application|session| Objects III, Global.asa
ASP's application and session objects embody features that are not in the other ASP's built-in objects-events. Each visitor accesses the server and triggers a OnStart event (the first visitor triggers both the application and session OnStart events, but application is preceded). A OnEnd event is triggered at the end of each visitor's session (the OnEnd event of the application and session is triggered at the end of the last guest conversation, but preceded by application).
OnStart and OnEnd These two events are commonly used in virtual communities to count online numbers, modify users ' online offline status, and so on. To define both events, you need to write the code in the Global.asa file and place the file in the root directory of the site (by default, \inetpub\wwwroot\). In addition, application and session objects specify other ASP built-in objects (Response, Request, Server, session ...) In addition to application objects in the OnEnd event. ) can not be used. Here is an example of how to use these two events with a virtual Community statistics online number.
File Description:
Global.asa is located in the D:\Inetpub\wwwroot\ directory
Default.asp is located in the D:\Inetpub\wwwroot\ directory, the virtual Community login page
Login.asp is located in the D:\Inetpub\wwwroot\ directory, used to detect user input username and password
Index.asp is located in the D:\Inetpub\wwwroot\ directory, the virtual community home
Bbs.mdb is located in the D:\Inetpub\wwwroot\ directory, the database where user information is stored
Database (ACCESS) Structure:
===bbs table = = =
ID user ID, long integer
Name username, text type
Code password, text type
Online status, yes/No
===global.asa===
<script language= "VBScript" runat= "Server"
Sub Application_OnStart
Application ("online") =0
End Sub
Sub Application_OnEnd
nd Sub
Sub Session_OnStart
End Sub
Sub Session_OnEnd
If Session.Contents ("pass") then ' to determine whether to be a logged-on user's Session_OnEnd
Application.Lock
Application ("Online") =application ("online")-1
Application.UnLock
End If
End Sub
</script>
==============
===login.asp===
... ' Password authentication, connect the database, detect the user entered the user name and password is correct
If password verification through then
Session ("name") =rs ("name")
Session ("id") =rs ("id")
Session ("Pass") =true
Else
Rs.close
Conn.close
Response.Write "Bad password! "
Response.End
End If
Application.Lock
Application ("Online") =application ("online") +1
Conn. Execute ("Update BBS set online=1 where id=" &session ("id")) ' sets the user's state to online
Application.UnLock
Rs.close
Conn.close
Response.Redirect "index.asp" ' Initialize data and jump to the home page of the community
===========
In this case, the application ("online") variable is used to record the number of online people who have logged in to the community, because once a user accesses the server regardless of whether the user is logged on, the OnStart event is generated, so Applicaiton (" Online ") plus one. Because whether or not the end of a logged-on user's session generates a OnEnd event (if a visitor accesses the server but does not log in to the community, and a OnEnd event occurs after his session ends), the Session_ The OnEnd event uses a sentence if statement to determine whether the logged in user's OnEnd event, if it is the number of people online minus one.
This is just a simple example of the number of people online, for a complete virtual community, it is not enough to count the number of users online, in this case there is a online field in the database to record the user's status, the user logged in, In the Login.asp will be online set to 1, but the user offline and did not set the online to 0, to improve it, it is necessary to modify the Session_OnEnd event, the event in the online set to 0.
===global. sas===
<script language= "VBScript" runat= "Server"
Sub Application_OnStart
Application ("online") =0
Set Application ("conn") =server.createobject ("ADODB. Connection ")
Application ("DB") =server.mappath ("\bbs.mdb") ' It is best to use absolute path \bbs.mdb here, described in detail below
End Sub
Sub Application_OnEnd
Set Application ("conn") =nothing
End Sub
Sub Session_OnStart
End Sub
Sub Session_OnEnd
If Session.Contents ("pass") then ' to determine whether to be a logged-on user's Session_OnEnd
Application ("Con"). Open = "Driver={microsoft Access driver (*.mdb)};d bq=" &application ("db")
Application.Lock
Application ("Online") =application ("online")-1
Application ("Con"). Execute ("Update friends set online=0 where id=" &session.contents ("id"))
Application.UnLock
Application ("Con"). Close
End If
End Sub
</script>
==============
At this point, the complete code is complete. Because the server object cannot be used in the application and session OnEnd events, the connection to the database and the physical address of the database on the server (d:\inetpub\wwwroot\ Bbs.mdb) is stored in the application variable and is processed in the Application_OnStart event in advance. Similarly, it is not possible to replace session.contents ("pass") with the session ("pass") in the Session_OnEnd event (with a detailed description below).
Four, two points worth noticing in the example of this article
The session.contents in the ⒈onend incident
Friends who have just started to contact Global.asa often take the Session_OnEnd event
