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Saturday, January 15, 2011

IBM Interview Questions: Struts workflow

Qu7: What is struts and how ActionServlet works...


Answers:
The following events happen when the Client browser issues an HTTP request.
  • The ActionServlet receives the request.
  • The struts-config.xml file contains the details regarding the Actions, ActionForms, ActionMappings and ActionForwards.
  • During the startup the ActionServelet reads the struts-config.xml file and creates a database of configuration objects. Later while processing the request the ActionServlet makes decision by refering to this object.
When the ActionServlet receives the request it does the following tasks.
  • Bundles all the request values into a JavaBean class which extends Struts ActionForm class.
  • Decides which action class to invoke to process the request.
  • Validate the data entered by the user.
  • The action class process the request with the help of the model component. The model interacts with the database and process the request.
  • After completing the request processing the Action class returns an ActionForward to the controller.
  • Based on the ActionForward the controller will invoke the appropriate view.
  • The HTTP response is rendered back to the user by the view component.