FileManager Class

This property can be used to prevent users creating large zip files (or other compressed archive files in future) which is CPU intensive. It can be set in <Number> B/KB/MB/GB/TB format (eg. 1024 or 1024 B, 200 KB, 30 MB, 5 GB, 1 TB). Note that this value is the uncompressed size for the action because it's not possible to determine the compressed size before actually doing the compression.

This property is only useful if you have problems downloading large files due to your environment limitations (reverse proxy etc.). For example, Microsoft Forefront UAG can not parse http responses when content-length is larger than 2GB (throws HTTP 500 due to 32-bit integer limit). By setting this property to 2GB, files up to 2GB will be sent with content-length set (default download method) but files larger than 2GB will be sent without content-length and with chunked-transfer encoding so that you can bypass UAG's limitation and successfully download the files. The reason this setting is specified as a threshold is that default download method (content-length set) is always better as it allows the browser to know the whole file size thus show progress information. However with chunked-transfer encoding, the browser will not know the whole file size so it will not be able to show progress information but it will still be able to download the file as long as it receives the stream. So users downloading files smaller than this threshold should not be punished with indeterminate progress but also users downloading files larger than this threshold should still be able to successfully download even there is no progress.

Gets or sets the chunk size used in chunked uploading mode. The default is usually 28.6 MB (or 4MB for ASP.NET Classic before 4.5). The default and highest value is determined from Web.config. For ASP.NET Core and ASP.NET Classic 4.5+, it is determined only from system.webServer/requestLimits/maxAllowedContentLength property in Web.Config. For ASP.NET Classic before 4.5, it is determined additionally from system.web/httpRuntime/maxRequestLength property in Web.Config.

With chunked uploading mode, which is the default mode on modern browsers, file is split into chunks and chunks are uploaded one by one, and then chunks are reassembled back on the server. The reason for using chunked uploading when possible, is to overcome server's default request limitations. By using chunking, normally you don't need to change any settings to allow uploading of very large files out of the box. Currently all upload methods except Html4 uses chunked uploading (Html5 or Flash or Silverlight), this is because Html4 cannot split into chunks and can only send the whole file in a single request (multipart/form-data).

Information on various request size limits:

• IIS by default has 30000000 (28.6 MB) request size limit, controlled by system.webServer/requestLimits/maxAllowedContentLength property in Web.Config, in bytes, maximum value is 4294967295 (4 GB). However maximum value is 2147483647 (2 GB) when the application is running under the NET 4.5 Integrated Pipeline Application Pool. This setting effects FileUploader, as it is an IIS setting, FileUploader cannot automatically override it.
• ASP.NET Core by default has 30000000 (28.6 MB) request size limit, controlled by IHttpMaxRequestBodySizeFeature.MaxRequestBodySize property in code, in bytes, maximum value is unlimited if null. This setting does not effect FileUploader, i.e FileUploader can automatically override it.
• ASP.NET Classic by default has 4096 (4 MB) request size limit, controlled by system.web/httpRuntime/maxRequestLength property in Web.Config, in kilobytes, maximum value is 2097151 (2 GB). This setting effects FileUploader only if you are running under server runtime lower than ASP.NET Classic 4.5 version, i.e when FileUploader cannot automatically override it.