Understanding Asp.Net Ajax Client Library

Introduction

In this article I will discuss a JavaScript object model provided by asp.net ajax framework. First let’s have look on basic JavaScript techniques to create closures and prototype.

Closure

A closure is a function that encapsulates a class.

e.g.

To access class members we can create object of the class just like we do for any other oop language.

e.g.

Prototype

Prototype is another approach for designing classes in JavaScript. This is most preferred approach as it enhances performance. Using prototype method we can design classes as below

e.g.




Now we have seen the prototype method of declaring a class. Object creation, accessing members is same as that of seen for closure.

one might ask what is the difference between closure method and prototype method? Answer is, closure creates members for your object every time it is created but for prototype members are created only once and then simply copied in each n new object. Hence performance wise prototype method is more suitable.

Working With Asp.Net Ajax Library

ASP.Net ajax provide some very useful features for supporting object oriented development.Using these features we can
   - Create namespaces
   - Create classes
   - Create interfaces
   - Create  enumarations
   - Inherit classes and interfaces
   - Use reflections

And much more. Here I will write few basic things which I have studied and which you find as a basic for learning Ajax library

Registering Class with Asp.Net Ajax library

We saw how to create classes using JavaScript prototype approach. Now we have to register this class with Ajax library. How to do that?For doing this first we need to include ASP.Net Ajax control named ScriptManager to our page.(Its just drag and drop from control toolbox). Script manager will automatically include necessary JavaScript libraries for you. Now care must be taken for whatever code we will write it should be written below the script Manager.
For registering class we use registerClass() function.

e.g.



After this step your class is registered with Asp.net Ajax library and can now use inbuilt features provided by Ajax framework like reflection



This will return you a fully qualified name of a class the object belong to. Additional methods are listed below

Creating And Registering Namespace

To register a namespace we use Type.registerNamespace() method.

e.g.



Here if you apply Object.getTypeName() function on object obj then it will return fully qualified name i.e. Animals.Mammals

Inheritance

Inheritance can be achieved using registerClass() method.

Syntax :

            classInstanceVar.registerClass(typeName, baseType, interfaceTypes)

Where,

     typeName = fully qualified name of class
    
     baseType= this is optional parameter. Base class name
    
     interfaceTypes= this is optional parameter.(see it is types not type). Interface name.
     if more than one then separate names using comma.
    
This can be best understood using an example.

e.g.

Implementing Interfaces

Interfaces allow us to implement a common set of methods across multiple classes with less room for error.
Below example shows an interface "IShape" which contain an abstract method named drawShape().I have created IShape interface and a class Circle which implement the interface.

After creating an interface we need to register it with clientside ajax library  using registerInterface() method.(last code line)

Now to implement an interface first give implementation for its method(s) and then inherit the class from interface in registerClass() method.

e.g.

null parameter in registerClass() in above code indicate that there is no base class for this class.
if you run the code you will get the following output

Creating Enumerations

Creating enum types with ajax library is very simple.

first create enum and the register it with ajax library using Type.registerEnum() method. Look at below example where Enum named color is created and registered with Ajax library

References

http://www.asp.net/AJAX/Documentation/Live/ClientReference/Global/TypeClass/TypeRegisterClassMethod.aspx.