ASP.NET
Part III
51. How do you apply specific formatting to the data inside the cells?
You cannot specify formatting for columns generated when the grid’s AutoGenerateColumns property is set to true, only for bound or template columns. To format, set the column’s DataFormatString property to a string-formatting expression suitable for the data type of the data you are formatting.
52. How do you hide the columns?
One way to have columns appear dynamically is to create them at design time, and then to hide or show them as needed. You can do this by setting a column’s Visible property.
53. How do you display an editable drop-down list?
Displaying a drop-down list requires a template column in the grid. Typically, the ItemTemplate contains a control such as a data-bound Label control to show the current value of a field in the record. You then add a drop-down list to the EditItemTemplate. In Visual Studio, you can add a template column in the Property builder for the grid, and then use standard template editing to remove the default TextBox control from the EditItemTemplate and drag a DropDownList control into it instead. Alternatively, you can add the template column in HTML view. After you have created the template column with the drop-down list in it, there are two tasks. The first is to populate the list. The second is to preselect the appropriate item in the list — for example, if a book’s genre is set to "fiction," when the drop-down list displays, you often want "fiction" to be preselected.
54. How do you check whether the row data has been changed?
The definitive way to determine whether a row has been dirtied is to handle the changed event for the controls in a row. For example, if your grid row contains a TextBox control, you can respond to the control’s TextChanged event. Similarly, for check boxes, you can respond to a CheckedChanged event. In the handler for these events, you maintain a list of the rows to be updated. Generally, the best strategy is to track the primary keys of the affected rows. For example, you can maintain an ArrayList object that contains the primary keys of the rows to update.
55. What is the transport protocol you use to call a Web service?
SOAP. Transport Protocols: It is essential for the acceptance of Web Services that they are based on established Internet infrastructure. This in fact imposes the usage of of the HTTP, SMTP and FTP protocols based on the TCP/IP family of transports. Messaging Protocol: The format of messages exchanged between Web Services clients and Web Services should be vendor neutral and should not carry details about the technology used to implement the service. Also, the message format should allow for extensions and different bindings to specific transport protocols. SOAP and ebXML Transport are specifications which fulfill these requirements. We expect that the W3C XML Protocol Working Group defines a successor standard.
56. What’s a bubbled event?
When you have a complex control, likeDataGrid, writing an event processing routine for each object (cell, button,row, etc.) is quite tedious. The controls can bubble up their eventhandlers, allowing the main DataGrid event handler to take care of itsconstituents.
57. List the event handlers that can be included in Global.asax?
Application start and end event handlers
Session start and end event handlers
Per-request event handlers
Non-deterministic event handlers
58. Can the view state be protected from tampering?
This can be achieved by including an @ Page directive with an EnableViewStateMac="true" attribute in each ASPX file that has to be protected. Another way is to include the <pages enableViewStateMac="true" /> statement in the Web.config file.
59. Can the view state be encrypted?
The view state can be encrypted by setting EnableViewStateMac to true and either modifying the <machineKey> element in Machine.config to <machineKey validation="3DES" /> or by adding the above statement to Web.config.
60. When during the page processing cycle is ViewState available?
The view state is available after the Init() and before the Render() methods are called during Page load.
61. Do Web controls support Cascading Style Sheets?
All Web controls inherit a property named CssClass from the base class System.Web.UI.WebControls.WebControl which can be used to control the properties of the web control.
62. Session state vs. View state:
In some cases, using view state is not feasible. The alternative for view state is session state. Session state is employed under the following situations:
Large amounts of data - View state tends to increase the size of both the HTML page sent to the browser and the size of form posted back. Hence session state is used.
Secure data - Though the view state data is encoded and may be encrypted, it is better and secure if no sensitive data is sent to the client. Thus, session state is a more secure option.
Problems in serializing of objects into view state - View state is efficient for a small set of data. Other types like DataSet are slower and can generate a very large view state.
63. What classes are needed to send e-mail from an ASP.NET application?
The classes MailMessage and SmtpMail have to be used to send email from an ASP.NET application. MailMessage and SmtpMail are classes defined in the .NET Framework Class Library's System.Web.Mail namespace.
64. Why do some web service classes derive from System.Web.WebServices while others do not?
Those Web Service classes which employ objects like Application, Session, Context, Server, and User have to derive from System.Web.WebServices. If it does not use these objects, it is not necessary to be derived from it.
65. How do I initialize a TextBox whose TextMode is "password", with a password?
The TextBox’s Text property cannot be used to assign a value to a password field. Instead, its Value field can be used for that purpose.
<asp:TextBox Value="imbatman" TextMode="Password"
ID="Password" RunAt="server" />
66. Why does the control's PostedFile property always show null when using HtmlInputFile control to upload files to a Web server?
This occurs when an enctype="multipart/form-data" attribute is missing in the <form> tag.
67. How can the focus be set to a specific control when a Web form loads?
This can be achieved by using client-side script:
document.forms[0].TextBox1.focus ()
The above code will set the focus to a TextBox named TextBox1 when the page loads.
68. How does System.Web.UI.Page's IsPostBack property work?
IsPostBack checks to see whether the HTTP request is accompanied by postback data containing a __VIEWSTATE or __EVENTTARGET parameter. If there are none, then it is not a postback.
69. Describe the difference between inline and code behind.
Inline code is written along side the HTML in a page. Code-behind is code written in a separate file and referenced by the .aspx page.
70. What are the new Data Controls in Asp.net 2.0?
Data access in ASP.NET 2.0 can be accomplished completely declaratively (no code) using the new data-bound and data source controls. There are new data source controls to represent different data backends such as SQL database, business objects, and XML, and there are new data-bound controls for rendering common UI for data, such as gridview, detailsview, and formview.
71. What are the new Navigation Controls in Asp.net 2.0?
The navigation controls provide common UI for navigating between pages in your site, such as treeview, menu, and sitemappath. These controls use the site navigation service in ASP.NET 2.0 to retrieve the custom structure you have defined for your site.
72.What are the new Login Controls in Asp.net 2.0?
The new login controls provide the building blocks to add authentication and authorization-based UI to your site, such as login forms, create user forms, password retrieval, and custom UI for logged in users or roles. These controls use the built-in membership and role services in ASP.NET 2.0 to interact with the user and role information defined for your site.
73.What are the new Web Part Controls in Asp.net 2.0 ?
Web parts are an exciting new family of controls that enable you to add rich, personalized content and layout to your site, as well as the ability to edit that content and layout directly from your application pages. These controls rely on the personalization services in ASP.NET 2.0 to provide a unique experience for each user in your application.
74.What are 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.
75.What are Themes and Skins in 2.0, explain usgae scenario?
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.
Part III
51. How do you apply specific formatting to the data inside the cells?
You cannot specify formatting for columns generated when the grid’s AutoGenerateColumns property is set to true, only for bound or template columns. To format, set the column’s DataFormatString property to a string-formatting expression suitable for the data type of the data you are formatting.
52. How do you hide the columns?
One way to have columns appear dynamically is to create them at design time, and then to hide or show them as needed. You can do this by setting a column’s Visible property.
53. How do you display an editable drop-down list?
Displaying a drop-down list requires a template column in the grid. Typically, the ItemTemplate contains a control such as a data-bound Label control to show the current value of a field in the record. You then add a drop-down list to the EditItemTemplate. In Visual Studio, you can add a template column in the Property builder for the grid, and then use standard template editing to remove the default TextBox control from the EditItemTemplate and drag a DropDownList control into it instead. Alternatively, you can add the template column in HTML view. After you have created the template column with the drop-down list in it, there are two tasks. The first is to populate the list. The second is to preselect the appropriate item in the list — for example, if a book’s genre is set to "fiction," when the drop-down list displays, you often want "fiction" to be preselected.
54. How do you check whether the row data has been changed?
The definitive way to determine whether a row has been dirtied is to handle the changed event for the controls in a row. For example, if your grid row contains a TextBox control, you can respond to the control’s TextChanged event. Similarly, for check boxes, you can respond to a CheckedChanged event. In the handler for these events, you maintain a list of the rows to be updated. Generally, the best strategy is to track the primary keys of the affected rows. For example, you can maintain an ArrayList object that contains the primary keys of the rows to update.
55. What is the transport protocol you use to call a Web service?
SOAP. Transport Protocols: It is essential for the acceptance of Web Services that they are based on established Internet infrastructure. This in fact imposes the usage of of the HTTP, SMTP and FTP protocols based on the TCP/IP family of transports. Messaging Protocol: The format of messages exchanged between Web Services clients and Web Services should be vendor neutral and should not carry details about the technology used to implement the service. Also, the message format should allow for extensions and different bindings to specific transport protocols. SOAP and ebXML Transport are specifications which fulfill these requirements. We expect that the W3C XML Protocol Working Group defines a successor standard.
56. What’s a bubbled event?
When you have a complex control, likeDataGrid, writing an event processing routine for each object (cell, button,row, etc.) is quite tedious. The controls can bubble up their eventhandlers, allowing the main DataGrid event handler to take care of itsconstituents.
57. List the event handlers that can be included in Global.asax?
Application start and end event handlers
Session start and end event handlers
Per-request event handlers
Non-deterministic event handlers
58. Can the view state be protected from tampering?
This can be achieved by including an @ Page directive with an EnableViewStateMac="true" attribute in each ASPX file that has to be protected. Another way is to include the <pages enableViewStateMac="true" /> statement in the Web.config file.
59. Can the view state be encrypted?
The view state can be encrypted by setting EnableViewStateMac to true and either modifying the <machineKey> element in Machine.config to <machineKey validation="3DES" /> or by adding the above statement to Web.config.
60. When during the page processing cycle is ViewState available?
The view state is available after the Init() and before the Render() methods are called during Page load.
61. Do Web controls support Cascading Style Sheets?
All Web controls inherit a property named CssClass from the base class System.Web.UI.WebControls.WebControl which can be used to control the properties of the web control.
62. Session state vs. View state:
In some cases, using view state is not feasible. The alternative for view state is session state. Session state is employed under the following situations:
Large amounts of data - View state tends to increase the size of both the HTML page sent to the browser and the size of form posted back. Hence session state is used.
Secure data - Though the view state data is encoded and may be encrypted, it is better and secure if no sensitive data is sent to the client. Thus, session state is a more secure option.
Problems in serializing of objects into view state - View state is efficient for a small set of data. Other types like DataSet are slower and can generate a very large view state.
63. What classes are needed to send e-mail from an ASP.NET application?
The classes MailMessage and SmtpMail have to be used to send email from an ASP.NET application. MailMessage and SmtpMail are classes defined in the .NET Framework Class Library's System.Web.Mail namespace.
64. Why do some web service classes derive from System.Web.WebServices while others do not?
Those Web Service classes which employ objects like Application, Session, Context, Server, and User have to derive from System.Web.WebServices. If it does not use these objects, it is not necessary to be derived from it.
65. How do I initialize a TextBox whose TextMode is "password", with a password?
The TextBox’s Text property cannot be used to assign a value to a password field. Instead, its Value field can be used for that purpose.
<asp:TextBox Value="imbatman" TextMode="Password"
ID="Password" RunAt="server" />
66. Why does the control's PostedFile property always show null when using HtmlInputFile control to upload files to a Web server?
This occurs when an enctype="multipart/form-data" attribute is missing in the <form> tag.
67. How can the focus be set to a specific control when a Web form loads?
This can be achieved by using client-side script:
document.forms[0].TextBox1.focus ()
The above code will set the focus to a TextBox named TextBox1 when the page loads.
68. How does System.Web.UI.Page's IsPostBack property work?
IsPostBack checks to see whether the HTTP request is accompanied by postback data containing a __VIEWSTATE or __EVENTTARGET parameter. If there are none, then it is not a postback.
69. Describe the difference between inline and code behind.
Inline code is written along side the HTML in a page. Code-behind is code written in a separate file and referenced by the .aspx page.
70. What are the new Data Controls in Asp.net 2.0?
Data access in ASP.NET 2.0 can be accomplished completely declaratively (no code) using the new data-bound and data source controls. There are new data source controls to represent different data backends such as SQL database, business objects, and XML, and there are new data-bound controls for rendering common UI for data, such as gridview, detailsview, and formview.
71. What are the new Navigation Controls in Asp.net 2.0?
The navigation controls provide common UI for navigating between pages in your site, such as treeview, menu, and sitemappath. These controls use the site navigation service in ASP.NET 2.0 to retrieve the custom structure you have defined for your site.
72.What are the new Login Controls in Asp.net 2.0?
The new login controls provide the building blocks to add authentication and authorization-based UI to your site, such as login forms, create user forms, password retrieval, and custom UI for logged in users or roles. These controls use the built-in membership and role services in ASP.NET 2.0 to interact with the user and role information defined for your site.
73.What are the new Web Part Controls in Asp.net 2.0 ?
Web parts are an exciting new family of controls that enable you to add rich, personalized content and layout to your site, as well as the ability to edit that content and layout directly from your application pages. These controls rely on the personalization services in ASP.NET 2.0 to provide a unique experience for each user in your application.
74.What are 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.
75.What are Themes and Skins in 2.0, explain usgae scenario?
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.
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