Large Uploads in ASP.NET

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FileUp's HttpModule Connection Timeout MaxClientRequestBuffer .NET Settings

ASP.NET Samples FileUp includes many sample ASP.NET applications in both C# and VB.NET. To run the samples, open a browser window and enter the URL http://localhost/SAFileUpSamples. The sample code is in the folder FileUp\Samples.

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The HttpModule

FileUp's HttpModule intercepts selected requests to overcome ASP.NET's inefficient memory utilization and to allow accurate progress indication. The HttpModule intercepts an upload request, reads all the data, and writes it to a temp file chunk by chunk, before forwarding the request to ASP.NET.

For performance reasons, the HttpModule will not intercept all ASP.NET requests. It will intercept ASP.NET requests for files with the extension .uplx. Files with the extension .aspx will not be processed by the filter, and will be sent directly to ASP.NET. This prevents burdening the server with unnecessary use of the HttpModule. So, to use the HttpModule, name your ASP.NET scripts FileName.uplx.

FileUp's automatic installation package will install the HttpModule for FileUp's samples, and create the script mappings for the .uplx extension. See Installing the HttpModule for instructions on installing the HttpModule at the application level or in the Global Assembly Cache.

Upload Size on the Client While FileUp can process uploads of up to 4-GB, most browsers support uploads of up to 2-GB. Larger uploads must be generated by a client-side control that can handle very large transfers, such as SoftArtisans XFile.

Progress Indication in ASP.NET Under ASP.NET, FileUp's progress indicator is handled by the HttpModule. Therefore, to display accurate progress indication in ASP.NET, upload to a file with the .uplx extension.

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ConnectionTimeout

IIS's Connection Timeout property sets a time in seconds at which the server will disconnect an inactive connection. The default value is 900 seconds. To allow very large uploads to complete it may be necessary to increase this value. To reset Connection Timeout:

1. In IIS, right-click Default Web Site and select Properties.



2. Select the Web Site tab.



3. In the Connection Timeout box, enter a new value.

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.NET Settings

In the .NET configuration file for your Web application - web.config or machine.config- there are several attributes that can affect the performance of large uploads. To set these attributes at the machine level, modify machine.config (located in [windows directory]\Microsoft.NET\Framework\[.NET Version Directory]\CONFIG). To set the attributes at the application level, modify your application's web.config file.

You will find the following values in the httpRuntime node of machine.config:

• executionTimeout
  Time in seconds before a request is timed out.



• maxRequestLength
  Maximum request size in kilobytes that ASP.NET will accept.



• appRequestQueueLimit
  Maximum number of requests queued for an ASP.NET application. The default value of appRequestQueueLimit is 100. If your server will be handling more than 100 concurrent requests, increase the value of appRequestQueueLimit.

The following attributes are in the processModel node of machine.config:

• responseDeadlockInterval
  Specifies the time interval, in the format HH:MM:SS, after which the process will be restarted if the following conditions are met:
  • There are queued requests.
  • There has not been a response during this interval.
  The default value of responseDeadlockInterval is 3 minutes. To allow very large uploads, you may have to increase this value. This property must be set in machine.config, not at the application level in web.config. It will affect any response deadlock in ASP.NET and should be used with caution.



• responseRestartDeadlockInterval

Specifies the time, in the format HH:MM:SS, that must elapse after the last restart to cure a deadlock before the process is restarted to cure a deadlock again. This prevents thrashing on processes that require a relatively long startup time. The default value of responseRestartDeadlockInterval is 9 minutes. To allow very large uploads, you may have to increase this value. This property must be set in machine.config, not at the application level in web.config. It will affect any response deadlock in ASP.NET and should be used with caution.


• maxIoThreads

Maximum number of IO threads per CPU in the thread pool. The default value of maxIoThreads is 25. Increasing this value will increase the number of concurrent executing requests, significantly reducing the amount of time it takes to process concurrent requests. This value is particularly important for large uploads using the HttpModule. If you expect many concurrent uploads to your site, you should set maxIoThreads to the number of concurrent uploads that you wish to support.

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