IScriptMapInfo::GetModules Method

Retrieves the list of modules for a request handler.

Syntax

virtual PCWSTR GetModules(  
   DWORD* pcchModules = NULL  
) const = 0;  

Parameters

pcchModules
A pointer to a DWORD buffer that receives the length, in characters, of the module list.

Return Value

A pointer to a string that contains a comma-delimited list of modules.

Remarks

The GetModules method retrieves the modules attribute for a request handler that is located in the <handlers> section of the ApplicationHost.config file. This attribute contains a comma-delimited list of modules for the request handler.

For example, if a Web client requests a classic ASP page, GetModules returns "IsapiModule" by default. If a client requests a static file, GetModules returns a comma-delimited list that contains "StaticFileModule", "DefaultDocumentModule", and "DirectoryListingModule" by default.

Example

The following code example demonstrates how to use the IHttpContext::GetScriptMap method to create an HTTP module that retrieves a pointer to an IScriptMapInfo interface. The example then uses the GetModules method to retrieve the list of modules for the request handler that is processing the current request. The module returns the module list to a Web client and then exits.

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

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

        // Retrieve the IScriptMapInfo interface.
        IScriptMapInfo * pScriptMapInfo = pHttpContext->GetScriptMap();

        // Create an HRESULT to receive return values from methods.
        HRESULT hr;

        // Test for an error.
        if (NULL != pScriptMapInfo)
        {
            // Create buffers to store the module list.
            PCWSTR pwszModules;
            PSTR   pszModules;
            DWORD  cchModules = 0;

            // Retrieve the module list.
            pwszModules = pScriptMapInfo->GetModules(&cchModules);

            // Test for an error.
            if (NULL != pwszModules)
            {
                // 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);

                // Test the length of the module list.
                if (cchModules > 0)
                {
                    // Allocate space to store data.
                    pszModules =
                        (PSTR) pHttpContext->AllocateRequestMemory
                        (cchModules + 1);
                    // Test for an error.
                    if (NULL == pszModules)
                    {
                        // Set the error status.
                        hr = HRESULT_FROM_WIN32(ERROR_NOT_ENOUGH_MEMORY);
                        pProvider->SetErrorStatus( hr );
                        // End additional processing.
                        return RQ_NOTIFICATION_FINISH_REQUEST;
                    }
                    // Convert the WCHAR string to a CHAR string.
                    wcstombs(pszModules,
                        pwszModules,cchModules);
                }

                // Return the list of modules to the client.
                WriteResponseMessage(pHttpContext,"Modules: ",
                    (cchModules>0) ? pszModules : "n/a");

                // End additional processing.
                return RQ_NOTIFICATION_FINISH_REQUEST;
            }
        }

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

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,
        0,
        RQ_MAP_REQUEST_HANDLER
    );
}

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

See Also

IScriptMapInfo Interface