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IHttpUrlInfo::IsFrequentlyHit Method

IIS 7.0

Returns a Boolean value that indicates whether the URL is requested frequently.

virtual BOOL IsFrequentlyHit(
   VOID
) const = 0;

This method takes no parameters.

true if the URL is frequently requested; otherwise, false.

The IsFrequentlyHit method retrieves a Boolean value that indicates whether the URL for the current request is frequently requested by Web clients. For example, if you were writing a custom HTTP compression module for IIS 7, you could determine which URLs should be compressed based on the results of the IsFrequentlyHit method.

By default, the determining factor for a return value of true is two requests in a 10-second time span. You can configure this behavior by modifying the frequentHitThreshold and frequentHitTimePeriod attributes of the <serverRuntime> element in your ApplicationHost.config file. For example, to configure your server to return a value of true when a URL has been requested 10 times in a 5-second period, you would modify the <serverRuntime> element in your ApplicationHost.config file by adding the following attributes:

<serverRuntime
    frequentHitThreshold="10"
    frequentHitTimePeriod="00:00:05" />

The following code example demonstrates how to use the IHttpContext::GetUrlInfo method to create an HTTP module that retrieves an IHttpUrlInfo interface for the current request. Then the example calls the IsFrequentlyHit method to determine whether the URL is requested frequently. Finally, the example displays this information to a Web client.

#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 );

        // Retrieve an IHttpUrlInfo pointer.
        IHttpUrlInfo * pHttpUrlInfo = pHttpContext->GetUrlInfo();

        // Test for an error.
        if (NULL != pHttpUrlInfo)
        {
            // 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 the status information.
            WriteResponseMessage(pHttpContext,"Frequently Hit: ",
                pHttpUrlInfo->IsFrequentlyHit() ? "Yes" : "No" );

            // Return processing to the pipeline.
            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,
        RQ_BEGIN_REQUEST,
        0
    );
}


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.

Type

Description

Client

  • IIS 7.0 on Windows Vista

  • IIS 7.5 on Windows 7

  • IIS Express 7.5 on Windows XP, Windows Vista, Windows 7

  • IIS 8.0 on Windows 8 Client

Server

  • IIS 7.0 on Windows Server 2008

  • IIS 7.5 on Windows Server 2008 R2

  • IIS Express 7.5 on Windows Server 2003, Windows Server 2008, Windows Server 2008 R2

  • IIS 8.0 on Windows Server 2012

Product

IIS 7.0, IIS 7.5, IIS Express 7.5, IIS 8.0

Header

Httpserv.h

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