Global.asax: Session_End() Behavior

[Guest]

Hi. I am trying to maintain a list of people who are currently "online" in
SQL. I do this by adding a simple entry to a simple PeopleOnline table
whenever someone logs in to my site.

If they manually log OUT of the site, I have no problem deleting them from
the PeopleOnline table. But if they just close the browser, I was assuming
I'd have to use the Session_End() event in Global.asax even though I know
that this will only occur once the user's session has timed out.

But I have two questions about this:

1. When this even occurs, can I still access that user's Session? In other
words, inside the Session_End() function, can I reference the Session[]
object?

2. During development from VS2005, how do I test this? The problem is that
when I close the broswer that I use from within VS, everything sort of dies
so I don't think that the Session_End() ever occurs. How can I debug?

Thanks.

Alex

 

[Guest]

More about this - I *have* figure out that if I set the timeout to something
short. But I still don't know why objects in the session seem to be gone by
the time Session_End occurs.

 

[Juan T. Llibre]

re:
!> I still don't know why objects in the session seem to be gone
!> by the time Session_End occurs.

When the Session_End event fires it's because the session is already gone,
either due to a session timeout or to Session.Abandon having been called in code.

ASP.NET would need to be psychic in order to have a "Pre_Session_End" event.

The only built-in objects available from within the
Session_End event handler are Server and Application.

More about this - I *have* figure out that if I set the timeout to something
short. But I still don't know why objects in the session seem to be gone by
the time Session_End occurs.

Hi. I am trying to maintain a list of people who are currently "online" in
SQL. I do this by adding a simple entry to a simple PeopleOnline table
whenever someone logs in to my site.

If they manually log OUT of the site, I have no problem deleting them from
the PeopleOnline table. But if they just close the browser, I was assuming
I'd have to use the Session_End() event in Global.asax even though I know
that this will only occur once the user's session has timed out.

But I have two questions about this:

1. When this even occurs, can I still access that user's Session? In other
words, inside the Session_End() function, can I reference the Session[]
object?

2. During development from VS2005, how do I test this? The problem is that
when I close the broswer that I use from within VS, everything sort of dies
so I don't think that the Session_End() ever occurs. How can I debug?

Thanks.

Alex

 

[Guest]

Well, I guess what I don't get about that is that, in fact, it is ASP that is
killing the Session at this point (because of timeout). So therefore it
shouldn't have to be "psychic" to implement a "Pre-end-Session." Further, I
have experimented a little and, in fact, I *can* get objects back out of the
Session within the Global.asax Session_End() event. There are some strange
differences, but simple objects in Session[] seem to be reliably available.

Alex

re:
!> I still don't know why objects in the session seem to be gone
!> by the time Session_End occurs.

When the Session_End event fires it's because the session is already gone,
either due to a session timeout or to Session.Abandon having been called in code.

ASP.NET would need to be psychic in order to have a "Pre_Session_End" event.

The only built-in objects available from within the
Session_End event handler are Server and Application.

More about this - I *have* figure out that if I set the timeout to something
short. But I still don't know why objects in the session seem to be gone by
the time Session_End occurs.

Hi. I am trying to maintain a list of people who are currently "online" in
SQL. I do this by adding a simple entry to a simple PeopleOnline table
whenever someone logs in to my site.

If they manually log OUT of the site, I have no problem deleting them from
the PeopleOnline table. But if they just close the browser, I was assuming
I'd have to use the Session_End() event in Global.asax even though I know
that this will only occur once the user's session has timed out.

But I have two questions about this:

1. When this even occurs, can I still access that user's Session? In other
words, inside the Session_End() function, can I reference the Session[]
object?

2. During development from VS2005, how do I test this? The problem is that
when I close the broswer that I use from within VS, everything sort of dies
so I don't think that the Session_End() ever occurs. How can I debug?

Thanks.

Alex

 

[Juan T. Llibre]

re:
!> I *can* get objects back out of the Session
!> within the Global.asax Session_End() event.

Indeed, you can. The Session doesn't *end* until the event has finished executing.

The limitation I noted is for the *built-in* objects, i.e.,
Request, Response, Server, Application, and Session.

Out of those, the only ones available from within the
Session_End event handler are Server and Application.

While you could save an existing session variable to a log, by using
Server.MapPath, for example, you can't set a new session variable.

You can't response.write nor use context.current, either.
There's a lot you *can* do, however.

You need to remember, though, that Session_End may not fire under some circumstances,
so its use may not be as reliable as doing cleanup and logging when it *does* fire.

Well, I guess what I don't get about that is that, in fact, it is ASP that is
killing the Session at this point (because of timeout). So therefore it
shouldn't have to be "psychic" to implement a "Pre-end-Session." Further, I
have experimented a little and, in fact, I *can* get objects back out of the
Session within the Global.asax Session_End() event. There are some strange
differences, but simple objects in Session[] seem to be reliably available.
Alex

re:
!> I still don't know why objects in the session seem to be gone
!> by the time Session_End occurs.

When the Session_End event fires it's because the session is already gone,
either due to a session timeout or to Session.Abandon having been called in code.

ASP.NET would need to be psychic in order to have a "Pre_Session_End" event.

The only built-in objects available from within the
Session_End event handler are Server and Application.

More about this - I *have* figure out that if I set the timeout to something
short. But I still don't know why objects in the session seem to be gone by
the time Session_End occurs.

:

Hi. I am trying to maintain a list of people who are currently "online" in
SQL. I do this by adding a simple entry to a simple PeopleOnline table
whenever someone logs in to my site.

If they manually log OUT of the site, I have no problem deleting them from
the PeopleOnline table. But if they just close the browser, I was assuming
I'd have to use the Session_End() event in Global.asax even though I know
that this will only occur once the user's session has timed out.

But I have two questions about this:

1. When this even occurs, can I still access that user's Session? In other
words, inside the Session_End() function, can I reference the Session[]
object?

2. During development from VS2005, how do I test this? The problem is that
when I close the broswer that I use from within VS, everything sort of dies
so I don't think that the Session_End() ever occurs. How can I debug?

Thanks.

Alex

 

[=?ISO-8859-1?Q?G=F6ran_Andersson?=]

re:
!> I *can* get objects back out of the Session
!> within the Global.asax Session_End() event.

Indeed, you can. The Session doesn't *end* until the event has finished executing.

The limitation I noted is for the *built-in* objects, i.e.,
Request, Response, Server, Application, and Session.

Out of those, the only ones available from within the
Session_End event handler are Server and Application.

While you could save an existing session variable to a log, by using
Server.MapPath, for example,

You can't use Server.MapPath in Session_End, as there is no page to make
the path relative to.

you can't set a new session variable.

Of course you can. It will only live during the execution of the
Session_End method, though, as the Session object goes away after that.

 

[Juan T. Llibre]

re:
!> You can't use Server.MapPath in Session_End, as there is no page to make the path relative to.

Server.MapPath works in the Session_Start event.

Retrieve the path in Session_Start, store it in a variable,
and then use this variable in the Session_End event.

The variable has to be declared as Shared.

re:
!>> you can't set a new session variable.
!> Of course you can. It will only live during the execution of the
!> Session_End method, though, as the Session object goes away after that.

Which means...you can't use it, doesn't it ?

 

[=?ISO-8859-1?Q?G=F6ran_Andersson?=]

re:
!>> you can't set a new session variable.
!> Of course you can. It will only live during the execution of the
!> Session_End method, though, as the Session object goes away after that.

Which means...you can't use it, doesn't it ?

No, it doesn't. It means that you can only use it as long as it exists,
which is the duration of the call to the Session_End method.

There is hardly any reason to create any session variables at that
stage, but there is nothing that prevents it.

 

[Juan T. Llibre]

re:
!> There is hardly any reason to create any session variables at that stage

You mean : "there is *no* reason to create any session variables at that stage",
primarily because you can't *do anything* with a new session variable at that stage.

re:
!> there is nothing that prevents it

Have you actually tried to do something useful with a new
session variable you have succeed in creating at that stage ?

If you can provide an example, maybe I'll have an easier time understanding your point.

 

[Steven Cheng[MSFT]]

Hi Alex,

If you want to do is maintain a online user table, are those users
authenticated user(your application is secured through forms authentication
or...)? If the users you want to count are forms authenticated user, you
can use membership provider's support to get online user number. It use a
database field to track the last activity time of each user and calculate
online users based on this.

If the users are simply based on Session, I also suggest you create a
global online user table(use sessionID as key) to track all the online
users. And in addition to session_end event, you'd better also use a
background timer(thread) to constantly check the last visit timestamp of
each table entry, this entry can be updated each time the user visit the
site. And the entry will be removed in ether of the following cases:

1. session_end event fire for the certain session

2. background timer detect that the timestamp hasn't been updated for a
certain period.

Sincerely,

Steven Cheng

Microsoft MSDN Online Support Lead


This posting is provided "AS IS" with no warranties, and confers no rights.

 

[=?ISO-8859-1?Q?G=F6ran_Andersson?=]

re:
!> There is hardly any reason to create any session variables at that stage

You mean : "there is *no* reason to create any session variables at that stage",

No, I don't.

primarily because you can't *do anything* with a new session variable at that stage.

Of course you can do something with a session variable. There is hardly
any reason, though.

re:
!> there is nothing that prevents it

Have you actually tried to do something useful with a new
session variable you have succeed in creating at that stage ?

No, I haven't. I don't need to try every single thing that I discuss in
newsgroups to know how it works. Sometimes I even answer questions about
things that I didn't even knew existed before I read the question...

If you can provide an example, maybe I'll have an easier time understanding your point.

ShoppingCart.Remove(); // uses session["cartId"]
session["cartId"] = session["secondaryCartId"];
ShoppingCart.Remove();

 

[Juan T. Llibre]

re:
!> ShoppingCart.Remove(); // uses session["cartId"]
!> session["cartId"] = session["secondaryCartId"];
!> ShoppingCart.Remove();

You want that code to run every time a session ends ?

What will you do with session["cartId"] , now that you have created it ?

re:
!> There is hardly any reason to create any session variables at that stage

You mean : "there is *no* reason to create any session variables at that stage",

No, I don't.

primarily because you can't *do anything* with a new session variable at that stage.

Of course you can do something with a session variable. There is hardly any reason, though.

re:
!> there is nothing that prevents it

Have you actually tried to do something useful with a new
session variable you have succeed in creating at that stage ?

No, I haven't. I don't need to try every single thing that I discuss in newsgroups to know how it
works. Sometimes I even answer questions about things that I didn't even knew existed before I
read the question...

If you can provide an example, maybe I'll have an easier time understanding your point.

ShoppingCart.Remove(); // uses session["cartId"]
session["cartId"] = session["secondaryCartId"];
ShoppingCart.Remove();

 

[=?ISO-8859-1?Q?G=F6ran_Andersson?=]

re:
!> ShoppingCart.Remove(); // uses session["cartId"]
!> session["cartId"] = session["secondaryCartId"];
!> ShoppingCart.Remove();

You want that code to run every time a session ends ?

What will you do with session["cartId"] , now that you have created it ?

You missed the comment in the code? Ok, will it be clearer if I rewrite
the example like this?

session["UsedByRemove"] = session["CartId1"];
ShoppingCart.Remove();
session["UsedByRemove"] = session["CartId2"];
ShoppingCart.Remove();