This article explains the life cycle of Application State; the Global.asax file is also explained with a real-life example.
BackgroundWe all know that the web uses the HTTP protocol and that the HTTP protocol is a stateless protocol, in other words when a client sends a request to the server, an instance of the page is created and the page is converted to HTML format and then the server returns the response and then the instance of the page and the value of the control is destroyed. So if we have a requirement to store the value of controls then a State Management technique is used.IntroductionApplication State is a state management technique. Application State is stored in the memory of the the server and is faster than storing and retrieving information in a database. Session sate is specific for a single user session, but Application State is for all users and sessions. Application State does not have a default expiration period. When we close the worker process the application object will be lost. Technically the data is shared amongst users by a HTTPApplcationState class and the data can be stored here in a key/value pair. It can also be accessed using the application property of the HTTPContext class.Application State Life CycleStep 1 : When the Browser sends a request to the web server and the server receives the the request it first checks the extension to determine whether or not it is ISAPI because this request can only be handled by the ISAPI extension; if the extension is different then the request is handled by the server itself.Step 2 : After receiving the request the Application Manager creates an application domain. In the application domain an instance of the class HostingEnvironment is created that provides access to information about all application resources. Step 3 : After creating the application domain, ASP.NET initializes the basic objects as HTTPContext, HTTPRequest and HTTPResponse. HTTPContext holds objects to the specific application request as HTTPRequest and HTTPResponse.HTTPRequest contains all the information regarding the current request like cookies, browser information and so on and the HTTPResponse contains the response that is sent to the client.Step 4 : Here all the basic objects are being initialized and the application is being started with the creation of the HTTPApplication class.Step 5 : Then events are executed by the HTTPApplication class for any specific requirement. Here is a list of events:Global.asax file: the Global.asax file is used for handling application events or methods. It always exists in the root level. Events are one of the following of the 2 types in the Global application:
The application will be started only once; if 10 users send a request then 10 user sessions are created. The events of the Global.asax file are:
ASP.NET Application State real-life example
Now I am explaining the real-life example. If you want to see the number of users online then we need to use Application State.Step 1 : Open Visual Studio 2010.Step 2 : Then click on "New Project" > "Web" > "ASP.NET Empty Web Application" .Step 3 : Now click on Solution Explorer.Step 4 : Now right-click on "Add" > "New Item" > "Web Form" and add the name of the web form.Step 5 : Now add the Global.asax file. Again go to Solution Explorer and "Add" > "New Item" > "Global Application Class".Step 6 : Now to configure the session we need to use the web.config file as in the following:
Hands on with ASP.Net MVC - Covering MVC 6