I've an application which has some controller's actions calling slow 3rd party web services. These actions are called using AJAX calls from the page.
I can use async controllers to free ASP.NET thread pool, that's great. But what about session? If I use InProc session and a request made to "slow action" the particular user can't make any request to the application because his session is locked by first "slow" call.
In PHP there is a method session_write_close() which I can use as following:
Accept user's request to slow action
Check rights of the user to access controller/action based on session data
Write something to the session if needed
Call session_write_close(). From this point session is closed by this request and any other request from the same user can access it
Make my slow call (maybe in some async way)
I know that I can disable session state on the controller level using [SessionState] attribute, but that's not the solution.
Any ideas?
I think it could be several scenarios.
1) make changes in controller factory and change it to produce contorllers without session or with some custome session implementation
2) try to read this article about sessionless controllers
Related
In ASP.NET when you have 2 AJAX requests on the same web page calling 2 controller actions, if they use the session then one will lock out the other
You can get readonly access to the session which can help, but not if you want to write to the session
You can override the session class, e.g.
https://www.red-gate.com/simple-talk/dotnet/asp-net/single-asp-net-client-makes-concurrent-requests-writeable-session-variables/, but this doesn't really help for the same reason
In my case the controller action calls a long running external server call. While this is happening ideally the session would be released and saved back to memory, and then when the call is finished the session would be read back in, possibly being blocked if another call is still proceeding
NB Whether or not the external server call is called in an async manner makes no difference unfortunately
Is there any way of doing this? Possibly by overriding some internal classes?
I have a following issue regarding using WCF service from my ASP .NET mvc application. Service requires a callback method to be implemented on the client side. For that I am using wsDualHttpBinding. Callbacks are being invoked and the correct info is recieved (checked using brakepoints multiple times).
The issue lies in the fact that I'm not able to save the data that I recieve when callback "SendComment" is invoked from WCF service. Callback method definition:
public void SendComment(ChatComment cc)
{
Session["Message"] = cc;
}
This is a method that should allow client (in asp .net) to recieve chat messages that are broadcasted to multiple clients from WCF service.
When I try to access Session["Message"] from the controller methods, it's value is null after I have recieved a callback. This is the main problem. I have to find a way to save the value for it to be available in current session context.
Additionally i can't access any of the other session variables I have saved right before the callback is invoked. They are always null.
Besides how do I know when I've recieved the callback? Do I have to use event handlers or somehow call the controller/view from this method?
I've already tried googling for the answer but none of the solutions explicitly state how to access the value after callback has happened.
P.S. Sessions are set to required in WCF Service.
This will not work the way you designed it. A few reasons why not:
You cannot access session from callback.
You cannot call client directly from ASP.Net MVC application.
You have too look for some other solution. I suggest you look into SignalR or if you need something simpler use DB to store data and pool from client.
I am learning Servlet. But don't understand the major difference between HttpSession object and HttpContext object ? As both are used to keep track of the user. But I don't understand , are both of them being accessible across the user or servlet ?
Can anyone provide me an example for this, so I can have clear understanding of it...
Request - Normally used for passing data from jsp to your servlet when you submit the form. When you get redirected to another jsp, your request dies. ie: this attribute lives per user request.please note that http is stateless protocol.so the server will treat every http request as a new request.
Session -session object is basically used to store the values in the session.the data will be preserved until the user terminates the program or closes the browser.Good example will be for storing user credentials. once user is authenticated, Sometimes you may want to check if the user has right access to do on some database operations like add/delete/edit. Once user closes the browser or the session goes idle for x amount minutes (depending on your server setup), the session dies and all info in it will be gone.
Context -context object can be used for multiple users and across multiple browsers.
If it is application specific, consider using context.
If it is user specific, consider using session.
If it is request specific (ex: jsp form submission), consider using request.
Hope this helps.
I need to check some stuff (Cookies) for each request coming to my application.
In ASP.NET we've used HttpModule for this task , the question what should be used in MVC ? Some Global Filter , or I can Use HttpModuler as well, is there Any difference in Request PipeLine between MVC and regular ASP.NET ?
MVC is an abstraction over ASP.NET and therefore their "hooks" really depend at which level you want to inject your logic. An action filter will allow you to hook into MVC specific events:
OnActionExecuting – This method is called before a controller action is executed.
OnActionExecuted – This method is called after a controller action is executed.
OnResultExecuting – This method is called before a controller action result is executed.
OnResultExecuted – This method is called after a controller action result is executed.
Whereas an HttpModule only allows you to hook into ASP.NET (upon which MVC is built) specific events:
BeginRequest - Request has been started. If you need to do something at the beginning of a request (for example, display advertisement banners at the top of each page), synchronize this event.
AuthenticateRequest - If you want to plug in your own custom authentication scheme (for example, look up a user against a database to validate the password), build a module that synchronizes this event and authenticates the user in a way that you want to.
AuthorizeRequest - This event is used internally to implement authorization mechanisms (for example, to store your access control lists (ACLs) in a database rather than in the file system). Although you can override this event, there are not many good reasons to do so.
PreRequestHandlerExecute - This event occurs before the HTTP handler is executed.
PostRequestHandlerExecute - This event occurs after the HTTP handler is executed.
EndRequest - Request has been completed. You may want to build a debugging module that gathers information throughout the request and then writes the information to the page.
So it really depends on when you need to hook in your event and which events you need.
If the HttpModule worked well for you before then it will continue to with Mvc.
The other parts of your question are quite broad in scope and think you'd be as well reading a good article on asp.net-mvc pipeline and extensibility.
I've done similar things using a global action filter. It works quite well, and keeps your code integrated within your application.
An HTTP module works as well, of course, but this will mean seperating the code from your main application and maintaining it seperately. Unless your code spans multiple sites or is used in multiple applications, or needs to work with web forms sites, then I would use a global filter.
I have created a ASMX Web Service which does some Active Directory stuff behind the scene.
As I wish to retain certain information within Web Services under user session, I have decided to put [WebMethod(EnableSession = true)] and start using Session variables.
However, when I turn that option on, the return time from app -> web service -> app has became ridiculously long. (about a minute or more).
If I remove [WebMethod(EnableSession = true)], it is fairly fast.
Anyone know what is going on?
Possible reasons:
Session state is stored out of process (state server/ SQL server) and getting/storing it taking a long time
You are making multiple concurrent requests (including service requests) under the same session. ASP.NET ensures that only one session-full (session read/write) request execute at a time and hence, multiple concurrent requests would queue up.
EDIT :
For #2, obvious solution is to avoid session state use - for example, can you put the relevant information into another store such as cache or database (expensive).
If you are only reading session state in web service then you may take advantage of read-only session state (see IReadOnlySessionState). Read-only session state allows concurrent read-only requests - read/write request will still block all other requests. Now, EnableSession from WebMethod attribute does not support this - it either provides no session or read/write session. So one of the workaround can be to implement your own handler implementing IReadOnlySessionState and then route asmx request to thi handler using a http-module and then switch the handler to default one later. Because your handler requires read-only session state, you will have the read-only session state - see this forum post where such http-module that switches the handler has been given.