I'm in the process of disabling asp-sessions completely from a site. Its quite a large and complex site, but we're not using the session object programatically anywhere, so I'm just curious if anyone know of any "hidden" issue that may occur if you disable sessions? Viewstates, ajax etc? We're using Dundas components for charting and mapping, but they seems to work ok when running on our test servers.
Check the session events in global.asax. There's one for start and one for end. Make sure nothing is happening there, and you should be be good to go. Assuming the Session type is inproc.
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Since crawlers and most bots don't use cookies, they create a lot of unnecessary sessions. At least for identified bots we'd like to avoid creating a session.
We're using SqlInMemoryProvider which doesn't appear to be open source.
https://cloudblogs.microsoft.com/sqlserver/2014/07/10/new-asp-net-session-state-provider-for-sql-server-in-memory-oltp/
Is there a way to run code to intercept session creation for certain conditions? My guess is one would need access to the custom SqlInMemoryProvider to achieve that. But maybe i'm missing something. ;)
Technology: Asp.Net Webforms, don't bother advising for MVC, thanks ;)
Answer for other people in my situation.
There are no hooks.
Everything needs to be done in the custom session-state store provider.
It's possible to use the free disassembler DotPeek by JetBrains.
One can dissassemble an existing state provider to c# code.
After that the code can be extended, for example detect known bots with a library (for example) https://github.com/totpero/DeviceDetector.NET and prevent such sessions from being created.
I need to have a new session per browser window/tab. I am aware of the fact that ASP.NET assigns one session per process. I am also aware that browsers share this session between all open tabs/windows of the app. However, I need to come up with a way to create a new session for a new tab/window.
Cookieless session-state is not an option also. I already looked at that. I am looking to keep URL's clean.
I looked at the following solutions.
1) asp.net - session - multiple browser tabs - different sessions?. This solutions suggests using IsPostBack property, which is not available in MVC.
2) https://sites.google.com/site/sarittechworld/track-client-windows. This one looks very complex and I don't fully understand the javascript magic that is happening in it. I don't want to put in a solution that I don't understand. Also, I am not fully aware of any security holes that this solution may create.
Can someone point me in the right direction?
The only way to achieve this is to append the session id in the url which is what cookieless sessions are intended to do. Unfortunately you seem to have ruled out this possibility due to the ugly urls it produces.
I've created a NuGet package called ASP.NET MVC Conversational Session. Here you find more information: http://blog.micic.ch/net/asp-net-mvc-conversational-session
I released the first version yesterday. Have a look at the demo code or download the demo solution and let me know if there are things to improve. :)
EDIT: By default: The "identifier" is passed via URL when you use the appropriate extension method in the View. But you can add the identifier on your own. It gives you more flexiblity. (For example when you have links which are not generated via #Html.ActionLink.. etc.)
I'm working on an MVC3 app and I've come across an issue with objects being cached unintentionally.
My code is creating objects from calls to a separate custom business logic dll.
This business logic dll gets data from a database.
After I change data in the database, I'm still seeing the old data, even after closing my browser and re-running the application. It's not a browser caching issue because I can see it when I'm debugging in the development environment.
In development, if I stop the asp.net development server, then re-run the app, I get the new data.
In IIS, if I restart the website, I get the new data.
Any idea why asp.net is caching and re-using these objects, even after they have gone out of scope?
The business logic dll does have some caching built into it, so maybe that's the main issue. In that case, I guess the question is whether there is some way I can tell asp.net to wipe out the objects once the session is over.
There's no caching by default in ASP.NET MVC3, at least no caching of data. Make sure your IIS settings are correct and you don't accidentally use the OutputCacheAttribute.
As for caching in the business layer: I've seen at least three caching-related problems in the last two days. Keep in mind: Caching is tricky, and so are static variables. If it's not necessary, don't do it. Caching is extremely powerful, but it's also dangerous. That is also true for the beforementioned OutputCacheAttribute.
It sounds to me like you're creating your data context statically, rather than creating a new one and destroying it after ever request. This is a bad thing to do for a lot of reasons.
When you say that business layer has "some cacheing", what does that mean? How are you cacheing?
We store two objects in session. Somehow, one of the objects from another user got loaded into a different user's session. The user should have had no access to this particular data, and as soon as they saw it they knew something was very wrong.
We have visual proof of the data that was presented to him, and there is certainly no way it could've happened unless the sessions got mixed up. This is a very scary situation which we can not figure out (we can not reproduce it). The only answer for us is to blame ASP.NET StateServer for mixing the session variables up, which is completely unacceptable and puts us in a bad position.
Our applications are ASP.NET 2.0 apps running on Windows Server 2003 with IIS6, using the StateServer cookieless="false" session mode and FormsAuthentication.
Has anybody else had this problem? How can we resolve it?
We ran into this exact issue in my previous company and took 3 weeks to debug it. ASP.NET was giving a user someone else's session state. It was really impossible to duplicate in a debug environment.
The fix when we found it was just something in web.config. I don't fully remember it, so I spent some time googling. I believe the issue had something to do with output caching. Take a look at this article under "Sessions and Output Caching".
http://download.microsoft.com/download/3/a/7/3a7fa450-1f33-41f7-9e6d-3aa95b5a6aea/MSDNMagazineJuly2006en-us.chm (the article is titled Keep Sites Running Smoothly By Avoiding These 10 Common ASP.NET Pitfalls by Jeff Prosise in July 2006 edition of MSDN magazine)
If that sounds like your scenario, then the fix might just be disabling the enableKernelOutputCache option in web.config.
Good luck.
Look for bugs in your own code first - this is by far the most likely explanation. E.g. using static fields or other shared memory such as the ASP.NET cache for user-specific data.
Possible answer - similar isue reported using cookieless session state.
session showing something wrong
Edit - Added
Another possible answer:
An ASP.NET page is stored in the HTTP.sys kernel cache in IIS 6.0 when the ASP.NET page generates an HTTP header that contains a Set-Cookie response
How many times did it occur? Did you check for users using browser back or sending links to each other with session ids?
One way to check for sure about State Server bug is to switch to another session manager, fallback to in-proc if you can or use SQL Server but would be better to find a way to reproduce the bug it first so you could test it.
Could the two crossed users both be using the same cacheing proxy? If so, then one user might see data that was cached for another user if the URLs matched, especially if the proxy isn't well behaved.
Wasn't this the main problem with the Google Web Accelerator project (now discontinued)?
Had this problem, turned out to be an OutputCache attribute on a partial view.
I recently had a discussion on another forum with another developer and the topic was Code Reuse in ASP.NET. The stated scenario was that he needs to update code frequently on Production servers during server uptimes, and this results in Session getting reset for all users. He is avoiding putting shared code or classes into the App_Code folder or precompiled DLL's into the Bin folder because any updates will also refresh the Session.
The solution he has come up with is to put his shared code into UserControls and reference them wherever required. This enables him to update only the UserControl files which would be recompiled dynamically on next request without forcing a Session restart. Note that the Usercontrols are not intended to have any UI, they probably only house some business logic.
I tried to convince him against this because it felt intrinsically wrong to me - but I could not provide any hard facts to support my claim that this was a very bad way of doing things. The only thing I could think of is that it violates the principle of separation of business logic from UI. Am I grossly mistaken or are there concrete reasons why this should not be done? Links or examples would be helpful.
Note: Using out-of-process Session state is not an option at present, nor have they been able to decide on scheduled downtimes. Also, since this is a site under active development, they don't seem to be using any sort of professional deployment model yet.
Thanks in advance.
Edit: Additionally, it would be helpful if someone could clarify exactly why the Session restarts in the above mentioned cases.
It does seem like an unusual approach, and persistent session is the obvious answer. Assuming that reasons not to use persistent session are legitimate, sometime you just have to go with whatever works. I'd make a point of clearly documenting in the source files the unusual use of usercontrols and live with it.
To answer the why does session get reset edit. With in process session all the session data is in memory as part of your application. Various changes to the web site (e.g. web.config and others I don't recall off the top of my head) cause the application to restart wiping out all current state in your application. Persisting to SQL or the out of process session state server would allow the application to reset and lose any state without affecting the session data.
It sounds like the main problem is that he's updating production code too frequently. Other than that, UserControls seem like a perfectly reasonable place to put business logic, especially if you have a good naming convention for them or can put them in a common folder.
May i ask, why isn't out-of-process session state an option, really?
Since this guy seems to put in so much effort to get around this "problem", wouldn't he be better off looking at better solutions? out-of-process session state is the only good solution.
I'll agree with Dennis, there are really no issues moving from inproc to the state server. Not sure what your dev/deployment platforms are, but they should include a session state service - start that up, change your web.config, and the problem is solved.
it's a clever (and ugly) solution to a common problem
The main problem is the architecture of such system; the code that needs to be updated can be put on a different service outside his web app, his code behind can then call these services, and the services can be updated when needed without affecting the web app
Every base has been covered already, but I really hate bad practices like this. If the guy can't simply change to a state server to fix the problem that he has, then he doesn't really deserve the help. What would happen if he put his class in the root folder of the project and compiled it independently? Either way, I would think this guy is a bad developer for not thinking about scalability, and not planning for downtime. What I'm guessing is he doesn't have a development environment available. Tsk tsk tsk.
As an answer to your question, as stated by everyone else, put the code in a user control, and document well.