I have two production websites that have similar content. One of these websites needs to be indexed by search engines and the other shouldn't. Is there a way of adding content to the response given to the client using the HttpModule?
In my case, I need the HttpModule to add to the response sent to the when the module is active on that particular web.
You'd probably want to handle the PreRequestHandlerExecute event of the application as it is run just before the IHttpHandler processes the page itself:
public class NoIndexHttpModule : IHttpModule
{
public void Dispose() { }
public void Init(HttpApplication context)
{
context.PreRequestHandlerExecute += AttachNoIndexMeta;
}
private void AttachNoIndexMeta(object sender, EventArgs e)
{
var page = HttpContext.Current.CurrentHandler as Page;
if (page != null && page.Header != null)
{
page.Header.Controls.Add(new LiteralControl("<meta name=\"robots\" value=\"noindex, follow\" />"));
}
}
}
The other way of doing it, is to create your own Stream implementation and apply it through Response.Filters, but that's certainly trickier.
Related
we are using HttpModule for switching aspx pages..
But if large number of client try to hit same time then people get wrong page on screen... I am not sure if something wrong in my code due to Server.TransferRequest.
Can any one give any suggestion?
public class SwitchMasterModule : IHttpModule, IRequiresSessionState
{
public void Init(HttpApplication context)
{
context.BeginRequest += Context_BeginRequest;
}
void Context_BeginRequest(object sender, EventArgs e)
{
var AppId = SiteSettings.ApplicationId().ToString();
if (HttpContext.Current.Request.CurrentExecutionFilePath.Equals("/default.aspx", StringComparison.InvariantCultureIgnoreCase))
{
HttpContext.Current.Server.TransferRequest(string.Format("~/Templates/{0}/default.aspx", AppId), true);
}
}
}
Moved from comment to answer.
It might be that SiteSettings.ApplicationId() returns incorrect value.
I don't know what the origin of the SiteSettings class is, but if it's not absolutely thread-safe, you could easily wind up with one user accessing the ApplicationId value appropriate for another user.
I'm using an HttpModule to try and redirect users to the login page if they're not authenticated, but for some reason it's just endlessly redirecting the page without landing anywhere.
Here's the module:
using System;
using System.Web;
using System.Web.Security;
public class AuthenticationModule : IHttpModule
{
public AuthenticationModule()
{
}
public string ModuleName
{
get
{
return "AuthenticationModule";
}
}
public void Init(HttpApplication app)
{
app.BeginRequest += (new EventHandler(Application_BeginRequest));
}
private void Application_BeginRequest(object source, EventArgs e)
{
HttpApplication app = (HttpApplication)source;
HttpContext context = app.Context;
HttpRequest request = context.Request;
HttpResponse response = context.Response;
if (!request.IsAuthenticated && !request.RawUrl.Contains(FormsAuthentication.LoginUrl))
{
FormsAuthentication.RedirectToLoginPage();
}
}
public void Dispose() { }
}
I don't recall having ever worked with HttpModules before, so I'm not sure what's not working.
How can I fix this?
request.RawUrl is the URL I entered into the browser. Your check request.RawUrl.Contains(FormsAuthentication.LoginUrl) is case sensitive.
Additionally there are no checks for ressources. So each request for images, css files etc. will redirect to login page. You need to check if authentication is required for the ressource being called.
Edit (hit the save button to early)
Additionally I would do it on AuthenticateRequest
Currently my product page URL is like
http://www.localhost:80/products/default.aspx?code=productCode
I want to access product page with
http://www.localhost:80/productCode
I have used HTTP module for this.
public class UrlRewritingModule : IHttpModule
{
public void Dispose()
{
}
public void Init(HttpApplication context)
{
context.PreRequestHandlerExecute += new EventHandler(context_PreRequestHandlerExecute);
context.AuthorizeRequest += new EventHandler(context_AuthorizeRequest);
}
void context_AuthorizeRequest(object sender, EventArgs e)
{
HttpContext context = ((HttpApplication)sender).Context;
if (some condition)
{
context.RewritePath(url);
}
}
void context_PreRequestHandlerExecute(object sender, EventArgs e)
{
//We set back the original url on browser
HttpContext context = ((HttpApplication)sender).Context;
if (context.Items["originalUrl"] != null)
{
context.RewritePath((string)context.Items["originalUrl"]);
}
}
}
I have register it in web.config and it is working fine. But when I deploy it in IIS that session and application variables are not throwing null referent Exceptions.
Can anyone help me?
Edit: Do it require extra code to access session/ Application variable for rewritten URLs
?
Have you tried using HTTPContext.Current?
I was able to solve issue (accessing session and application variables in subsequent pages rewritten by custom handler) by adding runAllManagedModulesForAllRequests="true" attribute in modules in web.config.
In my ASP.NET MVC3 web application I'd like to add a small message displaying the number of users currently browsing the site.
I'm currently using Session_Start and Session_End application events to increment or decrement a static property inside Global.asax.
This works, but it isn't precise at all. Since my session timeout is configured to 20mn there's a huge delay between updates.
Is there a more elegant, precise way of doing this?
I've thought of calling an action via AJAX which simply does Session.Abandon() on the window.onbeforeunload javascript event, but this would be called each time the user changed pages. Is there a way to determine when the user closes his browser or leaves the domain?
Any hints, comments or code examples would be welcome!
Here is the relevant part of current code:
public class MvcApplication : System.Web.HttpApplication
{
public static int UsersConnected { get; set; }
protected void Session_Start(object sender, EventArgs e)
{
Application.Lock();
UsersConnected++;
Application.UnLock();
}
protected void Session_End(object sender, EventArgs e)
{
Application.Lock();
UsersConnected--;
Application.UnLock();
}
...
}
Okay this was a bit tricky but I've come with an 'okay' solution.
First, Ive created a static dictionary in Global.asax which will store the IP address of the clients and their last poll date.
public class MvcApplication : System.Web.HttpApplication
{
public static Dictionary<string, DateTime> ConnectedtUsers { get; set; }
protected void Application_Start()
{
AreaRegistration.RegisterAllAreas();
RegisterGlobalFilters(GlobalFilters.Filters);
RegisterRoutes(RouteTable.Routes);
ConnectedtUsers = new Dictionary<string, DateTime>();
}
...
}
Then, in my CommonsController, I've created this action which will add new clients, remove clients which haven't been polled in the last 30 seconds and update the poll date of already registered clients :
public class CommonsController : Controller
{
...
public JsonResult UserConnected()
{
string ip = Request.UserHostAddress;
if (MvcApplication.ConnectedtUsers.ContainsKey(ip))
{
MvcApplication.ConnectedtUsers[ip] = DateTime.Now;
}
else
{
MvcApplication.ConnectedtUsers.Add(ip, DateTime.Now);
}
int connected = MvcApplication.ConnectedtUsers.Where(c => c.Value.AddSeconds(30d) > DateTime.Now).Count();
foreach (string key in MvcApplication.ConnectedtUsers.Where(c => c.Value.AddSeconds(30d) < DateTime.Now).Select(c => c.Key))
{
MvcApplication.ConnectedtUsers.Remove(key);
}
return Json(new { count = connected }, JsonRequestBehavior.AllowGet);
}
}
Finally, on my layout page, added this code which will call my action every 30 seconds and output the result in a span :
<span id="connectedUsers"></span>
<script type="text/javascript">
function PollUsers()
{
$(function() {
$.getJSON("/Commons/UserConnected", function(json){ $('#connectedUsers').text(json.count + " user(s) connected")});
});
}
setInterval(PollUsers, 30000);
</script>
May not be that precise, maybe not that elegant either, but it works. Of course, multiple users from the same IP would count for one user. But it's the best solution I've experimented so far.
you can call a webmethod from javascript on unload body event.
http://www.codeproject.com/Tips/89661/Execute-server-side-code-on-close-of-a-browser
Best regards
I could really do with updating a user's session variables from within my HTTPModule, but from what I can see, it isn't possible.
UPDATE: My code is currently running inside the OnBeginRequest () event handler.
UPDATE: Following advice received so far, I tried adding this to the Init () routine in my HTTPModule:
AddHandler context.PreRequestHandlerExecute, AddressOf OnPreRequestHandlerExecute
But in my OnPreRequestHandlerExecute routine, the session state is still unavailable!
Thanks, and apologies if I'm missing something!
Found this over on the ASP.NET forums:
using System;
using System.Web;
using System.Web.Security;
using System.Web.SessionState;
using System.Diagnostics;
// This code demonstrates how to make session state available in HttpModule,
// regardless of requested resource.
// author: Tomasz Jastrzebski
public class MyHttpModule : IHttpModule
{
public void Init(HttpApplication application)
{
application.PostAcquireRequestState += new EventHandler(Application_PostAcquireRequestState);
application.PostMapRequestHandler += new EventHandler(Application_PostMapRequestHandler);
}
void Application_PostMapRequestHandler(object source, EventArgs e)
{
HttpApplication app = (HttpApplication)source;
if (app.Context.Handler is IReadOnlySessionState || app.Context.Handler is IRequiresSessionState) {
// no need to replace the current handler
return;
}
// swap the current handler
app.Context.Handler = new MyHttpHandler(app.Context.Handler);
}
void Application_PostAcquireRequestState(object source, EventArgs e)
{
HttpApplication app = (HttpApplication)source;
MyHttpHandler resourceHttpHandler = HttpContext.Current.Handler as MyHttpHandler;
if (resourceHttpHandler != null) {
// set the original handler back
HttpContext.Current.Handler = resourceHttpHandler.OriginalHandler;
}
// -> at this point session state should be available
Debug.Assert(app.Session != null, "it did not work :(");
}
public void Dispose()
{
}
// a temp handler used to force the SessionStateModule to load session state
public class MyHttpHandler : IHttpHandler, IRequiresSessionState
{
internal readonly IHttpHandler OriginalHandler;
public MyHttpHandler(IHttpHandler originalHandler)
{
OriginalHandler = originalHandler;
}
public void ProcessRequest(HttpContext context)
{
// do not worry, ProcessRequest() will not be called, but let's be safe
throw new InvalidOperationException("MyHttpHandler cannot process requests.");
}
public bool IsReusable
{
// IsReusable must be set to false since class has a member!
get { return false; }
}
}
}
HttpContext.Current.Session should Just Work, assuming your HTTP Module isn't handling any pipeline events that occur prior to the session state being initialized...
EDIT, after clarification in comments: when handling the BeginRequest event, the Session object will indeed still be null/Nothing, as it hasn't been initialized by the ASP.NET runtime yet. To work around this, move your handling code to an event that occurs after PostAcquireRequestState -- I like PreRequestHandlerExecute for that myself, as all low-level work is pretty much done at this stage, but you still pre-empt any normal processing.
Accessing the HttpContext.Current.Session in a IHttpModule can be done in the PreRequestHandlerExecute handler.
PreRequestHandlerExecute: "Occurs just before ASP.NET starts executing an event handler (for example, a page or an XML Web service)." This means that before an 'aspx' page is served this event gets executed. The 'session state' is available so you can knock yourself out.
Example:
public class SessionModule : IHttpModule
{
public void Init(HttpApplication context)
{
context.BeginRequest += BeginTransaction;
context.EndRequest += CommitAndCloseSession;
context.PreRequestHandlerExecute += PreRequestHandlerExecute;
}
public void Dispose() { }
public void PreRequestHandlerExecute(object sender, EventArgs e)
{
var context = ((HttpApplication)sender).Context;
context.Session["some_sesion"] = new SomeObject();
}
...
}
If you're writing a normal, basic HttpModule in a managed application that you want to apply to asp.net requests through pages or handlers, you just have to make sure you're using an event in the lifecycle after session creation. PreRequestHandlerExecute instead of Begin_Request is usually where I go. mdb has it right in his edit.
The longer code snippet originally listed as answering the question works, but is complicated and broader than the initial question. It will handle the case when the content is coming from something that doesn't have an ASP.net handler available where you can implement the IRequiresSessionState interface, thus triggering the session mechanism to make it available. (Like a static gif file on disk). It's basically setting a dummy handler that then just implements that interface to make the session available.
If you just want the session for your code, just pick the right event to handle in your module.
Since .NET 4.0 there is no need for this hack with IHttpHandler to load Session state (like one in most upvoted answer). There is a method HttpContext.SetSessionStateBehavior to define needed session behaviour.
If Session is needed on all requests set runAllManagedModulesForAllRequests to true in web.config HttpModule declaration, but be aware that there is a significant performance cost running all modules for all requests, so be sure to use preCondition="managedHandler" if you don't need Session for all requests.
For future readers here is a complete example:
web.config declaration - invoking HttpModule for all requests:
<system.webServer>
<modules runAllManagedModulesForAllRequests="true">
<add name="ModuleWithSessionAccess" type="HttpModuleWithSessionAccess.ModuleWithSessionAccess, HttpModuleWithSessionAccess"/>
</modules>
</system.webServer>
web.config declaration - invoking HttpModule only for managed requests:
<system.webServer>
<modules>
<add name="ModuleWithSessionAccess" type="HttpModuleWithSessionAccess.ModuleWithSessionAccess, HttpModuleWithSessionAccess" preCondition="managedHandler"/>
</modules>
</system.webServer>
IHttpModule implementation:
namespace HttpModuleWithSessionAccess
{
public class ModuleWithSessionAccess : IHttpModule
{
public void Init(HttpApplication context)
{
context.BeginRequest += Context_BeginRequest;
context.PreRequestHandlerExecute += Context_PreRequestHandlerExecute;
}
private void Context_BeginRequest(object sender, EventArgs e)
{
var app = (HttpApplication)sender;
app.Context.SetSessionStateBehavior(System.Web.SessionState.SessionStateBehavior.Required);
}
private void Context_PreRequestHandlerExecute(object sender, EventArgs e)
{
var app = (HttpApplication)sender;
if (app.Context.Session != null)
{
app.Context.Session["Random"] = $"Random value: {new Random().Next()}";
}
}
public void Dispose()
{
}
}
}
Try it: in class MyHttpModule declare:
private HttpApplication contextapp;
Then:
public void Init(HttpApplication application)
{
//Must be after AcquireRequestState - the session exist after RequestState
application.PostAcquireRequestState += new EventHandler(MyNewEvent);
this.contextapp=application;
}
And so, in another method (the event) in the same class:
public void MyNewEvent(object sender, EventArgs e)
{
//A example...
if(contextoapp.Context.Session != null)
{
this.contextapp.Context.Session.Timeout=30;
System.Diagnostics.Debug.WriteLine("Timeout changed");
}
}