Developer Concepts

Q41. How to do a language switch in the Masterpage?

A41. Declare a dropdown as usual in the master page. Instead of overriding the InitializeCulture() place the same code in the Application_BeginRequest event handler in the global.asax. It is very similar to InitializeCulture() in the sense that it occurs early and no controls are ready yet. We have a little problem though, now the control is declared in a template and its name and id attributes rendered differently.

Another collection like the form variables collection that is also not originally server collection is the cookies collection. I use the cookie but it can be any of the ways for cross page communication that do not depend on server controls, like profile, session, querystring etc. We cannot use a cookie to carry the culture name value which comes from the dropdown selected item value, because the culture would always be a step behind. It would be set early on but later the dropdown selection change it but the resources for the previous culture come up. So normally only the page containing the dropdown would be a step behind, but because the dropdown is in the master page it appears that the whole site is ALWAYS ONE STEP BEHIND.

If, however, in the cookie, we pass the control name (which is information that never changes, so we can never be behind), instead of the culture name( which we can never keep up with), and then use that key to get the form variable value, we have pieced ourselves a workaround.

in the master page:

In global.asax

void Application_BeginRequest(Object sender, EventArgs e){
string lang = string.Empty;//default to the invariant culture
HttpCookie cookie = Request.Cookies["DropDownName"];

if (cookie != null && cookie.Value != null)
lang = Request.Form[cookie.Value];

Thread.CurrentThread.CurrentUICulture = CultureInfo.GetCultureInfo(lang);
Thread.CurrentThread.CurrentCulture = CultureInfo.CreateSpecificCulture(lang);
}

Notice, there is absolutely no code in any of the content pages. Thats it ten lines of code and we are done for the whole site. This is not complete code, just a tip and trick of using master page and the .net event model to globalize code.

Q42. How to send a mail using System.Net.Mail?

A42. Here is the code...

Imports

System.Net.Mail
Public

Class MailHelper
'''

''' Sends an mail message
'''

''' Sender address
''' Recepient address
''' Bcc recepient
''' Cc recepient
''' Subject of mail message
''' Body of mail message
Public Shared Sub SendMailMessage(ByVal from As String, ByVal recepient As String, ByVal bcc As String, ByVal cc As

String, ByVal subject As String, ByVal body As String)
' Instantiate a new instance of MailMessage
Dim mMailMessage As New MailMessage()
' Set the sender address of the mail message
mMailMessage.From = New MailAddress(from)
' Set the recepient address of the mail message
mMailMessage.To.Add(New MailAddress(recepient))

' Check if the bcc value is nothing or an empty string
If Not bcc Is Nothing And bcc <> String.Empty Then
' Set the Bcc address of the mail message
mMailMessage.Bcc.Add(New MailAddress(bcc))
End If

' Check if the cc value is nothing or an empty value
If Not cc Is Nothing And cc <> String.Empty Then
' Set the CC address of the mail message
mMailMessage.CC.Add(New MailAddress(cc))
End If

' Set the subject of the mail message
mMailMessage.Subject = subject
' Set the body of the mail message
mMailMessage.Body = body

' Set the format of the mail message body as HTML
mMailMessage.IsBodyHtml = True
' Set the priority of the mail message to normal
mMailMessage.Priority = MailPriority.Normal

' Instantiate a new instance of SmtpClient
Dim mSmtpClient As New SmtpClient()
' Send the mail message
mSmtpClient.Send(mMailMessage)
End Sub
End Class

Web.config

DotNet Concepts

Q16. Whats the advantage of Simplified Code Behind model?

A16. The advantage of the simplified code-behind model over previous versions is that you do not need to maintain separate declarations of server control variables in the code-behind class. Using partial classes (new in 2.0) allows the server control IDs of the ASPX page to be accessed directly in the code-behind file. This greatly simplifies the maintenance of code-behind pages.


Q15. What is Simplified Code Behind Model in ASP.NET 2.0?

A15. ASP.NET 2.0 introduces an improved runtime for code-behind pages that simplifies the connections between the page and code. In this new code-behind model, the page is declared as a partial class, which enables both the page and code files to be compiled into a single class at runtime. The page code refers to the code-behind file in the CodeFile attribute of the <%@ Page %> directive, specifying the class name in the Inherits attribute. Note that members of the code behind class must be either public or protected (they cannot be private).

Example

Codebehind

Partial Class CodeBehind_vb_aspx
Inherits System.Web.UI.Page

Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs)
Label1.Text = "Hello " & TextBox1.Text
End Sub
End Class

Inline Code

<%@ page language="VB" CodeFile="CodeBehind_vb.aspx.vb" Inherits="CodeBehind_vb_aspx" %>

Welcome to ASP.NET 2.0!

Enter Your Name:











Q12. What are server controls?

A12. ASP.NET pages can contain server controls, which are programmable server-side objects that typically represent a UI element in the page, such as a textbox or image. Server controls participate in the execution of the page and produce their own markup rendering to the client. The principle advantage of server controls is that they enable developers to get complex rendering and behaviors from simple building-block components, dramatically reducing the amount of code it takes to produce a dynamic Web page. Another advantage of server controls is that it is easy to customize their rendering or behavior. Server controls expose properties that can be set either declaratively (on the tag) or programmatically (in code). Server controls (and the page itself) also expose events that developers can handle to perform specific actions during the page execution or in response to a client-side action that posts the page back to the server (a "postback"). Server controls also simplify the problem of retaining state across round-trips to the server, automatically retaining their values across successive postbacks.

Server controls are declared within an .aspx file using custom tags or intrinsic HTML tags that contain a runat="server" attribute value. Intrinsic HTML tags are handled by one of the controls in the System.Web.UI.HtmlControls namespace. Any tag that doesn't explicitly map to one of the controls is assigned the type of System.Web.UI.HtmlControls.HtmlGenericControl.


Q13. How do server control handle events?

A13. ASP.NET server controls can optionally expose and raise server events, which can be handled by page developers. A page developer may accomplish this by declaratively wiring an event to a control (where the attribute name of an event wireup indicates the event name and the attribute value indicates the name of a method to call).

Sub EnterBtn_Click(Sender As Object, E As EventArgs)
Message.Text = "Hi " & Name.Text & ", wazzup there!"
End Sub



Q14. How to Navigate to another page?

A14. The following sample demonstrates how to use the control to navigate to another page (passing custom query string parameters along the way). The sample then demonstrates how to easily get access to these query string parameters from the target page.




This navigation triggers when a click is made on the hyperlink. If we want navigation to trigger through code, we may use response.redirect(URL) or server.transfer(URL)

Q17. Whats the use of App_Code directory in ASP.NET 2.0?

A17. Just as pages can be compiled dynamically at runtime, so can arbitrary code files (for example .cs or .vb files). ASP.NET 2.0 introduces the App_Code directory, which can contain standalone files that contain code to be shared across several pages in your application. Unlike ASP.NET 1.x, which required these files to be precompiled to the Bin directory, any code files in the App_Code directory will be dynamically compiled at runtime and made available to the application. It is possible to place files of more than one language under the App_Code directory, provided they are partitioned in subdirectories (registered with a particular language in Web.config).

Q18. Can we put code created in different languages in the same App_Code directory?

A18. By default, the App_Code directory can only contain files of the same language. However, you may partition the App_Code directory into subdirectories (each containing files of the same language) in order to contain multiple languages under the

App_Code directory. To do this, you need to register each subdirectory in the Web.config file for the application.











Q19. Whats the difference between Bin folder and App_Code folder?

A19. The Bin directory is like the Code directory, except it can contain precompiled assemblies. This is useful when you need to use code that is possibly written by someone other than yourself, where you don't have access to the source code (VB or C# file) but you have a compiled DLL instead. Simply place the assembly in the Bin directory to make it available to your site.

By default, all assemblies in the Bin directory are automatically loaded in the app and made accessible to pages. You may need to Import specific namespaces from assemblies in the Bin directory using the @Import directive at the top of the page.

<@ Import Namespace="MyCustomNamespace">

Q20. How to register Assemblies in GAC (Global Assembly Cache)?

A20. The .NET Framework 2.0 includes a number of assemblies that represent the various parts of the Framework. These assemblies are stored in the global assembly cache, which is a versioned repository of assemblies made available to all applications on the machine (not just a specific application, as is the case with Bin and App_Code). Several assemblies in the Framework are automatically made available to ASP.NET applications. You can register additional assemblies by registration in a Web.config file in your application.










Note that you still need to use an @Import directive to make the namespaces in these assemblies available to individual pages.

Q21. Can we bind data to Server Controls without writing code in ASP.NET 2.0?

A21. Yes. ASP.NET 2.0 enables a declarative solution for data binding which requires no code at all for the most common data scenarios, such as:
Selecting and displaying data
Sorting, Paging and Caching Data
Updating, Inserting and Deleting Data
Filtering or Master-Details Using Parameters

ASP.NET 2.0 introduces two types of server controls that participate in this declarative data binding model. These two types of data controls handle the complexity of the stateless Web model for data scenarios, so developers don't need to understand page request lifecycle events just to perform data binding. Another benefit of this control-based model is that it can be easily extended to support additional data access storage providers.


Q23. What are data bound controls?

A23. Data-bound controls are UI controls that render data as markup to the requesting client device or browser. A data-bound control can auto-bind to data exposed from a data source and will fetch data at the appropriate time in the page request lifecycle. These controls can optionally take advantage of data source capabilities such as sorting, paging, filtering, updating, deleting, and inserting. A data-bound control connects to a data source control through its DataSourceID property.

You may be familiar with some of the data-bound controls in ASP.NET v1.x, such as DataGrid, DataList, Repeater, and list controls like DropDownList. ASP.NET 2.0 contains several new data-bound controls as well, such as:

GridView Renders data in a grid format. This control is an evolution of the DataGrid control, and can automatically take advantage of data source capabilities.
DetailsView Renders a single data item in a table of label/value pairs, similar to the form view in Microsoft™ Access. This control can also automatically take advantage of data source capabilities.
FormView Renders a single data item at a time in a form defined by a custom template. Renders a single data item in a table of label/value pairs, similar to the form view in Microsoft™ Access. This control can also automatically take advantage of data source capabilities.
TreeView Renders data in a hierarchical tree view of expandable nodes.
Menu Renders data in a hierarchical dynamic menu (including flyouts).

Q24. What is a Master Page? How do we use it?

A24. A Master Page is a page that contains markup and controls that should be shared across multiple pages in your site. For example, if all of your pages should have the same header and footer banners or the same navigation menu, you could define this in a Master Page once, and then all pages associated to this Master Page would inherit those common elements. The advantage of defining the header, footer, and navigation in a Master Page is that these elements need only be defined once, instead of multiple times in duplicate code across the pages in your site.

Defining a Master Page is just like defining a normal page. Master Pages can contain markup, controls, or code, or any combination of these elements. However, a Master Page can contain a special type of control, called a ContentPlaceHolder control. A ContentPlaceHolder defines a region of the master page rendering that can be substituted with content from a page associated to the master. A ContentPlaceHolder can also contain default content, just in case the derive page does not need to override this content. The syntax of a ContentPlaceHolder control is given below:

<%-- ContentPlaceHolder control --%>


<%-- ContentPlaceHolder with default content --%>

Welcome to my florist website!

To differentiate a Master Page from a normal page, a Master Page is saved under the .master file extension. A page can derive from a Master Page by defining a MasterPageFile attribute on its Page directive, as demonstrated below. A page that is associated to a Master Page is called a Content Page.

<%@ Page MasterPageFile="Site.master" %>


Q25. What is a Content Page? How do we use it?

A25. A Content Page can declare Content controls that specifically override content placeholder sections in the Master Page. A Content control is associated to a particular ContentPlaceHolder control through its ContentPlaceHolderID property. A Content Page may only contain markup and controls inside Content controls; it cannot have any top-level content of its own. It can, however, have directives or server-side code.

<%@ Page MasterPageFile="Site.master" %>


Santa Clause will definitely meet you this Christmas!




Q26. How does Content page access a master page?

A26. In addition to overriding content, it is possible for a Content Page to programmatically access its Master Page. A Content Page creates a strongly-typed reference to the Master Page using the <%@ MasterType %> directive, specifying the virtual path to the master page:

<%@ MasterType VirtualPath="Site.master" %>


The Content Page can then reference the Master Page using the Master property of the Page class:

Master.FooterText = "This is my custom footer"
Dim adr As AdRotator = Master.FindControl("MyAdRotator")

In the code example above, FooterText is a public property exposed on the Master Page, while MyAdRotator is a control on the Master Page.

Q27. Can we have multiple number of Master pages in an ASP.NET 2.0 web application?

A27. Yes.


Q28. Can we have multiple SiteMapPath controls in an ASP.NET 2.0 web application?

A28. Yes.

Q33. How do we set the number of Records in a GridView to display?

A33. Use the PageSize property. It Gets or sets the number of records to display on a page in a GridView control.

Q34. What is the TopPagerRow property of a GridView?

A34. Gets a GridViewRow object that represents the top pager row in a GridView control.

Q35. Describe the Hotspot class?

A35. It implements the basic functionality common to all hot spot shapes. Its Namespace: System.Web.UI.WebControls

You cannot directly create instances of the abstract HotSpot class. Instead, this class is inherited by the CircleHotSpot, RectangleHotSpot, and PolygonHotSpot classes to provide the common basic functionality for a hot spot. You must derive from the HotSpot class to create a custom hot spot class that represents a unique shape that you define. However, you can define most shapes using the CircleHotSpot, RectangleHotSpot, and PolygonHotSpot classes. Its used in an ImageMap control

Q38. What is the DataKeyNames property?

A38. An important property that plays a special role in Update and Delete operations is the DataKeyNames property. This property is typically set to the names of fields from the data source that are part of a primary key used to match a given row in the data source. Multiple keys are comma-separated when specifying this property declaratively, although it is common to only have one primary key field. The values of fields specified by the DataKeyNames property are round-tripped in viewstate for the sake of retaining original values to pass to an Update or Delete operation, even if that field is not rendered as one of the columns in the GridView control. When the GridView invokes the data source Update or Delete operation, it passes the values of these fields to the data source in a special Keys dictionary, separate from the Values dictionary that contains new values entered by the user while the row is in edit mode (for update operations). The contents of the Values dictionary are obtained from the input controls rendered for the row in edit mode. To exclude a value from this dictionary, set the ReadOnly property to true on the corresponding BoundField in the Columns collection. If you are using the GridView designer in Visual Studio, the ReadOnly property is set to true for primary key fields by default.


Q40. How do we enabling Caching for a DataSource Control?

A40. To enable caching for the SqlDataSource control (and also ObjectDataSource), set the EnableCaching property to true. You can specify the length of time (in seconds) to store an entry in the cache using the CacheDuration property. You can also set the CacheExpirationPolicy property to either Sliding or Absolute just as you can do from the cache API. Caching is only supported on the SqlDataSource control when the DataSourceMode property is set to "DataSet". For example, if you set CacheDuration to 5 and SlidingExpiration to Absolute, the SqlDataSource will retrieve data from the database on the first request to the page and store this data in the cache. For subsequent requests, the SqlDataSource will attempt to retrieve the cache entry to serve the request without going back to the original database. After 5 seconds (or perhaps earlier, if cache memory pressure is high), the cache entry will be purged and a subsequent request to the page causes SqlDataSource to go back to the database again (repeating the caching process with the new data).

If you instead set CacheDuration to 5 and SlidingExpiration to Sliding, the cached data will have its time-to-live periodically refreshed as long as the data source requests the cached data once every 5 seconds. If a page requests the cached data at least once every 5 seconds, and there is no cache memory pressure, the cached data effectively remains in the cache forever. On the other hand, if no requests are made for the cached data within a 5 second time period, then the cached item is purged and the next time a request occurs the SqlDataSource control will go back to the original database again.

The example below demonstrates caching with the SqlDataSource control. The TimeStamp column updates each time the query is executed, so you can see how often the data is retrieved from the database versus retrieved from the cache. Note that approximately every five seconds, the TimeStamp updates.

Inline Code Example of Caching...

DataTextField="state" Runat="server" />
ConnectionString="<%$ ConnectionStrings:Pubs %>" />




DataSourceID="SqlDataSource1" AutoGenerateEditButton="True" DataKeyNames="au_id"
AutoGenerateColumns="False">















UpdateCommand="UPDATE [authors] SET [au_lname] = @au_lname, [au_fname] = @au_fname, [phone] = @phone, [address] = @address, [city] = @city, [state] = @state, [zip] = @zip, [contract] = @contract WHERE [au_id] = @au_id"
ConnectionString="<%$ ConnectionStrings:Pubs %>" CacheDuration="5" EnableCaching="True">
















Q40. How do we enabling Caching for a DataSource Control?

A40. To enable caching for the SqlDataSource control (and also ObjectDataSource), set the EnableCaching property to true. You can specify the length of time (in seconds) to store an entry in the cache using the CacheDuration property. You can also set the CacheExpirationPolicy property to either Sliding or Absolute just as you can do from the cache API. Caching is only supported on the SqlDataSource control when the DataSourceMode property is set to "DataSet". For example, if you set CacheDuration to 5 and SlidingExpiration to Absolute, the SqlDataSource will retrieve data from the database on the first request to the page and store this data in the cache. For subsequent requests, the SqlDataSource will attempt to retrieve the cache entry to serve the request without going back to the original database. After 5 seconds (or perhaps earlier, if cache memory pressure is high), the cache entry will be purged and a subsequent request to the page causes SqlDataSource to go back to the database again (repeating the caching process with the new data).

If you instead set CacheDuration to 5 and SlidingExpiration to Sliding, the cached data will have its time-to-live periodically refreshed as long as the data source requests the cached data once every 5 seconds. If a page requests the cached data at least once every 5 seconds, and there is no cache memory pressure, the cached data effectively remains in the cache forever. On the other hand, if no requests are made for the cached data within a 5 second time period, then the cached item is purged and the next time a request occurs the SqlDataSource control will go back to the original database again.

The example below demonstrates caching with the SqlDataSource control. The TimeStamp column updates each time the query is executed, so you can see how often the data is retrieved from the database versus retrieved from the cache. Note that approximately every five seconds, the TimeStamp updates.

Inline Code Example of Caching...

DataTextField="state" Runat="server" />
ConnectionString="<%$ ConnectionStrings:Pubs %>" />




DataSourceID="SqlDataSource1" AutoGenerateEditButton="True" DataKeyNames="au_id"
AutoGenerateColumns="False">















UpdateCommand="UPDATE [authors] SET [au_lname] = @au_lname, [au_fname] = @au_fname, [phone] = @phone, [address] = @address, [city] = @city, [state] = @state, [zip] = @zip, [contract] = @contract WHERE [au_id] = @au_id"
ConnectionString="<%$ ConnectionStrings:Pubs %>" CacheDuration="5" EnableCaching="True">

DotNet Concepts

Q1.what are the new features in ASP.NET 2.0?

A1. ASP.NET is a programming framework built on the common language runtime that can be used on a server to build powerful Web applications. The first version of ASP.NET offered several important advantages over previous Web development models. ASP.NET 2.0 improves upon that foundation by adding support for several new and exciting features in the areas of developer productivity, administration and management, extensibility, and performance.

1) New Server Controls: ASP.NET 2.0 introduces many new server controls that enable powerful declarative support for data access, login security, wizard navigation, menus, treeviews, portals, and more. Many of these controls take advantage of core application services in ASP.NET for scenarios like data access, membership and roles, and personalization.

* Data Controls: gridview, detailsview, and formview

* Navigation Controls: treeview, menu, and sitemappath

* Login Controls: login forms, create user forms, password retrieval, and custom UI for logged in users or roles

* Web Part Controls

2) Master Pages: This feature provides the ability to define common structure and interface elements for your site, such as a page header, footer, or navigation bar, in a common location called a "master page", to be shared by many pages in your site.

In one simple place you can control the look, feel, and much of functionality for an entire Web site. This improves the maintainability of your site and avoids unnecessary duplication of code for shared site structure or behavior.

3) Themes and Skins. The themes and skins features in ASP.NET 2.0 allow for easy customization of your site's look-and-feel. You can define style information in a common location called a "theme", and apply that style information globally to pages or controls in your site. Like Master Pages, this improves the maintainability of your site and avoid unnecessary duplication of code for shared styles.


4) Personalization. Using the new personalization services in ASP.NET 2.0 you can easily create customized experiences within Web applications. The Profile object enables developers to easily build strongly-typed, sticky data stores for user accounts and build highly customized, relationship based experiences. At the same time, a developer can leverage Web Parts and the personalization service to enable Web site visitors to completely control the layout and behavior of the site, with the knowledge that the site is completely customized for them. Personalizaton scenarios are now easier to build than ever before and require significantly less code and effort to implement.


5) Localization. Enabling globalization and localization in Web sites today is difficult, requiring large amounts of custom code and resources. ASP.NET 2.0 and Visual Studio 2005 provide tools and infrastructure to easily build Localizable sites including the ability to auto-detect incoming locale's and display the appropriate locale based UI. Visual Studio 2005 includes built-in tools to dynamically generate resource files and localization references. Together, building localized applications becomes a simple and integrated part of the development experience.


6) Administration and Management -- New tools like Configuration API, ASP.NET MMC Admin Tool, Pre-compilation Tool, Health Monitoring and Tracing have been introduced.


Q9. What is precompilation in ASP.NET 2.0? What is a pre-compiled website?

A9. When the first request arrives at your web application there is a mind-numbing amount of work to do. The worker process starts, the runtime initializes, ASPX pages are parsed and compiled to intermediate language, methods are just-in-time compiled to native code - and the list goes on and on. If you want to cut out some of the overhead and improve the startup time of your application, then you’ll want to look at the precompile features in ASP.NET 2.0.

Although pre-compilation will give our site a performance boost, the difference in speed will only be noticeable during the first request to each folder. Perhaps a more important benefit is the new deployment option made available by the precompile - the option to deploy a site without copying any of the original source code to the server. This includes the code and markup in aspx, ascx, and master files.

There are 2 types of pre-compilation:
(i) In Place Precompilation
(ii) Precompilation for Deployment

In Place Precompilation -> By default, ASP.NET dynamically parses and compiles all the ASPX pages in a folder when the first request arrives for a page inside that folder. ASP.NET also needs to compile applicable files in the special folders, like App_Code, on the first request, and any code-behind files associated with ASPX and ASCX files. The runtime caches all the compilation results in order to quickly process later requests, and does not need to recompile again unless someone edits a file. This behavior gives us a great deal of flexibility, including the flexibility to change code and arkup and instantly have the changes reflected in the next browser request.

The price for this flexibility is the performance hit on the first request. Some people have found their ASP.NET applications to be slow starters. These people usually work in the sales department and perform software demos in front of customers. In place pre-compilation makes the “first hit” to a web application and forces all pages and code in the application to compile.

The tool to use for pre-compilation is the aspnet_compiler executable, which you can find in the %WINDIR%\Microsoft.NET\Framework\v2.x.xxxx directory. If we have a web application in the WebSite1 virtual directory under IIS, we could use the following command line to compile the pplication.

C:\Windows\Microsoft.NET\Framework\v2.0.50215>aspnet_compiler -v /Website1

The –v parameter specifies that we are passing a virtual path to our web site. On servers with multiple websites you may need

to use the –m parameter and specify the full IIS metabase path to the application (-m /LM/W3SVC/1/Root/WebSite1).

The pre-compiled code will end up inside of the Temporary ASP.NET File directory, just as it would when the runtime compiles files for a browser request. Inside of the bin directory for the compiled site, you’ll find the assemblies (dll files). The compiler generates special filenames to avoid naming collisions. In the shot below, the dll starting with App_Code contains the code from the App_Code directory – not too surprising. Each folder containing aspx, or ascx files will compile into a dll prefixed with App_Web. The files with a .compiled extension contain XML with information about which original source code file maps to which assembly.

You may find these files in the following location of your computer.
C:\windows\Microsoft.NET\Framework\v2.0.50727\Temporary ASP.NET Files

With the compiled files in place your web application should have a slightly better startup time, but a primary benefit to in place pre-compilation will be the ability to ensure the web application is error free. If you happen to modify a class or web form and leave an error in the file, the aspnet_compiler will fail and display the compiler error. The tool will also display any warnings, but warning will not stop compilation.


Pre-compilation For Deployment --> Pre-compilation for deployment creates an ‘executable’ (no source code) version of your web application. With pre-compilation for deployment you give the aspnet_compiler the path to your source code, and the path to a target directory for the compilation results, like below.

aspnet_compiler -p "C:\MyDevelopment\WebSite1" -v / C:\MyStage