Custom Interceptors:
HTTP Module and ISAPI Filter

FileUp comes with two custom interceptors - an HTTP Module for ASP.NET and an ISAPI Filter for ASP.

The HTTP Module

FileUp’s HTTP Module enables very large uploads in ASP.NET. ASP.NET reads an entire HTTP request into memory before making it available to a Web page, which may cause even moderately large file transfers to fail. To overcome ASP.NET’s inefficient memory utilization – and to allow accurate progress indication – the HTTP Module intercepts selected requests and writes the uploaded data to a temp file chunk by chunk, before forwarding the request to ASP.NET.

For performance reasons, the HTTP Module will not intercept all ASP.NET requests. It will only intercept ASP.NET requests for files with the extension .uplx*. (*Note: This file extension is configurable in version 5.) Files with the extension .aspx will not be processed by the interceptor, and will be sent directly to ASP.NET. This prevents burdening the server with unnecessary use of the HTTP Module.

The HTTP Module is a .NET assembly that may be installed globally or at the application level. To install and use the HTTP Module:

1. To make the HTTP Module available to all applications, add it to the Global Assembly Cache.
   
   OR
   
   To make the HTTP Module available to a single application, add it to the application’s “bin” directory.
   
   
2. Name the ASP.NET page that will process large uploads <filename>.uplx.

For detailed information on installing and using the HTTP Module see the FileUp or FileUpEE documentation:

The ISAPI Filter

FileUp's ISAPI filter significantly improves the performance of very large uploads in ASP. The ISAPI filter intercepts an upload request, reads all the data, and writes it to a temp file chunk by chunk, before forwarding the request to ASP. FileUp can upload up to 4-GB with the ISAPI filter. There is no upload size limit when uploading with FileUp Enterprise Edition through the filter.

For performance reasons, the ISAPI filter will not intercept all ASP requests; only those for a file with the extension .upl will be handled by the filter. Files with the extension .asp will not be processed by the filter, and will be sent directly to ASP. This prevents burdening the server with unnecessary use of the ISAPI filter. So, to use the filter, name your ASP scripts FileName.upl.

Because ISAPI filters are installed in IIS at the machine level, they affect all Web applications in all Web sites on the system. For security reasons, FileUpEE's automatic installation package will not install the ISAPI filter in IIS, or the script mapping for the upl extension. To install and use the ISAPI filter:

1. Add FileUp’s ISAPI filter to IIS.
   
   
2. Add a script map for the .upl extension to IIS.
   
   
3. Name the ASP page that will process large uploads <filename>.upl.

For detailed information on installing and using the ISAPI filter see the FileUp or FileUpEE documentation: