Beginning Web Development, Silverlight, and ASP.NET AJAX

66
CHAPTER 3 ■ WEB FORMS WITH ASP.NET
The Page Object
When you are running an ASP.NET application, you have access to the Page object via the
Page class. You can use this access to get valuable information such as the session, the
cache, the HTTP request, and the HTTP response (which we looked at briefly earlier in
the chapter), among others. Let’s take a look at some of these.
The Request Object
The Request object contains the values associated with the HTTP request that the browser
issued to the server to invoke your page. Its most common use is to interrogate the request
parameters. You’ve seen many URLs that look like this:
http://server/page.aspxparam=value&param=value
When ASP.NET sees a call like this, it creates an array of name/value pairs that you
can access from your code. So, for example, to test for a parameter called Test1 and pass
it to a string in your code, you would have C# that looks like this:
if (String.IsNullOrEmpty(Request.Params["test1"])){
strTest1 = Request.Params["test1"];
}
else
{
strTest = String.Empty;
}
You should always check to see if the parameter is present (non-null entry in the
array) before you load it into an internal data store, such as strTest1 in the preceding
case.
You should also sanitize all input parameters after loading them to avoid security
holes through events such as SQL injections.
The Request object supports much more than managing the parameters, including
cookies and certificates. See http://msdn2.microsoft.com/en-us/library/system.web.
httprequest(vs.80).aspx for more information.
The Response Object
As you can imagine, if you can handle requests, you can also handle responses. This is
done using the Response object, which can be used to write new output to the response
buffer or to redirect the user to another page or site.