Asynchronous HTTP Handler And Using HttpContext In A Background Thread?
Feb 10, 2010
I was reading Walkthrough: Creating an Asynchronous HTTP Handler and noticed they pass the HttpContext from the handler thread and use it in a WaitCallback which runs on a background thread. It makes calls like _context.Response.Write(). Am I correct in assuming that this doesn't violate the fact that HttpContext is not thread safe because the handler thread will not be using it after the async work has started?
Also, Using an HTTPContext across threads has some good information about HttpContext and threads. Is all of HttpContext not thread safe, or just items like Response? Can multiple background threads access the Items property, if only in read mode?
Bit of a long shot, but is there a way in ASP.NET to dynamically get the website's URL [URL] when there is no HttpContext.Current available.
There is no HttpContext because the code is running in a background thread* (but under the ASP.NET AppDomain). I have a background process that sends emails out every evening, and needs to include the Web address, but I don't want to hard code it because of deployments and testing (it changes from [URL] to[URL] and then to [URL] for the live site).
I have a security manager in my application that works for both windows and web, the process is simple, just takes the user and pwd and authenticates them against a database then sets the Thread.CurrentPrincipal with a custom principal. For windows applications this works fine, but I have problems with web applications.
After the process of authentication, when I'm trying to set the Current.User to the custom principal from Thread.CurrentPrincipal this last one contains a GenericPrincipal. Am I doing something wrong? This is my code:
I create custom HTTP handler for auto generating file and I want to tell IIS7 to serve current request like normal static file because I need to use IIS and web.config file to control compression setting and any other HTTP header of current requested file.I know. there is an internal class called StaticFileHandler in ASP.net. But I cannot access it. Or you have any other way to work like this.
We have a web site which implements a central HttpSessionState management in App_Code like this:
[code]...
All of this worked fine ultil we needed to implement a time consuming process in a new thread... In the second thread HttpContext.Current.Session is null (we know its because the current context its different between threads) so everything fails :
Investigating we found that you could pass the session from one thread to another like this:
i redirect a page from http to https using http module begin request handler .i am calling webservice using ajax but it is saying webserice not defined .which otherwise works fineits work fine when rediect page in page_load instead .but i need to add function for https to http in every page. i still not know why ajax is not working when i use http module for redirect
i have the code for asynchronous call to the database. i execute the sql command into the begin method that will executed onto the separate thread. now i want to execute the another database call asynchronously so that this also execute onto the separate thread. code for one database cal is here....
I need an explanation regarding some advice I got on this site. I'm doing a newsletter sending app, and I have my mail sent in a seperate thread so the process doesn't slow down the whole web site. A couple of people advised me to set the threads IsBackground property to true. I did this, but was also courious about what this does, so I googled a bit.
As it turns out, setting the IsBackground property to true indicates that "it's okay if the process shuts down while this thread is still running.". Or as microsoft puts it "Any remaining background threads are stopped and do not complete." I don't know if I got this the wrong way but, wouldn't it be better to leave the IsBackground property to false, so that the spawned thread can complete its work regarding the main thread?
We are using the Facebook API and receive back URLs for profile image thumbnails. Unfortunately the protocol is restricted to just HTTP and it doesn't support HTTPS. The page on our site that hosts the thumbnails is always delivered via HTTPS, and if we use HTTP for the thumbnails the user will receive security warnings from their browser.
Solution:
Build an HTTP Handler that "passes through" the image from the Facebook URL, but allow the handler to be called via HTTPS. Before I started coding I thought I could something like this:
but I ended up having to save the image to an object in memory than write the image to the Response.OutputStream using the image save function.
Current Code:
[Code]....
This seems inefficient but I can't find a way of using the HTTP Handler as I orginally intended. Is there way of accomplishing the goal without creating the image memory and just "passing through" the call?
In my CMS application, I'm trying to intercept all ASP.NET requests, inspect them and then assign custom HttpHandler if necessary or leave default handling when appropriate.I tried setting HttpContext.Current.Handler in Application_BeginRequest but it doesn't seem to work.There is MapRequestHandler event in HttpApplication but it is not available in the Global application class.
I have a page that is using the Ajax asynch file uploader. What I would like to have happen is after the file is uploaded I would like to have it displayed in a list on the page. I am looking for a way to fire a callback event when the file upload is complete. Is it possible using the asynch fileupload control?
I have a thread running in the background that will sleep and pull data from the database when something wakes it up. I am sending the emails using google apps using SmtpClient (code below).
I wanted to know if there is anything i be aware of? I plan to send only one email at a time (a registration or forgot password email). I am a little worried something can happen like an invalid email locking up the thread because i didnt set a timeout or maybe google apps happen to be done and causing the app to blow up. What should i be aware off? I should ask how i should test as well?
Is there a similar function that I can call without requiring a httpcontext?For example if a start a thread doing some stuff i cant use the httpcontext, but i still need to get the path of the app. And no i can't pass the context as an argument or read it from a shared var.
Now imagine that you're writing an ASP.NET app and you've generated a proxy for the service with the async operations. You create an instance of the service, wire service.GetCustomerCompleted to your handler, OnGetCustomerCompleted, and call service.GetCustomerAsync("12345"). In OnGetCustomerCompleted you apply logic to detect that no customer was found and throw a custom exception, or you want to throw the exception found in e.Error, e.g.:
void OnGetCustomerCompleted(object sender, GetCustomerCompletedEventArgs e) { if (e.Error != null) throw new ApplicationException("GetCustomer failed", e.Error); if (String.IsNullOrEmpty(e.Result.FirstName) && String.IsNullOrEmpty(e.Result.LastName)) throw new CustomerNotFoundException(); }
(I've omitted the bits of code that sets up a Customer object and persists it through the calls.) You launch the call to GetCustomerAsync in Page_Load and expect to retrieve the result in a handler wired to Page.OnPreRenderComplete. My question is, how do you catch the exception in your page? I know you can catch it with Global.asax's ApplicationError, but what if you don't want to navigate away from your page?
I have a problem with a Model Popup Extender that monitoring a background thread.
I need to give feedback to the user about tasks that happend in the server side.
So searching on internet this give me a solution [URL]
Launch a thread, passing the Session variable, update a flag and a mesage and show the info in the web with a timer.
almost all, is fine, in one server (sadly, close to production) after the task (and thread) is completed, the Session variable is set to null and the user is redirected to a "Session Expired" Page.
[code].....
I noticed that this is a very slow server and some websites are very slow.
Session is managed with cookies and the timeout is set to 30 min.
I have just recently run into an issue running an asp.net web app under visual studio 2008. I get the error 'type is not resolved for member...customUserPrincipal'. Tracking down various discussion groups it seems that there is an issue with Visual Studio's web server when you assign a custom principal against the Thread.CurrentPrincipal.
I'm glad that I got the error out of the way, but it begs the question "What is the difference between these two methods of setting a principal?". There are other stackoverflow questions related to the differences but they don't get into the details of the two approaches.
I did find one tantalizing post that had the following grandiose comment but no explanation to back up his assertions...
I have a ASP.NET page with a WebMethod that creates an object and runs one of the object's methods in a new thread.I need to access the System.Web.HttpContext.Current.Response.ContentType property from within this thread. Each time I (try to) access it, I receive a NullReferenceException.
When I was localizing my web application I got one strange doubt.
In the first request i set current thread's current culture to user chosen culture. It worked fine for that particular request. But when i browsed for other page, server rendered content in default english culture. I think the reason meight be "http is stateless" means current request is served by a thread whose culture was set properly. Send request will be serverd another thread which does not about previous thread. So we should once again assign culture to this thread. Localization can be done by setting culture to a session variable.
So my question is what is the benifit that we get by setting culture to current thread. With setting to thread we can show the page in user desired language.
