Home > Articles > Certification > Microsoft Certification

This chapter is from the book

ASP.NET Application

An ASP.NET application is made up of the Web forms, assemblies, and other files stored within a virtual Web directory marked as an IIS application.

When ASP.NET receives a request for a resource in an ASP.NET application, it instantiates an HttpApplication object. The HttpApplication object then takes over the processing of incoming request. An HttpApplication object can only handle one request at a time. To process multiple simultaneous requests, ASP.NET needs to create multiple HttpApplication objects.

For the sake of optimization, instead of destroying the HttpApplication object, ASP.NET maintains a pool of HttpApplication objects. When a new HTTP request arrives, ASP.NET reuses one of the objects from this pool rather than creating a new HttpApplication object from scratch.

The HttpApplication class defines the methods, properties, and events common to all application objects within an ASP.NET application. If you want to customize the behavior of an HttpApplication object, you can derive a class from the HttpApplication class and override the event handlers of the base class for various application level events. An easy way to do this is by using the global.asax file.

The global.asax File

ASP.NET provides an easy way to customize your applications by using the global.asax file. This optional file resides in the root directory of an ASP.NET application. The global.asax file defines a class named Global that derives from the HttpApplication class. When ASP.NET notices that the global.asax file is present for an application, rather than using the implicitly created HttpApplication object, ASP.NET creates instances of the class defined in the global.asax file to handle requests for your application.

Visual Studio .NET automatically creates a global.asax file when you create an ASP.NET Web application project. As with Web forms, Visual Studio .NET creates a code-behind version of the global.asax file. When you make any changes to the code-behind file for global.asax, you must precompile the file before the server can detect those changes. However, it is also possible to create a single file implementation of the global.asax file. In that case, instead of being precompiled, the global.asax file will be dynamically compiled at runtime by ASP.NET.

The global.asax File Is Protected

You use the global.asax file to provide event handlers for various application level events. For security reasons, ASP.NET restricts users of your application from downloading any file with the extension .asax.

Global Event Handlers

The global.asax file is an appropriate place to handle events that are not specific to a Web form, but rather apply to an application as a whole. I'll call these events global events and classify them in two categories—Application and session level events and Per-Request events.

Application and Session Level Events

Application and session level events are fired to signal the start and end of the application or a user session. These events can be handled using the predefined event handlers in the global.asax file shown in Table 3.8.

Table 3.8 Application and Session Level Event Handlers in the global.asax File

Event Handler



Called when an application receives its first request. Generally used to initialize data that is shared among all users of an application.


Called when an application shuts down. Here you can write code to persist the information stored in memory that you want to have reloaded when the application restarts.


Called when an ASP.NET application creates a new session for a user of the application.


Called when the user's session expires. By default, this happens 20 minutes after the last request of a page from a user.

Per-Request Events

The event handlers shown in Table 3.9 are invoked for each individual page request processed by the HttpApplication object.

Table 3.9 Per-Request Event Handlers

Event Handler



Called at the beginning of each request.


Called when a security module has established the identity of the user.


Called when a security module has verified user authorization.


Called to resolve the current request by providing content from a cache.


Called to associate the current request with the session state.


Called when ASP.NET begins executing a page.


Called when ASP.NET finishes executing a page.


Called to save the current state data.


Called to update a cache with the responses.


Called at the end of each request.

As you can see from Table 3.9, you have complete control over how a request is processed. You can write code in any of these event handlers to modify the default behavior of ASP.NET. Step by Step 3.6 uses the Application_BeginRequest() and Application_EndRequest() methods to determine the time it took for each request to process and append this information with every response.


3.6 Handling Global Events Using the global.asax File

  1. Open the global.asax file from the Solution Explorer. Click on the Click Here to Switch to Code View hyperlink to switch to code view.

  2. Add the following code to the Application_BeginRequest() event handler:

  3. protected void Application_BeginRequest(Object sender,
      EventArgs e)
      // Store the begin time of the 
      // request in the HttpContext object
      this.Context.Items.Add("BeginTime", DateTime.Now);
  4. Add the following code to the Application_EndRequest() event handler:

  5. protected void Application_EndRequest(Object sender,
      EventArgs e)
       // Get the begin time from the HttpContext object
       DateTime dtBeginTime = 
       (DateTime) this.Context.Items["BeginTime"];
      // Calculate the time span between 
      // the start and end of request
      TimeSpan tsProcessingTime = 
      // Display the processing time taken 
      // by the response
       "{0} took {1} milliseconds to execute.",
  6. Run the project. You should see that the page shows a message at the bottom indicating the processing time of the request, as shown in Figure 3.7.

Figure 3.7Figure 3.7 The global.asax file gives you access to application-level events that affect all the pages in an application.

In Step by Step 3.6, the Context object is used to store the begin time. The Context object exposes a key-value collection via the Items property in which you can add values that will be available for the life of the current request. The Context object gives access to the current HTTP request and response.

The modification of the global.asax file in Step by Step 3.6 will affect all other Web forms in the Web application 315C03. If at a later stage, you would like to disable the output generated by the global events, just comment the corresponding lines in the global.asax file.


  • ASP.NET maintains a pool of HttpApplication objects. When a new HTTP request arrives, ASP.NET uses one of the objects from this pool rather than creating an HttpApplication object from scratch.

  • The global.asax file can be used to define a customized HttpApplication class. When the global.asax file is defined in the Web application's root directory, ASP.NET uses the HttpApplication-derived class defined in the global.asax file to serve the Web application.

  • The global.asax file is an appropriate place for handling global events that are not specific to a Web form, but rather apply to an application as a whole.

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.


Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.


If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.


This site is not directed to children under the age of 13.


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020