Type Default Value Read Only Description

[Visual Basic]
Default No The module for obtaining URI/HTML data.




This property specifies the module to obtain URI/HTML data.

The TransferModuleType enumeration can take any of the following values:

  • Default — this is currently the same as RetryNetWebRequestOnEngineAccessDenied.
  • EngineTransfer — the engine (i.e. MSHTML/WinINet) obtains the page.
  • NetWebRequest — System.Net.WebRequest is used to obtain the page.
  • RetryNetWebRequestOnEngineAccessDenied — the engine obtains the page. If the engine is denied access to local storage, System.Net.WebRequest is used to obtain the page. (Possibly more than one request sent.)

RetryNetWebRequestOnEngineAccessDenied is useful in restricted environment. When MSHTML downloads web pages, it needs to access the following shell folders (specified in "HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders" in the registry):

  • History — the default value is %LOCALAPPDATA%\Microsoft\Windows\History
  • Cache — the default value is "%LOCALAPPDATA%\Microsoft\Windows\Temporary Internet Files"
  • Cookies — the default value is %APPDATA%\Microsoft\Windows\Cookies

If the folders are not accessible, the fallback folders History, "Temporary Internet Files", and Cookies in %TEMP% are used.

For example, your application uses the "ASP.NET v4.0" application pool and the identity is ApplicationPoolIdentity, you need to grant "IIS APPPOOL\ASP.NET v4.0" access to the folders with %LOCALAPPDATA% = %SystemRoot%\System32\config\systemprofile\AppData\Local and %APPDATA% = %SystemRoot%\System32\config\systemprofile\AppData\Roaming or to the fallback folders with %TEMP% = %SystemRoot%\Temp.

If MSHTML cannot access those folders, ABCpdf with RetryNetWebRequestOnEngineAccessDenied specified will obtain the HTML page using System.Net.WebRequest. In such a case, more than one request may be sent.