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A Sample Application of the Browser Capabilities Component

This section presents a possible application of the Browser Capabilities component. The purpose of this example is not only to show how to use the component, but also to show its limitations.

In the Active Server Page shown in Listing 18.1, the Browser Capabilities component is used to detect whether a browser can use frames. If the browser can use frames, a framed version of the page is displayed. If the browser can't use frames, the user is warned that he or she must have a frames-compliant browser to visit the Web site.

<%
Set MyBrow=Server.CreateObject("MSWC.BrowserType")
IF MyBrow.Frames THEN
%>
<HTML>
<HEAD><TITLE> Framed Page </TITLE></HEAD>
<FRAMESET COLS="100,*">
<FRAME SRC="menu.asp">
<FRAME SRC="body.asp">
</FRAMESET>
</HTML>
<% ELSE %>
<HTML>
<HEAD><TITLE> Frameless Page </TITLE></HEAD>
<BODY>

We have detected that your browser is incapable of using frames. You are using a <%=MyBrow.browser%> browser (version <%=MyBrow.version %>).
To download a more recent browser, please visit:
<P> <A HREF="http://www.microsoft.com">Microsoft</A>
<P> OR
<P> <A HREF="http://www.netscape.com">Netscape</A>
</BODY>
</HTML>
<% END IF %>

This Active Server Page conditionally displays two other pages. If the Browser Capabilities component detects that a user's browser can interpret the frame tags, the first page is displayed. This page displays two frames. Otherwise, the second page is displayed. Notice how the Browser Capabilities component is also used to report the name and version of the browser being used.

This example not only illustrates how the Browser Capabilities component can be used, but also why the component normally should not be used for this purpose. It illustrates a serious problem with the Browser Capabilities component.

The problem with this Active Server Page is that it will always display the second page when it doesn't recognize a browser. In other words, even if a browser can support frames, the second page will be displayed when the Browser Capabilities component doesn't recognize it. For example, as of the printing date of this book, the current version of the browscap.ini file didn't recognize the newest version of the Netscape browser. Therefore, even though this browser can use frames, the second page is displayed.

The major shortcoming of the Browser Capabilities component is that it must depend on the information placed by Microsoft or you in the browscap.ini file. The speed at which new technologies and new browsers are introduced on the Internet undermines its usefulness.

When possible, it's much better to use HTML itself to display different content, depending on the capabilities of a browser. For example, a better way to detect whether a browser can use frames is by using the <NOFRAMES> HTML tag, as described in Chapter 7, "Advanced HTML" The advantage of this approach is that it should continue to work with new browsers.

Summary

In this chapter, you learned how to integrate ActiveX components into your Active Server Pages. You learned how to create an instance of a component with page, session, and application scope, and how to use the Browser Capabilities component. Finally, an example of an Active Server Page using the Browser Capabilities component was provided. This example also demonstrated a significant limitation of this component.