mfc Migrating ISAPI MFC extension (C++) VS2005 DLL project to VS2015. Example:

Example

Purpose of the project: Download particular file based on message id sent as a request from client to server. File will be created on server and transmitted to client.

Here, I haven't share the whole code but shown what is necessary as the purpose is to demonstrate the changes required for migration.

To make the changes. I took the reference of existing afxisapi.h, afxisapi.inl and HttpExt.h which are being shipped with VS2005.

• Use EXTENSION_CONTROL_BLOCK instead of CHttpServerContext. EXTENSION_CONTROL_BLOCK is a main structure which is used by IIS and the ISAPI extension to exchange the information. It contains all the information about new request.

• Remove the dependency of CHttpServer class from your MFC extension class. Remove http command parse message mapping if it is used in your project. Macros like ON_PARSE_COMMAND, BEGIN_PARSE_MAP, END_PARSE_MAP and DEFAULT_PARSE_COMMAND were being removed after VS2005.

• Implement your own GetExtensionVersion, TerminateExtension and HttpExtensionProc function in your MFC extension class which was previously derived from CHttpSever class. These function

• GetExtensionVersion() The GetExtensionVersion function is the first entry-point function in IIS. This function allows your ISAPI extension to register its version information with IIS.

BOOL  CISAPIExtension::GetExtensionVersion( HSE_VERSION_INFO* pVer )
{
    ISAPIVERIFY(
       ::LoadString( AfxGetResourceHandle(),
                          IDS_SERVER,
                          sz,
                          HSE_MAX_EXT_DLL_NAME_LEN) );

       _tcscpy_s( pVer->lpszExtensionDesc, ( strlen( sz ) + 1U ), sz )
}

• HttpExtensionProc() : The HttpExtensionProc function is the main entry point for an ISAPI extension called by IIS. It exposes methods that IIS uses to access the functionality exposed by the extension. Extract the request information from extension control block and do your processing.

DWORD CISAPIExtension::HttpExtensionProc(LPEXTENSION_CONTROL_BLOCK pECB)
{
try
{
    if (strcmp(pECB->lpszMethod, "POST") == 0)
    {
        if (0 < pECB->cbTotalBytes)
        {
            unsigned long ulSize = pECB->cbTotalBytes;
            char* lpszContent = new char[ulSize + 1];
            if (NULL != lpszContent)
            {
                memcpy(lpszContent, pECB->lpbData, ulSize);
                lpszContent[ulSize] = '\0';
                
                std::string message_id;
                // Extract Message id from lpszContent using string operation.

                if(strcmp(pECB->lpszQueryString, "DownloadFile") == 0)
                {            
                    DownloadFileFunction(pECB, message_id));            
                }
                
                delete[] lpszContent;
                lpszContent = NULL;
            }
        }
    }
}    
catch (...)
{

}
return HSE_STATUS_SUCCESS;
}

• Use ServerSupportFunction of EXTENSION_CONTROL_BLOCK instead of TransmitFile function of CHttepServerContext. Previously TransmitFile() were used for File Transfer.
• Use HSE_REQ_TRANSMIT_FILE in ServerSupportFunction for file transfer.
• Pull the transmit file information in HSE_TF_INFO structure.
• Create a callback function (AsyncIOCompletionFunction) that will be called on asynchronous I/O completion.

void WINAPI  AsyncIOCompletionFunction(
EXTENSION_CONTROL_BLOCK * pECB,
PVOID    pContext,
DWORD    cbIO,
DWORD    dwError)
{
    HSE_CUSTOM_ERROR_INFO* pErrorInfo = (HSE_CUSTOM_ERROR_INFO*)pContext;
    DWORD dwIOStatus = dwError == NO_ERROR ?
        HSE_STATUS_SUCCESS :
        HSE_STATUS_ERROR;

    if (NULL != pErrorInfo)
    {
        //
        // log HTTP status code
        //
        pECB->dwHttpStatusCode = atoi(pErrorInfo->pszStatus);

        delete pErrorInfo;
        pErrorInfo = NULL;
    }

    pECB->ServerSupportFunction(
        pECB->ConnID,
        HSE_REQ_DONE_WITH_SESSION,
        &dwIOStatus,
        (LPDWORD)NULL,
        (LPDWORD)NULL);
}

Code snippet for DownloadFileFunction()

HSE_TF_INFO pHSEInfo;

pHSEInfo.hFile            = hFile;
pHSEInfo.dwFlags          = HSE_IO_ASYNC;
pHSEInfo.pHead            = (PVOID) pvHeader;
pHSEInfo.HeadLength       = dwHeaderLen;
pHSEInfo.pContext         = 0;
pHSEInfo.pTail            = 0;
pHSEInfo.TailLength       = 0;
pHSEInfo.BytesToWrite     = 0;
pHSEInfo.Offset           = 0;
pHSEInfo.pfnHseIO         = AsyncIOCompletionFunction; // callback function that will     be called on asynchronous I/O completion
pHSEInfo.pszStatusCode    = LPCSTR("200 OK");

bResult = m_pCtxt->ServerSupportFunction(m_pCtxt->ConnID, HSE_REQ_TRANSMIT_FILE, &pHSEInfo, 0, 0);