In real-time we may come across scenario where depending on the particular group of users we need to show different layout, colors, themes, functionalities and so on. To achieve this there are various ways, maintain the settings for each user in table , maintain the cookies and so on.

 In .net the best way to achieve this is to change master page dynamically where the master pages will have different layout , different look and feel for different users.  This we can achieve by following below mentioned steps.

1.       All the WebPages will be inherited form System.UI.Web.Page base class

2.       In page directive we  have a property to set masterpage file

3.       Once we attach any master page to any child, first all the controls of the master page are instantiated, then child page controls are instantiated

4.       If we want to apply master page in code behind file ,the page’s master page property needs to be applied in Onpreinit method only.

5.       After instantiating controls, child page load will be called first, then the master page will be loaded.

To change master page dynamically we need to follow the below mentioned process/method

1.       Create one separate class file as public, which will inherits System.UI.Web.Page base class

2.       Override the Page base class method onPreinit(), in this method set the master page property of the page, give the name of the master page file which you want to apply

3.       At the end of the onPreinit() method call the base class onpreinit method

4.       Inherit the newly created class in all of your web pages.

5.       To provide the custom master page, we may use cookies, sessions or the values stored from database, it depends on how we want to manage the customization.

Illustration

The use cases and class diagrams are very useful in order to plan and designing any project. Before understanding use cases and diagrams we need to know regarding UML.

UML can be abbreviated as Unified Modeling Language, which is used in order to provide a common modeling for various
problems/projects which are platform independent, technology independent and support purely object oriented programming languages.

The use cases can be defined in simple word as scenario in which the given problem solution will be used and what are all the cases that may arise while using the project/solution.

The use cases helps the system design and development easier by providing the necessary and mandatory cases that are the users of any project.  The use cases can be represented by using standard notations.  The following are the notations which are used in order derive the use cases most commonly.

In order to understand the use cases in better way, let me explain an example, consider the video conference system as a problem/project, in order to implement this project first I need to gather the information from user/client properly once the required information is gathered by using any of the information gathering techniques, I can start on writing the use cases for video conference system.

The use cases are formed or designed by considering the main functional requirements of the system not mapped one-to-one and it shows what behavior the actor can expect and not how the system will work to provide the service.

In order to write the use cases we need to know two things properly in use cases

1.  Actor,the external agent who will make use of the system

2. Service provided by the System

In the video conference system the actors are the persons who will make use of the system by connecting to the system, and the services provided by the system are login authentication, video conferencing, video recording, text messaging.  These are all the main functional requirements which are identified in order to develop the video conferencing system.  The following are the different use cases those can be derived or drawn by considering the video conferencing system and the services provided by the system.

The following are the example/illustrative use case diagrams with respect to web based video conferencing system, which is used for video conferencing over the internet.

The use case diagrams does have extension, aggregation and interface concept those can be represented pictorially as above.

Class Diagrams

                The class diagrams are diagrams which are used in order to represent the classes used or to be used in any solution
implementation using notations.  The class diagrams makes the understandability of the project flow and the pictorially represents the different classes used and how they were connected to each other  and which are all the classes that depends on the other classes can be represented.

The class diagram can be represented by following notation and it does mainly have 3 parts first part is the name of the class, the second box or part is declaration of members or variables which are used in the class, the third part/box will be list of all the methods which are implemented in the class in order to perform the operations on class data members.

The following notations are used in drawing class diagrams.

The Class diagrams can be used to represent all the available variants of classes in Object oriented languages.

The example class diagram used in web based video conferencing system.

In this diagram, as we can see the class is of type public and class name is enter_002dconf2_jsp used in web based video conferencing system, the member of the class is _dependants of  type Vector and access mode is private.

The two methods are defined of type public in order to perform the required operation, the getDependants() ,
method will get all the necessary dependents needed to start the video conferencing service, and the second method will _jspService() will start the service and write the required information on to the browser, if the required dependents are present then the client application will run through which the user can able to perform video conferencing, if not then the
necessary information will be written on to the browser.