1. Request :
information coming into the Web server from the browser
called as input object .
represents an HTTP request before it has been sent to the server.
2. Response :
information going out from the server to the browser called as output object.
represents a valid HTTP response that was received from the server.
response header properties are read-only.
3. Server :
An Event is a message. The browser sends a "message" to the server with each Request. The Event can be communicated to the
server in the Request. And the server can then render the appropriate HTML back to the browser according to the Event
Handler, thus having the browser "react" to the Event as well.
4. Session :
These are hash tables in the memory with a timeout specified for which a particular user interacts with a web pages such as forums, or e-commerce websites and wants to keep track of the products ordered.
During a session the unique identity of the user is maintained internally.
It ends if there is a session timeout or if you end the visitor session in code.
These can be done on a per user basis, via the use of session objects.
It helps to preserve data across successive accesses.
These are identified using 32-bit long integers known as Session IDs.
ASP engine generates these session ID’s so that uniqueness is guaranteed.
5. Application :
sessions help to preserve data per user basis. Application is used to initialize variables that are present in a session for all users.
Application variables changed are reflected in the current sessions of all users. For example, we may wish to fix some
variables like tax rate, discount rate etc., that will be specified once for all variables we can access in a session.
At any particular instant, multiple sessions might be trying to change the value, although only one session can be allowed to change it.
ASP.NET has an in-built mutual exclusion for these types of problems.
– Locks the application variables
– Unlocks the application variables
Once application variables are locked sessions that attempt to change them have to wait