State Management :: Why Singleton Returns Same Object In Stateless Environment
Jun 2, 2010
If I run below ASP.NET code, it gives me same output in different post-backs. First Time
Name is = Smith
also After Post-back (Button Click)
Name is = Smith
I feel though I have defined singleton, it should return a new object every time in different ASP.NET post-backs. because once the function "PAGE_LOAD" is completed then there are no reference variables holding singleton object. So there is a change of unloading the singleton class from memory by CLR. that means there is a chance of losing private static reference variable and also single ton object stored. In ASP.NET stateless environment, why is it keeping earlier object in multiple post backs and btw, without having any reference variable to that object. Is this is known danger with singleton in ASP.NET environment?
if using session variables to store and retrieve information is a bad practice? Let me give you some background:
I am developing a site for a friend of mine, and his site is hosted by Go-Daddy. My feeling is that Go-Daddy is not the best place to host a .NET site, but it is what it is.
After the first version of the site was published and people started using it, users immediately started having session time-out problems and null exceptions when referencing session variables. I researched everything I could and tried everything I could think to do, but I just could not correct the issue.
Then, while doing some testing, I discovered that users weren't individually timing-out and losing their session information, but, rather, all users where timing out at exactly the same time, regardless of how long they had been logged in or what they were doing. So, for whatever reason, the server was just dumping all sessions at random intervals.
At this point I needed to move on with the project so I added a number of cookies to replace the session variables, and everything began working properly.
in a hosted environment, should I avoid using session variables? Is it as problamatic as my research and experience would indicate, or is this simply due to the fact that I am working with a poor hosting company in Go-Daddy?
if cookies are disabled at the clients enviorment, what should we use to store the global data or the sessional data, for example now i use APPLICATION["VarName"]=Value;
To store the data, how is it different from
SESSION["VarName"]=Value;
Also if both dont work when cookies disabled , what is the best approach to store the global data
I'm currently developing a website using VS2010 Express/SQL Express 2008, and am using the applications development server to test.
I have created an access layer which effectively takes all my cachable data and creates datasets.
I've also created a system wheras for each dataset, For each dataset I also create a token cached object (a string), which is set to expire before the dataset. The theory behind this is that when my token expires and is removed from cache, it calls a routine to rebuild the dataset, and re-caches the new result, then creates a new token. Think of it as a poor mans SQL dependency.
What this allows me to do is rebuild datasets behind the scenes with little interruption/delay throughout the day. It all works great - for instance when a user updates a table containing 100,000+ records on the site, the dataset rebuilds at hourly intervals reworking and consolidating the data in the background before representing it in a smaller cachable form.
What I would like to know is this. If I was to replace the database during the usable day (only updating the tables that users don't update), lets say adding 50 new records, would it cause the cache to be dropped. The reason I ask is because it the cache remains until its exipry time, I can replace the database and rebuild datasets incorporating new data in the background when the token expires. If the cache is dropped when I update the database, it will mean interuption whilst I reload the datasets and will change my strategy on uploading new data.
I ask the question because I'm currently working on the development server and unable to test in a live server environment at present.
We have an applicaiton that was converted to the new framework using the wizard in Visual Studio 2008. When we install the applicaiton in production and change the iis settings to use the 2.0 framework we start to see these errors in the event viewer on the web servers. We are using SQL Server Session State and have 3 web servers in a load balancer. Object reference not set to an instance of an object.</Message><StackTrace> at System.Web.SessionState.SessionStateModule.PollLockedSessionCallback...
I have a problem.This particular code when used on local machine is working fine, but when it is used on serverit gives an error like " Object reference not set to an instance of an object.Exception Details: System.NullReferenceException: Object reference not set to an instance of an object._isRefresh = _refreshState == (bool) Session["__ISREFRESH"]; "
global.asax:-I have defined a struct (my_struct)-I add a List of structs (List<my_struct>) to Application["MyList"] In default.aspx:-I have defined the exact struct (my_struct) and want to cast the Application["MyList"] object to the List of structs.
example: x = (List<my_struct>)Application["MyList"];
I receive this error "Unable to cast object of type 'System.Collections.Generic.List`1ASP.global_asax+my_struct]' to type 'System.Collections.Generic.List`1[_Default+my_struct]'
I had an xml-serialization which worked fine, but as I have just knew it doesn't work in Opera browser. I think, it's security rules don't allow to write to cookies xml-content.What can I do? Can I use binary serialization or something else?
Anyway, I currently have a ajax based progressbar, which works like this: my long-task stores progress in session. Async callback retrieves progress from session, progressbar is updated. Everybody is happy... not! This only works when the "main loop" of the time-consuming task runs in either codebehind or a class with httpcontext. But all my businnes objects cannot do such thing. So, the next natural spet would be to say "move it to a static class" ProgressHelper or something, but since static classes are shared across all appDomain, I would bump into concurrence problems. So, can i have say a "static list progress" say progress["session1_progress"], progress["session2_progress"], progress["sessionN_progress"]? I cannot really see a way to update progress from inside a task in a business object, which i might want to use also in other plattforms like a desktop app?
I wish to persist a class object across postbacks by using a single session variable/object/whatever.
The class has about a dozen single variable properties; and about a dozen table properties; and several methods. The main table tracks rows of sporting event results. The web site will collect one row at a time for each postback. The data in the object's constructor is based on a dataset, but the data in the class will grow each time I do a postback so I don't want to loose the information in the class. The data isn't very big - it will fill a single computer screen.
Being new to programming I am thinking that I can store the dataset in the session but that would slow down the response time because I the methods would have to be called to refine the data - or maybe I can just store the entire class object in a session.
I am working with asp.net mvc and i am trying to get acces to a object that is in the cache.In the Application_Start() of Global.asax.cs i create and store an object in the cache like this:
Translator translator = new Translator(); HttpContext.Current.Cache.Insert("Translator", translator, null, System.Web.Caching.Cache.NoAbsoluteExpiration, System.Web.Caching.Cache.NoSlidingExpiration);
Translator holds a dictionary with translations.Now i want acces to this object from the cache to use functions and get values from the dictionary.I know i can acces it like this HttpContext.Current.Cache.Get("Translator") or Cache.Get("Translator") in the views But how can i use the functions of the object ? The meaning of the cache is to have a object that is accesable througout the webapp right ?
Do i have to make an object and asses the value of the Cache.Get("Translator") to it, so i can use the functions or is there another solution?
On my local machine I've got a website running which uses the login control to authenticate a user and write a formsauthentication ticket to the client (which is also on the same local machine). At the login process it stores a a small serializable userobject in a session object named Session["appuser"]. Now when I open FF and login to the website all is fine so far... But here's the thing I cannot for the life of me figure out...
When I open IE8 and login to the same website, the session object which was created in FF is completely overwritten with the one created in IE. I thought that every session is unique, but now I'm really starting to feel my knowledge of sessions is almost next to nothing... Is there anyone out there that could tell me why I'm seeing this.
I have a Session Varaible in which I am assinged a List of "MLoad" objects (Ex:- 10 MLoad objects) from the initial search. After that basing some icon click i am trying to get the new filtered results (Ex:- say 1 MLoad object) and assigning them to the public property "ListSearchResults" (See code below). When i do this the original results in the Session are changed(10 MLoad objects are getting replaced with 1 MLoad object ==> which just been filtered). What i have to do so that the "ListSearchResults" in Session is not changed. It is now byref, how to make it byval?
in acreate an object See below code and after retreving t
When I try to save an object reference in a view state it tries to save the object content using serialisation. to save the object reference only to apply to this object instance after postback?
I have a object of Class named "Employee" I need to store the object in the session. what happens if i do not serialize the object and store in the session.
I have a Authorizeclient.aspx.cs page where I set my session value.Authorizeclient.aspx is a blank page. HttpContext.Current.Session["nodeID"]="0". This session value changes from 0 or non zero which depends on the value returned by Database. If no value is returned I assign HttpContext.Current.Session["nodeID"]="0" as the default state else I assign HttpContext.Current.Session["nodeID"]=resolve(nodeID).ToString()
Till this part it works fine as expected. However, I have a requirement that I need to read the nodeID from Session in other application on the same server. I mean this application too is part of the root project where I initially created the Session and set it. The strange thing is the Session["nodeID"] in application gets null "SOMETIMES" Not always. I am trying to read the Session in Page_Load. Sometimes it works fine and sometimes it gets null. Moreover the session object do not die and I can see other keys like Session["Themes"] etc there. The session is in InProc mode and have 20 minutes timeout time.
I am stuck with the issue of concurrent access to Session object. Actually my problem is i m writing to session in frame1 and trying to access that same Session object at the same time in Frame2's Page. I know about the reader/writer lock. I made the enablesessionstate = readonly in the page where i m writing to session. its giving me strange behavior on IE and firefox.
Its working concurrently in IE8 ( means page2 is diplaying modified values while page1 is changing the session object) but does not work in Firefox even page load is not called untill function on page 1 completed. Either anyone can fix my issue with firefox or there is new solution to reader/writer lock so that i can read the session at the same time while writing.
I have a asp.net application where I am saving off into session the user privilege information. From a grid I am bring up a new window by using the window.open. It seems that it is whiping out the values in session. A temporary bandaid I have placed on it is to recall the database if the value is nothing to reset the user object. I have found all over the internet that this is an issue with the window.open in IE 7 and IE 8. Has anyone else run into this and able to actually fix it?
System.InvalidCastException was unhandled by user code
Message=Specified cast is not valid.
Source=App_Web_donate.aspx.cdcab7d2.wqdohvu3 StackTrace: at Donate.LoadUserDetails() in C:UsersSimonDesktopLocal SitesCats ProtectionNewDonate.aspx.vb:line 261 at Donate.btnDonate30_Click(Object sender, EventArgs e) in C:UsersSimonDesktopLocal SitesCats ProtectionNewDonate.aspx.vb:line 205 at System.Web.UI.WebControls.LinkButton.OnClick(EventArgs e) at System.Web.UI.WebControls.LinkButton.RaisePostBackEvent(String eventArgument) at System.Web.UI.WebControls.LinkButton.System.Web.UI.IPostBackEventHandler.RaisePostBackEvent(String eventArgument) at System.Web.UI.Page.RaisePostBackEvent(IPostBackEventHandler sourceControl, String eventArgument) at System.Web.UI.Page.RaisePostBackEvent(NameValueCollection postData) at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)
InnerException: I have made the important bits Bold I have the following code which is generating this error:
[Code]....
I am not entirely sure what is causing it. Its completley intermitent. I am storing all the details of a user filling in a form in a structure, and then assigning that structure to a session variable. This means if they page back, and then page forward again, I can pre-populate the form with the details they have already filled in for their conveinience by using the above code snippet. It appears that it works for a good minute, but if I leave the browser alone any longer than roughly 60 seconds, and then try and page forward to the form again, the exception will fire. While writing this post, the exception has occured in again in firefox, but interestingly, Google Chrome doesn't seem to have this problem. It looks like I can leave chrome alone for as long as I want and it will still work.
