1 00:00:00,005 --> 00:00:03,004 - [Instructor] As login use case is an included use case 2 00:00:03,004 --> 00:00:06,005 on which the other functionalities depend upon, 3 00:00:06,005 --> 00:00:09,001 let us first design login functionality. 4 00:00:09,001 --> 00:00:12,007 To start with, let us take a look at its UI mockup. 5 00:00:12,007 --> 00:00:15,004 This one is simple, we start off with a page 6 00:00:15,004 --> 00:00:17,003 in which there are just these links, 7 00:00:17,003 --> 00:00:19,004 with one of them being login. 8 00:00:19,004 --> 00:00:22,003 Once we choose that, it takes us to login page 9 00:00:22,003 --> 00:00:25,002 where we enter username and password, 10 00:00:25,002 --> 00:00:29,004 and then once the login is successful, it shows other links, 11 00:00:29,004 --> 00:00:33,009 such as record meal, view diet log, et cetera. 12 00:00:33,009 --> 00:00:37,004 The sequence diagram for this flow will look like this. 13 00:00:37,004 --> 00:00:40,004 User chooses login option from Index, 14 00:00:40,004 --> 00:00:43,003 which forwards the request to LoginController, 15 00:00:43,003 --> 00:00:48,001 which in turn forwards it to LoginInput JSP. 16 00:00:48,001 --> 00:00:51,008 LoginInput JSP takes username and password from user 17 00:00:51,008 --> 00:00:54,005 and forwards them to LoginValidator, 18 00:00:54,005 --> 00:00:58,007 which then reaches out to Dao to connect with Red30 DB, 19 00:00:58,007 --> 00:01:01,001 that has user data for validation. 20 00:01:01,001 --> 00:01:04,003 If Dao finds that user credentials match 21 00:01:04,003 --> 00:01:07,006 with the ones in database, it creates User object, 22 00:01:07,006 --> 00:01:10,005 which will now be used for other use cases. 23 00:01:10,005 --> 00:01:13,006 It sends the validation status to LoginResponse, 24 00:01:13,006 --> 00:01:16,000 which displays a message about whether login 25 00:01:16,000 --> 00:01:17,007 was successful or not. 26 00:01:17,007 --> 00:01:20,008 As you can see, the entire flow is in a loop 27 00:01:20,008 --> 00:01:24,003 indicating that system will ask user to login 28 00:01:24,003 --> 00:01:25,009 until successful. 29 00:01:25,009 --> 00:01:27,004 When we think about login, 30 00:01:27,004 --> 00:01:30,005 we also need to think about the flow for logout. 31 00:01:30,005 --> 00:01:33,008 In larger applications, there may be several activities, 32 00:01:33,008 --> 00:01:36,002 such as logging the date and time 33 00:01:36,002 --> 00:01:38,007 when the user signed in or signed out, 34 00:01:38,007 --> 00:01:41,003 closing user-specific resources, 35 00:01:41,003 --> 00:01:44,002 and updating other user-related data. 36 00:01:44,002 --> 00:01:46,006 In this case, all we are doing 37 00:01:46,006 --> 00:01:50,004 when the user chooses logout option from Index JSP, 38 00:01:50,004 --> 00:01:54,001 the control goes to a servlet named Logout, 39 00:01:54,001 --> 00:01:57,002 which gets the session object from request object, 40 00:01:57,002 --> 00:01:59,006 and then invalidates the session. 41 00:01:59,006 --> 00:02:02,007 Putting all the objects identified above gives 42 00:02:02,007 --> 00:02:05,003 us this class diagram. 43 00:02:05,003 --> 00:02:08,000 I have created another package, login, 44 00:02:08,000 --> 00:02:11,000 inside com.hplussport.red30 package 45 00:02:11,000 --> 00:02:12,006 that has three servlets, 46 00:02:12,006 --> 00:02:16,007 LoginController, LoginValidator, and LogOut. 47 00:02:16,007 --> 00:02:18,007 There is a new method in Dao 48 00:02:18,007 --> 00:02:21,005 to validate the user's name and password, 49 00:02:21,005 --> 00:02:23,008 and if the credentials are correct, 50 00:02:23,008 --> 00:02:28,002 then Dao creates a new user instance, which is a bean. 51 00:02:28,002 --> 00:02:30,001 From data model point of view, 52 00:02:30,001 --> 00:02:33,003 we need to add one table to our Red30 DB, 53 00:02:33,003 --> 00:02:35,001 which is the user table. 54 00:02:35,001 --> 00:02:38,000 We have just two fields in the table as of now, 55 00:02:38,000 --> 00:02:40,004 username and password. 56 00:02:40,004 --> 00:02:42,001 In more complex scenarios, 57 00:02:42,001 --> 00:02:44,001 you would need many more parameters, 58 00:02:44,001 --> 00:02:47,001 such as role related to access privileges, 59 00:02:47,001 --> 00:02:51,004 user preferences, record of logins and logouts, and so on. 60 00:02:51,004 --> 00:02:53,004 Let us look at the code now. 61 00:02:53,004 --> 00:02:57,004 Earlier, our header JSP had just one set of links 62 00:02:57,004 --> 00:03:00,001 for non-registered users. 63 00:03:00,001 --> 00:03:03,009 But once the user logs in, then the header has to change 64 00:03:03,009 --> 00:03:06,008 to display links for new use cases. 65 00:03:06,008 --> 00:03:09,006 I have enabled this switch in header JSP 66 00:03:09,006 --> 00:03:12,003 by splitting the JSP into two parts. 67 00:03:12,003 --> 00:03:16,005 In line five, I check if session attribute user is null. 68 00:03:16,005 --> 00:03:19,005 If it is, then I display the old set of links 69 00:03:19,005 --> 00:03:22,005 from line 19 to 22. 70 00:03:22,005 --> 00:03:26,002 If it is not null, then I display another set of links 71 00:03:26,002 --> 00:03:29,005 in lines from 42 to 48. 72 00:03:29,005 --> 00:03:33,005 So, once the user logs in, the reference in line 22 73 00:03:33,005 --> 00:03:38,006 takes us to LoginController, which is inside login package. 74 00:03:38,006 --> 00:03:44,000 LoginController forwards the request to login input JSP. 75 00:03:44,000 --> 00:03:48,008 This has a form in line 13 that has two input boxes 76 00:03:48,008 --> 00:03:51,008 in line 17 and line 21. 77 00:03:51,008 --> 00:03:54,003 These are for username and password. 78 00:03:54,003 --> 00:03:56,001 Once the form is submitted, 79 00:03:56,001 --> 00:03:58,002 the action takes us to validate, 80 00:03:58,002 --> 00:04:01,005 which is the LoginValidator class. 81 00:04:01,005 --> 00:04:05,001 This is where the Dao comes in at line 30, 82 00:04:05,001 --> 00:04:07,005 validates the username and password, 83 00:04:07,005 --> 00:04:10,002 and creates user instance that gets saved 84 00:04:10,002 --> 00:04:13,004 as session variable in line 31. 85 00:04:13,004 --> 00:04:17,008 Finally, the request is forwarded to login response JSP, 86 00:04:17,008 --> 00:04:22,005 which if login was unsuccessful and user object is null, 87 00:04:22,005 --> 00:04:25,002 displays the message in line 17, 88 00:04:25,002 --> 00:04:27,005 or else if it was successful, 89 00:04:27,005 --> 00:04:30,005 the welcome message in line 23. 90 00:04:30,005 --> 00:04:33,009 I have already created a table in Red30 DB, 91 00:04:33,009 --> 00:04:37,005 which we can look at through MySQL Workbench. 92 00:04:37,005 --> 00:04:40,006 As you can see here, I have added two records 93 00:04:40,006 --> 00:04:42,009 with username and password. 94 00:04:42,009 --> 00:04:45,000 Now, let us run our code. 95 00:04:45,000 --> 00:04:47,006 For that, I go back to Eclipse, 96 00:04:47,006 --> 00:04:52,005 and, as usual, Run As, Run on Server, 97 00:04:52,005 --> 00:04:55,009 and wait for initial data load. 98 00:04:55,009 --> 00:04:59,006 Now the application is up, so I go into login 99 00:04:59,006 --> 00:05:03,001 and enter the username and password based on the data 100 00:05:03,001 --> 00:05:07,008 that you just saw, and the login is successful. 101 00:05:07,008 --> 00:05:12,001 You can see new links that are meant for registered users. 102 00:05:12,001 --> 00:05:15,001 If I log out, then I come back to the page 103 00:05:15,001 --> 00:05:17,005 for unregistered users. 104 00:05:17,005 --> 00:05:20,005 At this point, we don't want to publish these changes 105 00:05:20,005 --> 00:05:23,008 to our production server because our real use cases 106 00:05:23,008 --> 00:05:28,000 for recording meals and viewing diet logs are not ready yet.