<p> Programming Right From the Start with Visual Basic.NET</p><p>CHAPTER 13</p><p>Advanced Web Forms with Databases</p><p>True-False Questions</p><p>1. ADO.NET and ASP.NET are tools used to create three-tier application architecture. Answer: True Level: Easy Section: 13-1 Page: 345</p><p>2. The typical three-tier architecture has the database as the middle tier. Answer: False Level: Easy Section: 13-1 Page: 345</p><p>3. A medium client refers to the application layer. Answer: False Level: Moderate Section: 13-1 Page: 345</p><p>4. The logical layer acts as a mediator between the user and the database. Answer: False Level: Moderate Section: 13-1 Page: 345</p><p>5. A web browser is a good example of a thin client. Answer: True Level: Easy Section: 13-1 Page: 345</p><p>6. Business logic stored in a web server module is easy to maintain and modify. Answer: True Level: Moderate Section: 13-1 Page: 345</p><p>7. A disadvantage of using an application layer is that the number of connections is less than if users connected directly with the database. Answer: False Level: Moderate Section: 13-1 Page: 345</p><p>8. The three-tier architecture can help to conserve network and server resources. Answer: True Level: Moderate Section: 13-1 Page: 346</p><p>9. No more than two computers may be placed in a server farm. Answer: False Level: Easy Section: 13-1 Page: 346</p><p>10. A three-tier architecture can exist on a single computer. Answer: True Level: Easy Section: 13-1 Page: 346</p><p>13 - 1 Chapter 13 – Advanced Web Forms with Databases</p><p>11. The two types of methods for tracking the state of a web page are client-side and data-side. Answer: False Level: Easy Section: 13-2 Page: 346</p><p>12. A web server needs special techniques to know the state of previous web pages. Answer: True Level: Easy Section: 13-2 Page: 346</p><p>13. The only way to store information about the state of a web page is to store it on a client machine. Answer: False Level: Easy Section: 13-2 Page: 346</p><p>14. Client-side state management techniques cannot be changed by the end user. Answer: False Level: Easy Section: 13-3 Page: 346</p><p>15. The view state is always stored on the client machine. Answer: False Level: Moderate Section: 13-3 Page: 347</p><p>16. The information about a page’s view state is visible in the HTML source. Answer: True Level: Moderate Section: 13-3 Page: 347</p><p>17. The length of a query string is limited to 128 characters. Answer: False Level: Easy Section: 13-3 Page: 347</p><p>18. A query string is information stored at the end of a URL. Answer: True Level: Easy Section: 13-3 Page: 347</p><p>19. Query strings are the most secure type of state management technique. Answer: False Level: Moderate Section: 13-3 Page: 347</p><p>20. Using cookies is unreliable because users can refuse to have them stored on a machine. Answer: True Level: Easy Section: 13-3 Page: 347</p><p>21. Cookies are attached to a web page before being sent to the browser. Answer: False Level: Moderate Section: 13-3 Page: 347</p><p>22. An appliance state is an example of a server-side state management technique. Answer: False Level: Moderate Section: 13-4 Page: 348</p><p>13 - 2 Chapter 13 – Advanced Web Forms with Databases</p><p>23. Server-side state management techniques should be used to keep sensitive information secure. Answer: True Level: Easy Section: 13-4 Page: 348</p><p>24. The application variable can be accessed by any code in any file in a web application. Answer: True Level: Easy Section: 13-4 Page: 348</p><p>25. The key term Application.VariableName is used to read or write to an application variable. Answer: False Level: Moderate Section: 13-4 Page: 348</p><p>26. An application variable is dimensioned like all other variables. Answer: False Level: Hard Section: 13-4 Page: 348</p><p>27. The syntax for creating a session variable is similar to that for creating an application variable. Answer: True Level: Easy Section: 13-4 Page: 349</p><p>28. All browsers share the same session variables. Answer: False Level: Easy Section: 13-4 Page: 349</p><p>29. Using a database means that no state information will be lost if all web servers are turned off for maintenance. Answer: True Level: Moderate Section: 13-4 Page: 349</p><p>30. A database can efficiently store state information for high volume web applications. Answer: True Level: Easy Section: 13-4 Page: 350</p><p>13 - 3 Chapter 13 – Advanced Web Forms with Databases</p><p>Multiple Choice Questions</p><p>31. Which is not a fundamental service identified in a three-tier architecture? a.) Association layer b.) Connection layer c.) Logical layer d.) Both a and b. e.) All of the above. </p><p>Answer: e Level: Moderate Section: 13-1 Page: 345</p><p>32. Which layer is exemplified by a web server? a.) Application b.) Association c.) Data d.) Logical e.) Presentation </p><p>Answer: a Level: Easy Section: 13-1 Page: 345</p><p>33. Which layer is exemplified by a fat client? a.) Application b.) Association c.) Data d.) Logical e.) Presentation </p><p>Answer: e Level: Moderate Section: 13-1 Page: 345</p><p>34. Which layer is exemplified by the use of ADO.NET? a.) Application b.) Association c.) Data d.) Logical e.) Presentation </p><p>Answer: c Level: Moderate Section: 13-1 Page: 345</p><p>13 - 4 Chapter 13 – Advanced Web Forms with Databases</p><p>35. How will using a middle tier typically affect the number of connections to a database? a.) Increase the number b.) Have no effect on the number c.) Decrease the number d.) It depends on the type of client. e.) It depends on the type of database.</p><p>Answer: c Level: Hard Section: 13-1 Page: 345</p><p>36. An application layer: a.) will contain business logic. b.) manage connections to the database. c.) can be distributed over many computers. d.) Both a and b. e.) All of the above. </p><p>Answer: e Level: Moderate Section: 13-1 Page: 345</p><p>37. A data layer is responsible for: a.) retrieving information from a database. b.) updating information in a database. c.) deleting information in a database. d.) Both a and b. e.) All of the above. </p><p>Answer: e Level: Easy Section: 13-1 Page: 345</p><p>38. What is the minimum number of computers in a three-tier architecture? a.) 0 b.) 1 c.) 2 d.) 3 e.) 4 or more</p><p>Answer: b Level: Easy Section: 13-1 Page: 346</p><p>39. A server farm is: a.) an example of a distributed application. b.) makes it easy to add new computers if demand increases. c.) applies only to web servers. d.) Both a and b. e.) All of the above. </p><p>Answer: d Level: Moderate Section: 13-1 Page: 346</p><p>13 - 5 Chapter 13 – Advanced Web Forms with Databases</p><p>40. Which is a valid type of state management for the creation of web pages? a.) Client side b.) Server side c.) Data side d.) Both a and b. e.) All of the above. </p><p>Answer: d Level: Easy Section: 13-2 Page: 346</p><p>41. The stateless HTTP protocol refers to web pages created: a.) on a web server. b.) without information from a database. c.) without knowledge of previous web pages. d.) before a request from a client. e.) on a client machine.</p><p>Answer: c Level: Moderate Section: 13-2 Page: 346</p><p>42. Client-side state management techniques are appropriate when using: a.) sensitive information. b.) critical applications. c.) an intranet. d.) Both a and b. e.) All of the above. </p><p>Answer: c Level: Moderate Section: 13-3 Page: 346</p><p>43. Where does the view state store information? a.) HTML source b.) Text file c.) URL d.) Both a and b. e.) All of the above. </p><p>Answer: a Level: Moderate Section: 13-3 Page: 347</p><p>44. Where does the query string store information? a.) HTML source b.) Text file c.) URL d.) Both a and b. e.) All of the above. </p><p>Answer: c Level: Moderate Section: 13-3 Page: 347</p><p>13 - 6 Chapter 13 – Advanced Web Forms with Databases</p><p>45. Where do cookies store information? a.) HTML source b.) Text file c.) URL d.) Both a and b. e.) All of the above. </p><p>Answer: b Level: Moderate Section: 13-3 Page: 347</p><p>46. Which client-side technique is specific to ASP.NET? a.) Cookies b.) Query string c.) View state d.) Both a and b. e.) All of the above. </p><p>Answer: c Level: Hard Section: 13-3 Page: 347</p><p>47. Which client-side technique can be disabled by the end-user? a.) Cookies b.) Query string c.) View state d.) Both a and b. e.) All of the above. </p><p>Answer: a Level: Moderate Section: 13-3 Page: 347</p><p>48. What symbol specifies the beginning of a query string? a.) @ b.) # c.) $ d.) % e.) ?</p><p>Answer: e Level: Easy Section: 13-3 Page: 347</p><p>49. What is the syntax for creating and using an application variable? a.) Application.VariableName = Value b.) Application.VariableName = (Value) c.) Application(VariableName) = Value d.) Application(VariableName) = (Value) e.) Application(“VariableName”) = Value</p><p>Answer: e Level: Moderate Section: 13-4 Page: 348</p><p>13 - 7 Chapter 13 – Advanced Web Forms with Databases</p><p>50. Which server-side technique is available in ASP.NET? a.) Application states b.) Session states c.) Database support d.) Both a and b. e.) All of the above. </p><p>Answer: d Level: Easy Section: 13-4 Page: 349</p><p>51. An Application variable is created: a.) when the application is first placed on a web server. b.) when the web server is first started. c.) when the first client requests a URL resource. d.) every time a client requests a URL resource. e.) every time a new client interacts with the web application.</p><p>Answer: c Level: Moderate Section: 13-4 Page: 348</p><p>52. A Session variable is created: a.) when the application is first placed on a web server. b.) when the web server is first started. c.) when the first client requests a URL resource. d.) every time a client requests a URL resource. e.) every time a new client interacts with the web application.</p><p>Answer: e Level: Moderate Section: 13-4 Page: 349</p><p>53. If there is no activity from a browser, how long will a session variable last? a.) 10 minutes b.) 20 minutes c.) 60 minutes d.) 100 minutes e.) 200 minutes</p><p>Answer: b Level: Easy Section: 13-4 Page: 349</p><p>54. Which is not a reason for using a database to store state information? a.) The capacity to store high volumes of information b.) The ability to use data mining techniques on the stored information c.) The ability to use application and session variables d.) Security from unauthorized use e.) The power to easily query for specific information</p><p>Answer: c Level: Hard Section: 13-4 Page: 350</p><p>13 - 8 Chapter 13 – Advanced Web Forms with Databases</p><p>Fill in the Blank Questions</p><p>55. Most applications can be partitioned into three logical layers: ___presentation___, application___, and ___data___ layers. Level: Easy Section: 13-1 Page: 344</p><p>56. In a three-tier system architecture an Access database represents the ___data___ layer. Level: Easy Section: 13-1 Page: 345 </p><p>57. In a three-tier system architecture a web browser represents the ___presentation___ layer. Level: Easy Section: 13-1 Page: 345</p><p>58. In a three-tier system architecture an IIS Web server represents the ___application___ layer. Level: Easy Section: 13-1 Page: 345</p><p>59. A(n) ___fat client___ refers to a user’s computer that has a substantial processing load. Level: Moderate Section: 13-1 Page: 345</p><p>60. Mobile computing devices run as a(n) ___thin client___ user layer architecture. Level: Moderate Section: 13-1 Page: 345</p><p>61. Changing business rules is easy when they are contained in modules located in the ___application___ layer. Level: Moderate Section: 13-1 Page: 345 </p><p>62. The ___application___ layer shields the end user from the details of using the database. Level: Moderate Section: 13-1 Page: 345 </p><p>63. A(n) ___server farm___ is a collection of computers that share the work of an application or data layer. Level: Moderate Section: 13-1 Page: 346</p><p>64. The protocol for creating web pages is ___stateless___ because new pages are created without information about the previous web pages. Level: Hard Section: 13-2 Page: 346</p><p>65. The technique of ___state management___ is the process of storing information over multiple web page requests. Level: Moderate Section: 13-2 Page: 346</p><p>13 - 9 Chapter 13 – Advanced Web Forms with Databases</p><p>66. Storing information about previous web pages on the ___client___ side is best done with secure, intranet applications. Level: Moderate Section: 13-2 Page: 346</p><p>67. Cookies are an example of ___client side___ state management. Level: Easy Section: 13-3 Page: 346</p><p>68. ASP.NET can save the state of a page as a part of the ___view state___ facility. Level: Moderate Section: 13-3 Page: 347 </p><p>69. The information in a(n) ___query string___ is visible in the web page’s URL. Level: Moderate Section: 13-3 Page: 347</p><p>70. Information about a web page that is stored in a text file is called a(n) ___cookie___. Level: Moderate Section: 13-3 Page: 347</p><p>71. The ___application___ state holds information for the life of a web application. Level: Moderate Section: 13-4 Page: 348</p><p>72. The first request for a URL resource generates the ___application state___. Level: Moderate Section: 13-4 Page: 348</p><p>73. The key term for creating an application variable is ___Application___. Level: Easy Section: 13-4 Page: 348</p><p>74. Each ___browser___ that requests a web application gets its own session state. Level: Moderate Section: 13-4 Page: 349</p><p>75. The key term for creating a session variable is ___Session___. Level: Easy Section: 13-4 Page: 349</p><p>76. Session variables will be lost after ___20 minutes___ inactivity. Level: Moderate Section: 13-4 Page: 349</p><p>13 - 10 Chapter 13 – Advanced Web Forms with Databases</p><p>77. Increase security is an advantage of the ___database___ server-side state management technique. Level: Moderate Section: 13-4 Page: 350</p><p>78. Application layers are ___worse__ than data layers at storing large volumes of state information. Level: Moderate Section: 13-4 Page: 350</p><p>79. State information store in a database is considered ___persistent___ because it is less prone to server crashes than web servers. Level: Hard Section: 13-4 Page: 350</p><p>Essay Questions</p><p>80. Identify and describe the layers of a three-tier architecture.</p><p>The three-tier architecture breaks the logic of an application into three modules, called layers. These layers are Presentation, Application, and Data. Physically these three layers can reside on the same computer or three separate computers. The design of the architecture is a conceptual division of functionality.</p><p>The Presentation layer is the part of the application that the end user sees and interacts with. It hides the details of the other layers and makes the application easy to use. This layer can be a Windows form processing data locally on a client’s computer (fat client) or an internet browser with displaying an ASP.NET Web form (thin client).</p><p>The Application layer has two main functions: to process business rules and interact with the data layer. This layer typically is a web server that delivers web pages to a browser, but it can also be an application server on an intranet that communicates to with the Windows form presentation layer. The advantage of the application layer is that changes in business rules (a new state tax rate) require changes on a few application servers, rather than the thousands of computers that hold the presentation layer.</p><p>The Data layer is where all of the information vital to the business is stored. Typically this is done is a database, but flat files (text files) can be used as well. It is best to use databases because they are designed to accurately modify (add, delete, edit) and retrieve (query) data. The fact that only the application layer interacts with the database increases the security of the information stored in the data layer.</p><p>81. What is State Management? Describe and give examples of the two types of State Management techniques.</p><p>State management is the storage of information about web pages each time a user accesses a web server. This is important because one web server is designed to serve many clients and the HTTP protocol does not require that the state of each web page be remembered. When a server farm of web servers is used, it is possible that each request to the web site will go to a different computer </p><p>13 - 11 Chapter 13 – Advanced Web Forms with Databases making it impossible for one web server to know what web page the other web server just sent out.</p><p>One method to store the state of a web page is to embed the information on the Client (end user’s) machine in the form of a View State, Query String, or Cookie. The View State is a feature provided by ASP.NET which will store information about the state of the web page in the HTML source. The Query String is information stored in the URL address (identified with a ?). A Cookie is a text file stored on the client’s computer. Because the information store with these techniques is accessible by the end user, client-side techniques should not be used to store vital or sensitive information.</p><p>The other method to store the state of a web page is to store the information on a server. This can be either a web server in the form of Application or Session variables, or on a database server. Both methods are better at keeping data secure.</p><p>13 - 12</p>
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