The Application Object
Unlike the Session object, the Application object stores application information shared among all users of a site. Application information lasts as long as the web server is running.
| Application Object: Methods | |
| Application.Lock | Locks the variables in an application while their values are being changed. |
| Application.Unlock | Unlocks the variables in an application. |
| Application Object: Collections | |
| Application.Contents | Contains items added to the Application object using script. |
| Application.StaticObjects | Contains items added to the Application object using the HTML |
| Application Object: Events | |
| Application.OnStart | Specifies an event to occur when the server starts an application. |
| Application.OnEnd | Specifies an event to occur when an application ends. |
Using Application Variables
Application variables are created and accessed just like Session variables. The only difference is the statement-Application(“variable”)-and the fact that application variables can be accessed by all sessions (users).
<% Application(“Visits”)=Application(“Visits”)+1 %>
Counter: <%=Application(“Visits”)%> visits
|
Each time you refresh a page with the above code, the counter increases by 1. It will continue to increase as other users access the page.
The Server Object
The Server object creates objects on and provides access to the web server. For example, you can use the Server object to create ActiveX objects, create recordsets (when connected to a database), or access information such as the physical path to items in a directory on the server.
| Server Object: Methods | |
| Server.CreateObject | Creates an instance of an object, such as an ActiveX object or a recordset. |
| Server.Execute | Accesses one ASP page from another (includes the contents of the page in the calling page). |
| Server.GetLastError() | Creates an instance of the ASPError object, which describes the error that occurred. |
| Server.HTMLEncode | Forces a client to process HTML code as plain text. |
| Server.MapPath | Returns the physical path of a file on the server. |
| Server.Transfer | Transfers information created on one page to another page. |
| Server.URLEncode | Encodes a string as a URL so it can be passed from one page to another. |
| Server Object: Properties | |
| Server.ScriptTimeout | Specifies the number of seconds a server will process a script before timing out. |
Setting Script Timeout
You can set the timeout property for a lengthy script to prevent the server from timing out before processing is complete:
| <% Server.ScriptTimeout=300 %> |
Note: The timeout setting for a script cannot exceed the timeout setting for the server.
Displaying HTML Code as Text
You may occasionally need to display symbols that are ordinarily interpreted as HTML code-for example, the angle brackets (<>). To do so, you can use the Server.HTMLEncode statement:
| <% Response.Write(“Use the paragraph tag ” & Server.HTMLEncode(“ “) & ” to format paragraph text.”) %> |
Encoding a URL
Because a browser can misinterpret spaces and special characters in a URL (as when, for example, a query string is passed), you should use the Server.URLEncode statement to encode a URL being passed from one page to another:
| <% Dim FavoriteURL FavoriteURL=Request.Form(“txtFavURL”) %> Click the link below to visit your favorite URL: ><%=FavoriteURL%> |
In the code above, a user’s entry for a favorite URL is requested from a from on another page and displayed as a hyperlink on the current page. While the text for the hyperlink appears as the user entered it, the actual hyperlink is encoded to be interpreted correctly by the browser.
Mapping Server File Paths
You use the Server.MapPath statement to return the physical path for a file on the server. To return the path of the server’s root directory, include a slash (/) or a backslash (\):
| <%Response.Write(Server.MapPath(“/”))%> <%Response.Write(Server.MapPath(“SendData.asp”))%> |
Creating Server Objects
Much of the power of dynamic content can be found in its ability to interact with a database. From any Internet connection, users can browse, sort, update and delete records using a simple but flexible interface that is, on the developer’s side, both secure and easy to code. You use the Server.CreateObject statement to create the objects necessary for interacting with a database. The following code creates a Connection object to connect to a database:
| <% Dim cnn Set cnn=Server.CreateObject(“ADODB.Connection”) cnn.ConnectionTimeout=60 cnn.Open “DSN=TestDB” cnn.Close Set cnn=Nothing %> |
You can also create a Recordset object:
| <% Dim cnn Dim rs Set cnn=Server.CreateObject(“ADODB.Connection”) cnn.ConnectionTimeout=60 cnn.Open “DSN=TestDB” Set rs=Server.CreateObject(“ADODB.Recordset”) rs.Open “Select * From tblTest”,cnn cnn.Close Set cnn=Nothing %> |
