IHttpContext::DisableNotifications Method

Article
03/09/2018

Disables specific notifications that are pending for this request in the current module.

Syntax

virtual VOID DisableNotifications(  
   IN DWORD dwNotifications,  
   IN DWORD dwPostNotifications  
) = 0;

Parameters

dwNotifications
[IN] A DWORD that contains a bitmask that specifies the request notifications to disable for this module.

dwPostNotifications
[IN] A DWORD that contains a bitmask that specifies the post-request notifications to disable for this module.

Return Value

VOID.

Remarks

You can use the DisableNotifications method to specify which notifications or post-request notifications you want to disable for the current request. For example, if a module that you are creating has registered for the RQ_AUTHENTICATE_REQUEST and RQ_AUTHORIZE_REQUEST notifications, your module could be configured to ignore the RQ_AUTHORIZE_REQUEST notification based on conditions that are processed in the RQ_AUTHENTICATE_REQUEST notification.

Note

Notifications can be disabled only for the current request and in the current module. The only way to disable notifications that are implemented in other modules would be to return RQ_NOTIFICATION_FINISH_REQUEST from your module.

Note

Notifications can be disabled only for deterministic events; they cannot be disabled for nondeterministic events. For more information, see Comparing Native-Code and Managed-Code Notifications.

Example

The following example demonstrates how to use the DisableNotifications method to create an HTTP module that disables a pending CHttpModule::OnPostBeginRequest notification on the current request.

#define _WINSOCKAPI_
#include <windows.h>
#include <sal.h>
#include <httpserv.h>

// Create the module class.
class MyHttpModule : public CHttpModule
{
public:
    REQUEST_NOTIFICATION_STATUS
    OnBeginRequest(
        IN IHttpContext * pHttpContext,
        IN IHttpEventProvider * pProvider
    )
    {
        UNREFERENCED_PARAMETER( pProvider );

        // Clear the existing response.
        pHttpContext->GetResponse()->Clear();
        // Set the MIME type to plain text.
        pHttpContext->GetResponse()->SetHeader(
            HttpHeaderContentType,"text/plain",
            (USHORT)strlen("text/plain"),TRUE);

        // Return a message to the client to indiciate the notification.
        WriteResponseMessage(pHttpContext,
            "\nNotification: ","OnBeginRequest");

        // Buffer to store the byte count.
        DWORD cbSent = 0;
        // Flush the response.
        pHttpContext->GetResponse()->Flush(false,true,&cbSent,NULL);

        // Specify which notifications to disable.
        // (Defined in the Httpserv.h file.)
        pHttpContext->DisableNotifications(0,RQ_BEGIN_REQUEST);

        // Return processing to the pipeline.
        return RQ_NOTIFICATION_CONTINUE;
    }

    REQUEST_NOTIFICATION_STATUS
    OnPostBeginRequest(
        IN IHttpContext * pHttpContext,
        IN IHttpEventProvider * pProvider
    )
    {
        UNREFERENCED_PARAMETER( pProvider );

        // Return a message to the client to indiciate the notification.
        WriteResponseMessage(pHttpContext,
            "\nNotification: ","OnPostBeginRequest");

        // Return processing to the pipeline.
        return RQ_NOTIFICATION_CONTINUE;
    }

    REQUEST_NOTIFICATION_STATUS
    OnAcquireRequestState(
        IN IHttpContext * pHttpContext,
        IN IHttpEventProvider * pProvider
    )
    {
        UNREFERENCED_PARAMETER( pProvider );

        // Return a message to the client to indiciate the notification.
        WriteResponseMessage(pHttpContext,
            "\nNotification: ","OnAcquireRequestState");

        // End additional processing.
        return RQ_NOTIFICATION_FINISH_REQUEST;
    }

private:

    // Create a utility method that inserts a name/value pair into the response.
    HRESULT WriteResponseMessage(
        IHttpContext * pHttpContext,
        PCSTR pszName,
        PCSTR pszValue
    )
    {
        // Create an HRESULT to receive return values from methods.
        HRESULT hr;
        
        // Create a data chunk.
        HTTP_DATA_CHUNK dataChunk;
        // Set the chunk to a chunk in memory.
        dataChunk.DataChunkType = HttpDataChunkFromMemory;
        // Buffer for bytes written of data chunk.
        DWORD cbSent;

        // Set the chunk to the first buffer.
        dataChunk.FromMemory.pBuffer =
            (PVOID) pszName;
        // Set the chunk size to the first buffer size.
        dataChunk.FromMemory.BufferLength =
            (USHORT) strlen(pszName);
        // Insert the data chunk into the response.
        hr = pHttpContext->GetResponse()->WriteEntityChunks(
            &dataChunk,1,FALSE,TRUE,&cbSent);
        // Test for an error.
        if (FAILED(hr))
        {
            // Return the error status.
            return hr;
        }

        // Set the chunk to the second buffer.
        dataChunk.FromMemory.pBuffer =
            (PVOID) pszValue;
        // Set the chunk size to the second buffer size.
        dataChunk.FromMemory.BufferLength =
            (USHORT) strlen(pszValue);
        // Insert the data chunk into the response.
        hr = pHttpContext->GetResponse()->WriteEntityChunks(
            &dataChunk,1,FALSE,TRUE,&cbSent);
        // Test for an error.
        if (FAILED(hr))
        {
            // Return the error status.
            return hr;
        }

        // Return a success status.
        return S_OK;
    }
};

// Create the module's class factory.
class MyHttpModuleFactory : public IHttpModuleFactory
{
public:
    HRESULT
    GetHttpModule(
        OUT CHttpModule ** ppModule, 
        IN IModuleAllocator * pAllocator
    )
    {
        UNREFERENCED_PARAMETER( pAllocator );

        // Create a new instance.
        MyHttpModule * pModule = new MyHttpModule;

        // Test for an error.
        if (!pModule)
        {
            // Return an error if the factory cannot create the instance.
            return HRESULT_FROM_WIN32( ERROR_NOT_ENOUGH_MEMORY );
        }
        else
        {
            // Return a pointer to the module.
            *ppModule = pModule;
            pModule = NULL;
            // Return a success status.
            return S_OK;
        }            
    }

    void Terminate()
    {
        // Remove the class from memory.
        delete this;
    }
};

// Create the module's exported registration function.
HRESULT
__stdcall
RegisterModule(
    DWORD dwServerVersion,
    IHttpModuleRegistrationInfo * pModuleInfo,
    IHttpServer * pGlobalInfo
)
{
    UNREFERENCED_PARAMETER( dwServerVersion );
    UNREFERENCED_PARAMETER( pGlobalInfo );

    // Set the request notifications and exit.
    return pModuleInfo->SetRequestNotifications(
        new MyHttpModuleFactory,
        RQ_BEGIN_REQUEST | RQ_ACQUIRE_REQUEST_STATE,
        RQ_BEGIN_REQUEST
    );
}

Your module must export the RegisterModule function. You can export this function by creating a module definition (.def) file for your project, or you can compile the module by using the /EXPORT:RegisterModule switch. For more information, see Walkthrough: Creating a Request-Level HTTP Module By Using Native Code.

You can optionally compile the code by using the __stdcall (/Gz) calling convention instead of explicitly declaring the calling convention for each function.

Requirements

Type	Description
Client	- IIS 7.0 on Windows Vista - IIS 7.5 on Windows 7 - IIS 8.0 on Windows 8 - IIS 10.0 on Windows 10
Server	- IIS 7.0 on Windows Server 2008 - IIS 7.5 on Windows Server 2008 R2 - IIS 8.0 on Windows Server 2012 - IIS 8.5 on Windows Server 2012 R2 - IIS 10.0 on Windows Server 2016 Technical Preview
Product	- IIS 7.0, IIS 7.5, IIS 8.0, IIS 8.5, IIS 10.0 - IIS Express 7.5, IIS Express 8.0, IIS Express 10.0
Header	Httpserv.h