Question

Visit a popular Web site and discuss what types of exception handling techniques might be used for their Web forms. Make sure to include a link to the web site you discuss.

Write 300-350 words. DUE IN 3 HOURS PLEASE HURRY.

Answer 1

Ans
first of all there is a need to understand that what is exception and what is exception handling.
there are several aspect of a good program such as
1)program reliability
2)coupling
3)readability
4)self documenting code
5)portability
and
6)Robustness
yes, program should be robust, it means that if program receives some improper input,program should not be terminated abnormally, there should be a proper message for a user to indicate the mistake made by the user about the input supplied by the user.

a robust program is not terminated abnormally even if program receives improper input.
so in case of improper input, program is terminated abnormally, such a program is called robust.

exception is a situation which forces a program to be terminated abnormally.
take the example of a program which performs division between two integers.
c=a/b, here the logic is correct but if user supplies b=0(incorrect input for divisor),then the result is infinite and program will be terminated abnormally.
so there will be a exception "Divide by Zero Error".

to handle this exception,before the processing, there should be an arrangement to deal with divisor if divisor is zero. making such types of arrangements to deal with improper inputs is called exception handling.

so with the help of exception handling it is possible to make a program robust.

Exception handling techniques used for web forms
in case of a web application exceptions are handled at following levels

a)Application level:-

Application means a complete web site.it means scope of error is not limited to a single page.
it is at application level.
it means exceptions are handled at global level by adding Application_Error handler.

b)Page Level:-

At Page level, exceptions are handled by redirecting the user to an error page displaying a proper error message. All the objects( such as textboxes, listboxes ) that are supposed to be rendered on the page will not be visible, only error is displayed

apart from these there may be a code level error.

Exceptions can also be tracked by the custom logger.

in a web form the most important issue is to deal with exceptions related to database.
for example
insert operation may attempt to insert a duplicate record in data base table.
for example
two users can not have same user name.
to avoid this conflict, user_name should be declared as primary key in database table.
if a user attempts to insert a user name which is already present in database table .
there will be an exception and should be handled by the program in elegant manner without terminating abnormally.