HTTP HEAD Request to Determine if Resource Exists and Size

This example sends an HTTP HEAD request to determine if a resource exists on an HTTP server. If so, it reports the size (in bytes) of the resource. The HTTP HEAD request can be used to query about a resource without downloading it.

Chilkat.Http http = new Chilkat.Http();
bool unlocked = http.UnlockComponent("Any string begins 30-day trial");
if (!unlocked)
{
    MessageBox.Show("Failed to unlock HTTP component");
    return;
}

Chilkat.HttpRequest req = new Chilkat.HttpRequest();
req.UseHead();
req.Path = "/download/ChilkatDotNet.msi";

bool ssl = false;   // Set this to true to use HTTPS
Chilkat.HttpResponse resp = http.SynchronousRequest("www.chilkatsoft.com",80,false,req);
if (resp == null) 
{
    MessageBox.Show(http.LastErrorText);
    return;
    }
    
// Does the resource exist?
if (resp.StatusCode == 200)
{
    // Display a message with the size of the resource in bytes.
    MessageBox.Show("The web resource exists and is " + 
	Convert.ToString(resp.ContentLength) + " bytes");
    }
else
{
    // Show the full response header...
    MessageBox.Show(resp.Header);
    }		    

Important: The download for this example does not contain the ChilkatDotNet.dll which
must be downloaded and installed separately at http://www.chilkatsoft.com/downloads.asp.
Once installed, add a reference to the DLL in the project by following the instructions at
http://www.example-code.com/vbdotnet/step2.asp