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I've few questions: 1. Please give me rough idea about bidirectional association( UML). 2. Is single tier increases managebility or Security? I think both but in Jawaroski mock test ans. is Security 3. In MVC design model Model is represented by session bean and entity (business Logic) view by JSP (presentation layout) control by servelet or Java beans (presentation logic) Is this correct. thanks, shivani
Originally posted by shivani anand: 2. Is single tier increases managebility or Security? I think both but in Jawaroski mock test ans. is Security
From John's notes: Manageability Manageability refers to the ability to manage a system to ensure the health of the system. A single tier or monolithic app would be more manageable from a management perspective than a multi-tier system, but this must be weighed against the possibility of a change rippling through a monolithic app. From Alex Chaffee�s article: One-tier architecture has a huge advantage: simplicity. One-tier applications don't need to handle any network protocols, so their code is simpler. Such code also benefits from being part of an independent operation. It doesn't need to guarantee synchronization with faraway data, nor does it need exception-handling routines to deal with network failure, bogus data from a server, or a server running different versions of a protocol or program. Moreover, a one-tier application can have a major performance advantage. The user's requests don't need to cross the network, wait their turn at the server, and then return. This has the added effect of not weighing down your network with extra traffic, and not weighing down your server with extra work. In jaworski�s question, he is asking the potential advantage of one-tier, so security is a better answer. Hope this helps. Lucy
[This message has been edited by lucy hu (edited November 07, 2001).]
Joined: Aug 21, 2000
Originally posted by shivani anand: 1. Please give me rough idea about bidirectional association( UML).
Association relationship means one class must know about the other in order to perform its work. A navigiability arrow on an association shows which direction the association can be traversed or queried. And multiplicity of an association end is the number of possible instances of the class associated with a single instance of the other end. For example: Unidirectional person ------> address Person objects know about their Address objects, but Address objects don't know about the Person objects that live there. bidirectional person<-----> address the Address class would have required the addition of a Person attribute to perform its work, with corresponding getter and setter operations. See: http://www-106.ibm.com/developerworks/webservices/library/tip-implor/?dwzone=components#h7 Lucy
Joined: Aug 21, 2000
Originally posted by shivani anand: 3. In MVC design model Model is represented by session bean and entity (business Logic) view by JSP (presentation layout) control by servelet or Java beans (presentation logic) Is this correct. thanks, shivani
The model represents the data on which an application is based.The view presents the data represented by the model in a way that�s targeted at a specific type of client.The controller acts as a central point of control to ensure that a Web application runs smoothly with the Model-View-Controller architecture. In blueprint, Figure 4.9 shows a MVC of EJB-centric application. Model: Enterprise Beans View: JSP pages, JavaBeans Components Controller: Session EJB and controller classes. Lucy