I'm facing a very peculiar issue with sessions being reset without any apparent reason. This happens randomly, once every few tens or hundreds of requests.
My web application is running on windows 2003, IIS 6.0, .NET 1.1. The application has a webpage which populates a bunch of Session variables during its Page_Load event. The data is stored out of process in ASPNET State Service.
After the Page_load event exits and the page is displayed, the user clicks on a button, which retrieves the session data and does some work with it.
And this Button_click is where the issue occurs. On some occasions, the session variable is null, raising a nullRefException.
Our traces show that the sessionID during the Button_click event is a brand new session, with a different ID than the session of the Page_Load event. Thus, the application fails to retrieve the data that was stored during Page_Load. Our event log shows that the session variables for the problematic requests are indeed populated during the Page_load event, and the response is sent without issue, which normally would persist the data.
We have ruled out session timeouts; although a timeout would still result in the same nullRefException, the same session ID from Page_load would be used to retrieve non-existing data. In this case, the sessionID is different than the original.
We are not messing with the ASPNET cookie in any way, we do not use session.abandon, nor do we inadvertedly remove items from the session.
My question is: what server-side factors could cause the cardholder's session to be reset like that? The Application event log does not contain any useful info.
Also, is there anything client-side (e.g. cookie tampering) that could force IIS to assign a new session upon subsequent postbacks of the page?
Many thanks in advance.
I'm not sure if this applies to your situation, but it might help others.
I was designing a website and I found out the hard way, meaning I had to redesign a portion of this site I was working on. When you create or delete a folder (from an asp.net page) within the active IIS folder it resets all sessions for the website. This means every user currently on the site gets their sessions instantly deleted.
If you have control of your the server, store files outside the IIS folder and stream them in as needed. If you don't have control of the server, you will have to remove any work with folders.
Related
I want to execute a function of an object when my application crashes. I have this third party library TMCTL which I am using in one of my form Main. This library is used to communicate with another windows application. Whenever my application is closed, its .Finish(CommID) method has to be executed. I have put this method in form's closing event. But sometimes, my application crashes due to unknown reasons. At that time this function doesn't get executed. This creates problem, when application is restarted.
I want to know is there any other way to execute this function apart from closing event. I tried using UnhandledException event in ApplicationEvents.vb. But I am not sure how to call TMCTL object in ApplicationEvents.vb from my form. I have declared it as Public in my form's code (Public cTmctl As TMCTL). It gives error if I try to call using Main.cTmctl in ApplicationEvents.vb
I don't think can be done this way, and if someone does come up with something I wouldn't trust it.
There are a couple of ways you could do this.
remember when you've started your 3rd party session (setting file, database, JSON file . . .), when the application closes properly you close the session and mark it as closed.
When your app starts again it can check was the last session closed. If yes, it starts another session, if no, it could (if possible) re-use the last session, or close the last session and create another.
or
Have a second service that mediates between your app and the 3rd party service. The new service (lets call it Middle Man), is called by your app to open the session on the 3rd party and to close it. The MM service monitors your app, if it has stopped running - or isn't responding - and there's an open session then it closes that session.
The second approach is helpful if you want the session to time out after some period of inactivity.
We are trying to move from server session (IIS) to Redis-backed session. I updated my web.config with the custom sessionState configuration. I'm finding that only SOME of my key/value pairs are being saved. Of the 5 I expect to be in there, there are only 2. I verified all my code is ultimately hitting HttpContext.Current.Session.Add. I verified that my POCOs are marked as serializable. Looking at monitoring, I see that it adds the first two pairs, then everything after that just doesn't make it. No hit, no rejection, no exceptions. Nothing.
Anyone ever see this? Know where I could start to look to resolve?
TIA,
Matt
Update 1: I've switched to using a JSON serializer to store my data. Same thing. Doesn't seem to be a serialization issue.
Update 2: I've now downloaded the source code, compiled and am debugging it. The method SetAndReleaseItemExclusive, which seems to send the session items to Redis, is only hit once, though it should be hit more than once as my web site handle SSO and bounces from page to page to load the user and such. Have to investigate why it's only firing once...
Figured it out. Turns out that my AJAX request to an "API" endpoint without my MVC app did not have the appropriate session state attached. Therefore, the SetAndReleaseItemExclusive was never called. Adding this fixed it:
protected void Application_PostAuthorizeRequest()
{
if (HttpContext.Current.Request.Url.LocalPath == "/api/user/load")
HttpContext.Current.SetSessionStateBehavior(System.Web.SessionState.SessionStateBehavior.Required);
else
HttpContext.Current.SetSessionStateBehavior(System.Web.SessionState.SessionStateBehavior.ReadOnly);
}
I'm going to preface this by saying that I understand the new Windows 8 application lifecycle and how it is now 100% up to the user to decide if they want to terminate the app or not. So, I guess what I'm looking to find is a way to pseudo-restart my app, although I'm open to other suggestions as I'm pretty new to designing Modern UI apps.
I'm building an app that interfaces with a Web 2.0 service that requires authentication via OAuth. Fortunately the Windows 8 WebAuthenticationBroker makes this simple: it displays an asynchronous modal window that houses the web frame to allow the user to sign in and I get to provide a callback method when its done.
Now, obviously I only want to display this sign-in screen if I don't already have a session key stored for the user in roamingSettings.values. I used the Grid App template in Visual Studio, and I execute these functions in default.js as soon as the app is activated (checking roamingStorage, calling WebAuthBroker, etc). Now, the Grid App template provides a data.js to allow me to define some of the REST endpoints that I want to fetch. The main problem is that I can't fetch these REST endpoints until the user is authenticated! Yet they still have to (at least, I think) be declared in data.js ahead of time. So what I'm doing now to avoid errors in the event that the user isn't signed in, is the following:
if (roamingSettings.values[sessionKey]){
list = getFeedItems(); // my function that issues all the REST calls
} else {
list = new WinJS.Binding.List();
}
This works fine if the app is manually restarted after authentication is complete, but I would really rather have a way of completely reloading the app asynchronously after authentication is complete. I've spent a ton of time on this already and I'm getting extremely annoyed because I've seen other apps do this (Instametrogram, for example).
Any ideas?
To answer the core question here, how do you soft restart: window.location.reload() is all you need. This just does the refresh in place.
However, what you are actually looking to do is reset the datasource on the ListView instance -- all you need to do is get hold of that control at runtime, and re-assign the data source to it. E.g.:
var lv = document.getElementById("myListView");
lv.winControl.itemSource = list;
An example of this should also be in the app you have from when it currently assigns the list to the listview.
There's a website that contains some real time information. I want to have a VB.Net windows application that monitors the page, and when it detects certain events it triggers some actions based on the data in the page.
I've been searching like crazy for some mechanism to "hook" into the browser and hopefully inspect the messages transmitted for the application to know how to react.
I've seen the SHDocVw COM object, which comes very close. But when I use the BeforeNavigate2 event, it only seems to fire for GETs, and once I'm on the page where the information is displayed/refreshed the event is not raised.
Short of reverse engineering the page, or having to write some kind of proxy...is there a good way to do this in VB.Net?
Here's a method you can try:
Create a GreaseMonkey script embedded on the page to hook up events.
When changes occur, collect the changes in an array or display them on the screen.
Create a VB.Net webpage service to listen for POST requests.
Post using AJAX from your GreaseMonkey script to the webpage service, which then writes to a log file/database on your server.
Otherwise the proxy would probably be the next best method, providing the server isn't HTTPS.
We are using NHibernate to manage our persistence in a complex modular windows forms application - but one thought keeps bothering me. We currently open a session on launch and open all objects through that session. I am worried that all loaded objects get loaded into the NHibernate session cache, so that they cant be garbage collected, and ultimately we will end up with the whole database in memory.
This never happens with web applications because web page requests (and even better Ajax requests) represent the perfect short lived transaction so a session can be opened and closed to handle each request.
However if I load an tree of objects in my forms application and put then into a navigation pane on the screen they may stay their for the life of the application - and at any point the user may click on them, resulting in our code needing to navigate the object relationships to other objects (which only works within an NHibernate session).
What do StackOverflow readers do to keep the benefits of NHibernate without the issues I describe?
Ayende and company usually recommend using a session per "conversation". This usually makes the session lifetime last for very short operations, so it behaves more like a web app.
For your tree case, you can use Bruno's solution #2 just fine. The objects can be lazily mapped. Then, every time you need to access a child collection, you start a conversation and reconnect the parent via ISession.Lock. Then when the databinding is done, close that session. Not too much overhead to maintain, just a few lines of code in any form that needs to carry a conversation; you can extend Form and the controls you're using to do this automatically if you're feeling sassy.
The tricky part, then, is concurrent edits from different sessions. Let's not go there!
I open a session when I need one, and I'll close it when I know that I won't need it anymore.
More specifically, for instance, if I have a form which lets me edit Customer information for instance, I'll open a session when the form gets instantiated, and I'll close the Session when the form is closed.
When I have 2 instances of that form open, I also have 2 session open.
I can see a couple of alternatives:
Eager-load the object tree (which, from what I can gather from the documentation is the default)
Detach the objects, intercept the "click" event, and load the data from the database then, with a new session. This one forces you to take care of collections by yourself, instead of relying on nhibernate, which may fall outside of the scope of the question (which asks for the benefits of NHibernate, one of which is collection management)
You can take a look to my posts on how to use uNHAddins to work with session per conversation in a Windows Forms application (uNHAddins is a project with some additionsns to NHibernate led by Fabio Maulo, current NH Lead)
The first post is this
http://gustavoringel.blogspot.com/2009/02/unhaddins-persistence-conversation-part.html
From there you have links to uNHAddins trunk.