exceptions) Can someone (who actually had this on the exam) point out how Sun formulate the question about how to distinguish them and what are the hints? These are simple patterns but it's a very close call. http://developer.java.sun.com/developer/technicalArticles/J2EE/patterns /J2EEPatternsRoadmap.html
Session Facade By meaning facade is some kind of an abstraction. Lets say that when you want to access the a number of entities. Say u r the teacher and u want to see the attendance of students, if u want to see any important notice on the notice board on the site and so on and so forth. you would create a facade so that that object calls all these entities and not you. It does the following - reduces network - helps maintain transaction across entities
BusinessDelegate by definition a delegate refers to a representative. a business delegate is supposed to be a business representative. So if u have a business service available, u would create a business represntative on the presentation layer so that the presentation layer is independent of the business/service layer this - hides the complexity of an application to connect to the business systems - enables easy development since now the presentation layer can work independently of service layer - it can cache data thats on the server side so to as to decrease the round-trip Typically a sytem would be Servlet -- Action Object -- BusinessDelegate -- SessionFacade -- Entities -- Back-End system
Some place where experience helps and certifications dont
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