CODEWITHSUNDEEP
javajspmodel-view-controllerservlets
An SO User
An SO User

Reputation: 24998

Working of MVC architecture for Servlets

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So, yeah, this is what I understood.

Did I get that right?

Upvotes: 3

Views: 6501

Answers (2)

arvin_codeHunk
arvin_codeHunk

Reputation: 2390

When you are talking about MVC, then all three layers should be separated from each other. In web application :

1: A controller should be responsible handling the user request then filtering & executing the appropriate actions and then forward the generated response to the client.

2: A model consist of your Business logic,beans & Pojo classes. This should deal with you logic ,perform some operation and renders the generated result to some kind of persistent object or DTO's.

3: A view is consist of your GUI, some presentation-logic , it should be separated from your back-end ,ultimately you are showing an encapsulated form of result to your client i.e. what a client actually needed.

There are two types of MVC: MVC1(Push-MVC) and MVC2(Pull-MVC)

Pull-MVC and Push-MVC are better understood with how the view layer is getting data i.e. Model to render. In case of Push-MVC the data( Model) is constructed and given to the view layer by the Controllers by putting it in the scoped variables like request or session. Typical example is Spring MVC and Struts1. Pull-MVC on the other hand puts the model data typically constructed in Controllers are kept in a common place i.e. in actions, which then gets rendered by view layer. Struts2 is a Pull-MVC based architecture, in which all data is stored in Value Stack and retrieved by view layer for rendering.

Upvotes: 3

Sean Patrick Floyd
Sean Patrick Floyd

Reputation: 298818

The Model View Controller pattern is not specific to Java or Servlet technology. There are many non-java MVC implementations, and in Java, there are non-Servlet implementations (Swing is an example).

In Java, when using Servlet-based MVC, usually an MVC framework is used. There are two main categories here: action based and component based, the difference being that action based frameworks listen each registered URL independently while component based frameworks keep a component tree and maintain server-side state.

Action based frameworks are Spring MVC, Struts 1+2, Stripes, Play etc. Component based frameworks are Wicket, JSF 1 & 2, Tapestry etc.

Your diagram gets close to the truth, but there are a few subtle misconceptions.

First, it doesn't make sense to speak of .java files. Java source files are totally irrelevant to a deployed web application, it uses compiled .class files only, and the JavaVM can be programmed in many different languages, so the application doesn't care whether the .class files were compiled from Java, Scala, Groovy, JRuby, Clojure, AspectJ or anything else as long as they comply to the Java Class File specification.

Second, while JSP has long been the default view technology in Java Servlet technology, it's far from the only one. Other technologies include Facelets, Velocity, Freemarker etc., and there's also nothing to stop you from writing data directly to a request from a controller without a dedicated view technology (although this is usually not advisable).

Basically, what MVC stands for is a system where there is separate code for business logic (the M), the view technology (V) and the Controller that ties things together. In a well-organized MVC architecture, the M part is so well encapsulated that the same business logic can also be executed through other channels (e.g. web services, direct library access etc.). Also, it should be possible to switch view technologies through configuration from the outside without editing the actual controller logic.

I would advise you to read the docs for the Spring MVC framework, it is to my knowledge the most robust (and also easy-to-use) MVC framework out there, and the tooling support is also great (in either InteliJ Idea or the Eclipse-based SpringSource Tool Suite).

Upvotes: 4

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