Freetutes.com

VB6 beginners tutorial - Learn VB6

Advanced VB6 tutorial - Learn Advanced VB6

VB .NET - Learn Visual Basic .NET

Systems Analysis - System analysis and Design tutorial for Software Engineering


You are here: Visual Basic > Advanced VB6 tutorial > Chapter 17

Creating a Simple ASP Page

Listing 17.1 illustrates a simple ASP file that you could create in a folder on your Web server.

LISTING 17.1
AN ASP FILE

<HTML>
<BODY>
<B>ASP-generated section follows:</B><BR>
<%
   ‘GET THE CURRENT TIME AS A FORMATTED STRING
   Dim sTime
   sTime = Now
   ‘OUTPUT TIME INFORMATION IN HTML TEXT
   Response.WritesTime
   Response.Write "<BR>"
   ‘INITIALIZE ASP CLASS OBJECTS TO GET
   ‘INFORMATION ABOUT THE E: DRIVE
   Dim objFileSys, objDrives, objDrive
   On error Resume Next
   Set objFileSys = _
   Server.CreateObject("Scripting.FileSystemObject")
   Set objDrives = objFileSys.Drives
   Set objDrive = objDrives("F")
   ‘OUTPUT VOLUME INFORMATION IN HTML TEXT
   Response.Write "The Volume Label In Drive <B>"
   Response.Write objDrive.DriveLetter
   Response.Write "</B> is <B>"
   Response.Write objDrive.VolumeName
   Response.Write "</B><BR>"
   ’CLEAN UP OBJECTS
   Set objDrives = Nothing
   Set objFileSys = Nothing
   Set objDrive = Nothing
%>
<B>End of ASP-generated section</B>
</BODY>
</HTML>

Note the following features of an ASP file, as illustrated in Listing 17.1:

  • Besides the enhanced ASP features, an ASP file also contains normal HTML script. In the preceding listing example, note the beginning and ending <BODY> and <HTML> tags, as well as the HTML text with bold formatting (<B>…</B>) tags toward the beginning and end of the file. Any normal HTML script outside the ASP delimiters (as discussed in the next point) will pass through to the end user’s browser as-is.

  • The ASP-specific portions of the file are delimited by the <%…%> pair of tags. Everything between this pair of tags is interpreted by ASP and then gets stripped out before it reaches the end-user’s browser.

  • The ASP portion of the file is written in VBScript, which is basically a subset of VB. You should recognize the VB syntax of the ASP code in the example.

  • Note the use of CreateObject, which allows the VBScript code to instantiate COM objects from classes registered on the Web server machine. Chapter 10, "Instantiating and Invoking a COM Component," discusses programming with existing COM components in more detail. The capability to instantiate components inside an ASP script is the key to launching WebClass applications, as discussed in the following sections.

  • ASP provides several built-in object classes not found in the VB environment. The example uses two of these object classes, the Response object and the Scripting.FileSystemObject class.

  • In the ASP section of the file, you use the Response object’s Write method to generate HTML code that will be embedded in the final HTML file that the server sends to the browser. All arguments to the Response object are string literals or variables, as shown in the example.

The sample ASP file of Listing 17.1 would produce an end result on client browsers that would look like Figure 17.1.

How the ASP file appears on a browser
FIGURE 17.1 How the ASP file appears on a browser

If end users chose the View Source option on the browser to see the HTML code behind the page, they would see something very close to Listing 17.2

LISTING 17.2
INTERNET INFORMATION SERVER GENERATED THIS PURE HTML CODE FROM THE ASP FILE AND SENT IT TO THE BROWSER

<HTML>
<BODY>
<B>ASP-generated section follows:</B><BR>
11/28/98 12:08:16 AM<BR>The Volume Label In Drive <B>F</B> is <B>VSE600ENU2</B><BR>
<B>End of ASP-generated section</B>
</BODY>
</HTML>

Notice that Listing 17.2 shows no trace of the ASP code. Instead, it shows only the basic HTML code that was in the file outside of the ASP section and the output of the Response.Write method from the ASP section. The Web server stripped out all the ASP code before transmitting the page to the browser.


  

<< Previous | Contents | Next >>

Home | About Us | Privacy Policy | Contact Us

Copyright © Freetutes.com | All Rights Reserved