Web Container

• A web container is a predefined application provided by a server, it takes care of the dynamic resource of a web application.
• In a java based web applications, servlets and JSP’s are dynamic resources and the runtime support for then at the server will be provided by the container.
• It consoles based java applications a class that contains main method acts as a container for other classes.

For Example:

Class service

{

Void withdraw()

{

---------

---------

}

Void deposite()

{

---------

----------
}
}
Class M
{
Public static void main(String args[])
{
Service s=new service();
s.withdraw();
s.deposite();
}
}

Here M class is providing runtime support for service class so main class is called a container.
In GUI based applications a frame acts as a container for other awt component like button, textField, textArea etc.

Benefits of Container

Life Cycle Management

• Servlets and JSP’s are dynamic resources of a java based application. The servlets or JSP’s will run on a server and at server side, a container will take care about life and death of a servllet / JSP.
• A container will instantiate, initialize, service and destroy of a servlet or JSP. It means life cycle will be managed by a container.

Communication support

If a servlet or jsp wants to communicate with a server than apart from its business logics, some communication logic like socket and streams programming is also required in a servlet / JSP.
Implementing business logic is a burden on a programmer. Adding communication logic on a servlet / JSP will increase more burden on programmers.
To reduce the burden, a container act as a mediator between a server and a server / JSP and provides communication between them.

Multithreading

• A container creates a thread for each request, maintains the thread and finally destroys it
• whenever its work is finished.
• By creating a web application, a programmer is no need of writing threading related logic because of the container.

Security

• Some servlet / JSP’s of a web application are not accessible for all users.
• A programmer is not required to write security code in a servlet / JSP. A container will automatically provide security for a servlet / JSP. If a programmer is informed to the container.