HTTP Modules are assemblies which can be called during every http request.
This comes in very handy when there is a need to intercept every request that comes into the Web application.
This is basically a simple class that is derived from IHttpModule
Here is the sample code. This will be compiled to a DLL file.
public class MyClass : IHttpModule
{/// <summary>
/// This is the disposing function.
/// </summary>
void IHttpModule.Dispose()
{
}
/// <summary>
/// This is the
initialization function./// </summary>
/// <param name="context">This is the httpApplication context.</param>
void IHttpModule.Init(HttpApplication httpApp)
{
httpApp.BeginRequest += new EventHandler(context_BeginRequest);
}
/// <summary>
/// This is where the Begin Request Action is taking place.
/// </summary>
/// <param name="sender"></param>
/// <param name="e"></param>
void context_BeginRequest(object sender, EventArgs e)
{
HttpApplication httpApp = (HttpApplication)sender;
RequestManipulation(httpApp);
}
/// <summary>
/// This is the core
function which tries to alter the request./// </summary>
private void RequestManipulation(HttpApplication httpApp)
{
AlterNameValueCollection(httpApp);
}
/// <summary>
/// Writes details of
the Form NameValueCollection in the REQUEST object./// </summary>
/// <param name="httpApp">This is the input HttpApplication context from which the request header details will be written out.</param>
private void AlterNameValueCollection(HttpApplication httpApp)
{
NameValueCollection postInfo = httpApp.Request.Form;
System.Reflection.PropertyInfo prop = httpApp.Request.Form.GetType().GetProperty("IsReadOnly", System.Reflection.BindingFlags.Instance | System.Reflection.BindingFlags.NonPublic);
// Set the property false (writable)
prop.SetValue(httpApp.Request.Form, false, null);
foreach (String eachKey in postInfo.AllKeys)
{
string towrite = string.Format("Key : {0} - Value : {1}", eachKey, httpApp.Request.Form[eachKey]);
Helper.WriteinFile(towrite);
if (eachKey == "AuthorName")
{
Helper.WriteinFile("Before Changing AuthorName value....");
string oldValue = httpApp.Request.Form[eachKey].ToString();
httpApp.Request.Form[eachKey] = "MyClass Success. The old value '" + oldValue + "' was modified by the MyClass dll." ;
Helper.WriteinFile("Just now changed the AuthorName value.");
}
}
}
}
This DLL will be loaded into memory by using the following entries in the "Web.Config" file.
<system.webServer>
<modules><add name="MyClass" type="MyNamespace.MyClass, MyClass, Version=1.0.0.0, Culture=neutral, PublicKeyToken=77ced88f9fdf21cb" preCondition="managedHandler,runtimeVersionv4.0" />
</modules>
</system.webServer>
Hope this blog helps.
Happy coding !
Cheers
Adam
