How to generate debug information for ISAPI extensions in IIS 6.0

The source code for Microsoft Internet Information Services (IIS) 6.0 contains debug statements to report debug information for ISAPI extensions. This article describes how to configure a computer to generate debug information for ISAPI extensions in IIS 6.0.

To configure a computer to generate debug information for ISAPI extensions, follow these steps.

Create a registry key

To create the required registry key, follow these steps:

Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall your operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.

1. Click Start, click Run, type Regedit.exe, and then click OK.
2. Locate and then click the following registry key:
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\W3SVC\Parameters
3. Right-click Parameters, point to New, and then click Key.
4. Type W3ISAPI, and then press ENTER.
5. Right-click W3ISAPI, point to New, and then click DWORD Value.
6. Type debugflags, and then press ENTER.
7. Right-click debugflags, and then click Modify.
8. In the Value data box, type the flag value that you want, and then click OK. The valid flag values appear in the following table.
   Collapse this tableExpand this table

   Flag value	Statement
   0x80000000	Print a debug line when an attempt is made to load an ISAPI extension.
   0x10000000	Print a debug line when the HttpExtensionProc function for an ISAPI extension is called.
   0x01000000	Print a debug line when an ISAPI extension calls the GetServerVariable function.
   0x02000000	Print a debug line when an ISAPI extension calls the ServerSupportFunction function.
   0x04000000	Print a debug line specific to the ServerSupportFunction function command that is called by an ISAPI extension.
   0x08000000	Do not print the first part of the buffer when printing debug output of functions that use non-string buffers. Examples of functions that use non-string buffers are the ReadClient and WriteClient functions.
   0x00100000	Print a debug line when an ISAPI function fails.
   0x00200000	Print a debug line when an ISAPI function succeeds.
   0x00400000	Print a debug line when an ISAPI extension calls the ReadClient function.
   0x00800000	Print a debug line when an ISAPI extension calls the WriteClient function.
   0xffffffff	Print all debug lines.

Use the WinDbg debugger (Windbg.exe) to view the debug output

To use Windbg.exe to view the debug output, follow these steps:

1. Download and then install the Debugging Tools for Windows. To download the Debugging Tools for Windows, visit the following Microsoft Web site:
   http://www.microsoft.com/whdc/devtools/debugging/default.mspx (http://www.microsoft.com/whdc/devtools/debugging/default.mspx)
2. Run Windbg.exe. By default, the Windbg.exe file is located in the following folder:
   Drive:\Program Files\Debugging Tools for Windows
   Note Drive represents the hard disk on which Windows is installed.
3. On the File menu, click Attach to a Process.
4. In the Attach to Process box, click the inetinfo.exe node, and then click OK.
5. In the Workspace 'base' dialog box, click Yes.