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Hi, My question is addressed to Blueprints' WAF gurus. I wonder why does this WAF contain 3 controllers (Front, Web and EJB)? Which J2EEpatterns do Web Controller and EJB Controller represent? Is EJB container a substitution for Session Facade? I've read all Blueprints materials but was not able to find detailed WAF description. Where does everything come from? Thank you in advance if you can clarify.
Front Controller is the controller processes the Http request. Web Controller is the business delegate in web tier. EJB Controller is the session facade in EJB tier. The reason you feel confused is that Sun used the command pattern to hide the transfer objects. I spent a lot of time to analysis the Pet Store example. Sun should give us detailed UML pictures and code(JSP included).
Joined: Feb 06, 2002
Hi Xiaolin, I like your interpretation of WC and EC but I cannot agree with you. 1) Because of Sun's naming conventions. They would never match Business Delegate - Web Conroller and Session Facade - EJB Controller names. 2) Business Delegate looks up Business Service and invokes its business methods. WC generates events and passes them to EC. You are right it's not possible to find detailed UML diagrams for the Petstore anywhere. BTW you can easily download all petstore source code including JSP from Blueprints site.
For detail WAF in petstore I can u give u idea that how your webtire is gonna worked. Every request passes through Filter class In petstore SignOnFilter and Encoding Filter. >SignOnFilter Class validate login and creating login by using stateless end entity beans. >Also SignOnDAO class by reading signon signon.config file identifies protected and unprotected resources. >Then request chains to EncodingFilter and then to MainServlet for .do type or TemplateServlet for .screen type. For this web container internally uses mappings.xml file.This file is parsed by using XMLDAO. >.do request furture processes to appropriate htmlaction class >If any ejb action is required then it generates event and then event will pass to the EJBController class through WebController class. The event object may be considered as a transfer objectst. >now ejbController identifes which ejb action should be taken. >for generating the screen ScreenFlowHandler class uses screendefiniton.xml file which is parsed by the corresponding dao class. >then it is redirect to the Template servlet. which then generate the appropriate jsp page by using template.jsp file. >and also all the request with the .screen extenstion goes directly to the TemplateServlet.