Develop Reference

How to get the number of users in particular page of my application

I have created an application in dnn 7.4 and i want your help can anyone give an idea,
How i can get the numbers of users using particular page or users there in that particular page of my website.
Thanks in advance

To get the real and accurate number of users currently viewing the page you need something holding a channel to the server or sending "ping of life" from the client to the server each second or so.
You may implement it alone using AJAX or you may use framework like SignalR - see these examples:
Get the number of users that are online using SignalR
Tracking Online Users with SignalR

you can just add static variable in the page.
static int userCount= 0;
protected void Page_Load(object sender, EventArgs e)
{
if(!IsPostBack())
userCount++;
}
Aspx code behind is nothing but IHttpHandler which is loaded when w3wp process is initiated...So static variable will be intialized as soon as class is loaded i.e. in this case when application starts and will be live throughout application scope
Note: The above coe will give you count of users visited the page..but you have to do something similar like that...On Page unload you can decrement static to variable to get current user on page
protected void Page_Unload(object sender, EventArgs e)
{
userCount--;
}

How to call Session_End when a browser is closed?

I have two questions. I will split my questions into two sections and give an overview. I'm not entirely sure of the code I need to post so if I have missed some out, please let me know and I will help.
Overview:
When the browser is closed I need to sign the user out.
Question 1:
How do I call Session_End when the browser is closed?
I did some reading on how to close it and it seems that the only way to detect if a Session has ended when a browser has been ended is by using something called 'InProc' in my web config. I gave it an attempt and it didn't seem to change anything at all. So I'm wondering if there is another way around this.
Session_End:
protected void Session_End() {
if (User.Identity.IsAuthenticated) {
}
}
Question 2: How to sign a user out on Session_End?
Once the program has called the void I need to sign the user out as it's causing a bug in my program. I am using the Authentification manager.
Session_End:
protected void Session_End() {
if (User.Identity.IsAuthenticated) {
AuthenticationManager.SignOut();
}
}

Using InProc sessions, the Session_End method is called when the session times out. This is (by default) 20 minutes after the user has last accessed your site (requested a new page). Note that these 20 minutes could have been spent carefuly reading a single page of your site - his session is still closed.
There is no way to detect when a user has closed his browser or navigated away from your site.

You need to use the Global.asax file. It should already contain this Method, all you need to do is add the guts of your code.
protected void Session_End(object sender, EventArgs e)
{
if (User.Identity.IsAuthenticated)
{
AuthenticationManager.SignOut();
}
}

Global.ascx function to detect authenticated users first page visit

I'm currently using the "Session_Start" function within the Global.ascx file to save when an authenticated user visits my site.
This works OK if a users session expires, however as I'm using persistent cookies the user may return to the site within 28 days and this function will not be called and therefore will not be recording in the database that the user has visited.
I've taken a good look at all the functions available within Global.ascx, however I cannot find one that will perform what I need.
Application_Start - triggered only run within life cycle
Application_BeginRequest - each and every request made
Application_AuthenticateRequest - each and every request
Session_Start - when a new session is started
The two events that I believe could be used are Application_BeginRequest or Application_AuthenticateRequest.
Is there any way of limiting the above events to only run specific code on the first visit to a site and not on each request?
Alternatively is there any way of using my master file?
Any suggestions would be very useful.
Cheers

Why don't you implemented by your own? As you mentioned there is an event Application_BeginRequest. I think following might do the trick:
protected void Application_BeginRequest(object sender, EventArgs e)
{
string session_param_name = "SOME_SESSION_ID";
if (HttpContext.Current.Request.Form[session_param_name] == null)
{
//Count
}
else if (HttpContext.Current.Request.QueryString[session_param_name] == null)
{
//Also count
}
}

Refresh page repeat database transaction?

I have over 30 aspx pages, i have discovered a problem recently that if i did any kind of database transaction like insert, update, delete and then after the transaction is complete i pressed F5 or refreshed the page in anyway the same is transaction occur.
I searched for a solution but all i could found is that i have to check for viewstate on each button which is impossible, cause that means there will be a lot of work. There got to be generic solution, please help me in this problem.
Edit:
Here is the code on one of the buttons which change a value in data base to either true or false:
protected void btn_Publish_Click(object sender, EventArgs e)
{
if (Convert.ToBoolean(int.Parse(hf_Published.Value.ToString())))
{
publish(false);
}
else
{
publish(true);
}
}
After the execution of the code if refreshed the page the same code is executed, i noticed that since a break point was placed on this method.

You can try this. I used this in several project and working successfully.
public bool IsRefreshed
{
get
{
if (Convert.ToString(Session["RefreshTimeStamp"]) == Convert.ToString(ViewState["RefreshTimeStamp"]))
{
Session["RefreshTimeStamp"] = HttpContext.Current.Server.UrlDecode(System.DateTime.Now.ToString());
return false;
}
else
{
return true;
}
}
}
protected override void OnPreRender(EventArgs e)
{
base.OnPreRender(e);
ViewState["RefreshTimeStamp"] = Session["RefreshTimeStamp"];
}
protected override void OnLoad(EventArgs e)
{
if (!Page.IsPostBack)
{
Session["RefreshTimeStamp"] = HttpContext.Current.Server.UrlDecode(System.DateTime.Now.ToString());
}
base.OnLoad(e);
}

There IS a generic solution, used for years by thousands of developers.
And the solution is: each time you perform an intrusive process at the server (insert/update/delete) you don't just render the page but rather you redirect the response with 302 to a fresh page with "your transaction succeeded" message.
This way, pressing the F5 will just refresh this message page, not the original page which triggers the transaction.
It is up to you whether or not this is directly applicable in your scenario.
http://en.wikipedia.org/wiki/Post/Redirect/Get

To fix this issue you could check the following:
Disable the submit button when necessary
Add some validation to your code and check for double entries
Redirect the user to another page after submit

Unless it's a real 'transaction' like payments etc. (which others already explained, do redirect etc.),
You could also try defining caching on your pages that interact with the Db or are bottlenecks for your app.
If you wanna have always live info (and it's that 'alive' type of app) then no luck with that solution (but even then), but usually, you can put some reasonable time expiration on how 'fresh' you want your data to be.
Caching ASP.NET Pages

HttpModule Init method is called several times - why?

I was creating a http module and while debugging I noticed something which at first (at least) seemed like weird behaviour.
When I set a breakpoint in the init method of the httpmodule I can see that the http module init method is being called several times even though I have only started up the website for debugging and made one single request (sometimes it is hit only 1 time, other times as many as 10 times).
I know that I should expect several instances of the HttpApplication to be running and for each the http modules will be created, but when I request a single page it should be handled by a single http application object and therefore only fire the events associated once, but still it fires the events several times for each request which makes no sense - other than it must have been added several times within that httpApplication - which means it is the same httpmodule init method which is being called every time and not a new http application being created each time it hits my break point (see my code example at the bottom etc.).
What could be going wrong here? Is it because I am debugging and set a breakpoint in the http module?
It have noticed that it seems that if I startup the website for debugging and quickly step over the breakpoint in the httpmodule it will only hit the init method once and the same goes for the eventhandler. If I instead let it hang at the breakpoint for a few seconds the init method is being called several times (seems like it depends on how long time I wait before stepping over the breakpoint). Maybe this could be some build in feature to make sure that the httpmodule is initialized and the http application can serve requests , but it also seems like something that could have catastrophic consequences.
This could seem logical, as it might be trying to finish the request and since I have set the break point it thinks something have gone wrong and try to call the init method again? Soo it can handle the request?
But is this what is happening and is everything fine (I am just guessing), or is it a real problem?
What I am specially concerned about is that if something makes it hang on the "production/live" server for a few seconds a lot of event handlers are added through the init and therefore each request to the page suddenly fires the eventhandler several times.
This behaviour could quickly bring any site down.
I have looked at the "original" .net code used for the httpmodules for formsauthentication and the rolemanagermodule, etc... But my code isn't any different that those modules uses.
My code looks like this.
public void Init(HttpApplication app)
{
if (CommunityAuthenticationIntegration.IsEnabled)
{
FormsAuthenticationModule formsAuthModule = (FormsAuthenticationModule) app.Modules["FormsAuthentication"];
formsAuthModule.Authenticate += new FormsAuthenticationEventHandler(this.OnAuthenticate);
}
}
Here is an example how it is done in the RoleManagerModule from the .NET framework:
public void Init(HttpApplication app)
{
if (Roles.Enabled)
{
app.PostAuthenticateRequest += new EventHandler(this.OnEnter);
app.EndRequest += new EventHandler(this.OnLeave);
}
}
Does anyone know what is going on?
(I just hope someone out there can tell me why this is happening and assure me that everything is perfectly fine) :)
UPDATE:
I have tried to narrow down the problem and so far I have found that the init method being called is always on a new object of my http module (contrary to what I thought before).
I seems that for the first request (when starting up the site) all of the HttpApplication objects being created and their modules are all trying to serve the first request and therefore all hit the eventhandler that is being added.
I can't really figure out why this is happening.
If I request another page all the HttpApplication's created (and their modules) will again try to serve the request causing it to hit the eventhandler multiple times.
But it also seems that if I then jump back to the first page (or another one) only one HttpApplication will start to take care of the request and everything is as expected - as long as I don't let it hang at a break point.
If I let it hang at a breakpoint it begins to create new HttpApplication's objects and starts adding HttpApplications (more than 1) to serve/handle the request (which is already in process of being served by the HttpApplication which is currently stopped at the breakpoint).
I guess or hope that it might be some intelligent "behind the scenes" way of helping to distribute and handle load and / or errors. But I have no clue.
I hope some out there can assure me that it is perfectly fine and how it is supposed to be?

It's normal for the Init() method to be called multiple times. When an application starts up, the ASP.NET Worker process will instantiate as many HttpApplication objects as it thinks it needs, then it'll pool them (e.g. reuse them for new requests, similar to database connection pooling).
Now for each HttpApplication object, it will also instantiate one copy of each IHttpModule that is registered and call the Init method that many times. So if 5 HttpApplication objects are created, 5 copies of your IHttpModule will be created, and your Init method called 5 times. Make sense?
Now why is it instantiating 5 HttpApplication objects say? Well maybe your ASPX page has links to other resources which your browser will try to download, css, javascript, WebResource.aspx, maybe an iframe somewhere. Or maybe the ASP.NET Worker Process 'is in the mood' for starting more than 1 HttpApplication object, that's really an internal detail/optimisation of the ASP.NET process running under IIS (or the VS built in webserver).
If you want code that's guaranteed to run just once (and don't want to use the Application_StartUp event in the Global.asax), you could try the following in your IHttpModule:
private static bool HasAppStarted = false;
private readonly static object _syncObject = new object();
public void Init(HttpApplication context)
{
if (!HasAppStarted)
{
lock (_syncObject)
{
if (!HasAppStarted)
{
// Run application StartUp code here
HasAppStarted = true;
}
}
}
}
I've done something similar and it seems to work, though I'd welcome critiques of my work in case I've missed something.

Inspect the HttpContext.Current.Request to see, for what request the module's init is fired. Could be browser sending multiple request.
If you are connected to IIS, do check IIS logs to know whether any request is received for the time you are staying at the break point.

Here is a bit of explanation as to what you should use, when, and how they work.
When to use Application_Start vs Init in Global.asax?
Edit: More reading
The ASP Column: HTTP Modules
INFO: Application Instances, Application Events, and Application State in ASP.NET

Examle above locks the IHttpModule for all requests, and then, it frezes the whole application.
If your IHttpModule calls request several times is needed to call HttpApplication method CompleteRequest and dispose the HttpApplication instance of the IHttpModule in EndRequest event in order to remove instance of the HttpApplication like this:
public class TestModule :IHttpModule
{
#region IHttpModule Members
public void Dispose()
{
}
public void Init(HttpApplication context)
{
context.BeginRequest += new EventHandler(context_BeginRequest);
context.EndRequest += new EventHandler(context_EndRequest);
}
void context_EndRequest(object sender, EventArgs e)
{
HttpApplication app = sender as HttpApplication;
app.CompleteRequest();
app.Dispose();
}
void context_BeginRequest(object sender, EventArgs e)
{
//your code here
}
#endregion
}
If you need that IHttpModule requests every time without rerequest on postback use this code above.