The Response Object
One of the most important objects in ASP is the Response object. It is
the object which communicates between the server and the output which is
sent to the client. To write an ASP page, all you need to do is write a
standard HTML page, putting in the Active Server Pages script where
needed. Active Server Pages script is denoted by the text between
<%'s and %>'s.
To send ASP to the client, you need to use the Response object. The
method of the Response object which sends data to the client is the Write
method. For example, if you write an HTML page which looks like:
<%@ LANGUAGE="VBSCRIPT" %>
<HTML>
<BODY>
<% Response.Write("Hello, World!") %>
</BODY>
</HTML>
if a user views the page with a standard browser, they will see the text,
"Hello, World!" on the screen. It's as if you had just written an HTML
page with the words "Hello, World!" where the <%'s the text between
and the %>'s were. Of course, unlike an HTML page which is sent
directly to the client, this page has passed through the server's ASP.DLL,
parsing it so that instead of the client seeing <%
Response.Write("Hello, World!") %>, the client merely sees
"Hello, World!" Even if the user goes to View Source in their browser,
they will only see the "Hello, World!" This is because the client is
never sent the preprocessed ASP script.
You can inherently invoke the Response.Write method by using
the equals (=) sign. Here is an example, which happens to produce the
exact same output as above:
<%@ LANGUAGE="VBSCRIPT" %>
<HTML>
<BODY>
<%="Hello, World!" %>
</BODY>
</HTML>
As you notice, we just got rid of the Response.Write( ... ), but left the
stuff in between. The = simulates Response.Write.
There are also a few other neat properties in the Response object. One is
Expires, which sets how soon your page expires. Many modern browsers
cache pages for quicker downloading times. You can use ASP to set how
often the browser checks to see if it needs to redownload the page. You
set it in terms on minutes. If you want to browser not to cache the page,
you can set Response.Expires = 0. Let's look at an example
where we set the page to expire in 10 minutes.
<%@ LANGUAGE="VBSCRIPT" %>
<%
Response.Expires = 10
%>
<HTML>
<BODY>
This page will expire in 10 minutes
</BODY>
</HTML>
Pretty neat, eh? Another neat property of the Response object is the
Buffer property, which takes either a true or false value. If buffer is
set to true, the server processes the entire ASP script before sending
any of the file to the client. If buffering is set to
false (which it is by default), the server will send data to the client as
it processes it. Below is an example of setting buffering to true:
<%@ LANGUAGE="VBSCRIPT" %>
<%
Response.Buffer = true
%>
<HTML>
<BODY>
This page's output to the client was
buffered
</BODY>
</HTML>
