HTTP_TRACE_EVENT Structure

Article
05/20/2022

Contains tracing information returned from trace providers.

Syntax

struct HTTP_TRACE_EVENT{  
   LPCGUID pProviderGuid;  
   DWORD dwArea;  
   LPCGUID pAreaGuid;  
   DWORD dwEvent;  
   LPCWSTR pszEventName;  
   DWORD dwEventVersion;  
   DWORD dwVerbosity;  
   LPCGUID pActivityGuid;  
   LPCGUID pRelatedActivityGuid;  
   DWORD dwTimeStamp;  
   DWORD dwFlags;  
   DWORD cEventItems;  
   __field_ecount(cEventItems) HTTP_TRACE_EVENT_ITEM * pEventItems;  
};

Members

Member name	Description
`pProviderGuid`	An `LPCGUID` that contains the identifier of the provider. Possible values include, but are not limited to, the values in the Tracing GUIDs section defined in Tracing Constants.
`dwArea`	A `DWORD` that contains the area of interest for the event. The area value should be a positive integer.
`pAreaGuid`	A `LPCGUID` that indicates the area of interest.
`dwEvent`	A `DWORD` that contains the unique identifier of the event for the event provider.
`pszEventName`	A `LPCWSTR` that contains the name of the event. This value is set by the event provider to give a description of the event type.
`dwEventVersion`	A `DWORD` that contains the event version. Usually 0 or 1, but can contain any nonnegative integer value.
`dwVerbosity`	A `DWORD` that maps numerical values to their verbose counterparts (the values 0 through 5 map to General, FatalError, Error, Warning, Info, and Verbose).
`pActivityGuid`	A `LPCGUID` that contains the unique request identifier.
`pRelatedActivityGuid`	A `LPCGUID` that contains a value for associating related activities. Most providers set this value to NULL and then allow IIS to populate the value before sending the event to event listeners.
`dwTimeStamp`	A `DWORD` that contains the optional time stamp, represented by an internal tick count.
`dwFlags`	A `DWORD` that contains additional flags. Most providers set this value to HTTP_TRACE_EVENT_FLAG_STATIC_DESCRIPTIVE_FIELDS, described in the Tracing Constants section defined in Tracing Constants.
`cEventItems`	A `DWORD` that contains the number of elements in the `pEventItems` array.
`pEventItems`	An array of HTTP_TRACE_EVENT_ITEM Structure structures of length `cEventItems`.

Remarks

Most of the members of the HTTP_TRACE_EVENT structure map directly to Event Tracing for Windows (ETW) events. The dwArea and pAreaGuid members are unique to IIS.

CGlobalModule derived classes that register for GL_TRACE_EVENT event types receive an IGlobalTraceEventProvider pointer as a parameter on the CGlobalModule::OnGlobalTraceEvent pure virtual method. You can then retrieve an HTTP_TRACE_EVENT pointer by calling the IGlobalTraceEventProvider::GetTraceEvent method, for which you supply a pointer to the address of a NULL HTTP_TRACE_EVENT structure.

For more information, see Tracing Constants.

The dwArea and pAreaGuid members contain two different constants for the area of interest for an event.

Example

The following example populates the HTTP_TRACE_EVENT structure and calls the IHttpTraceContext::RaiseTraceEvent method.

REQUEST_NOTIFICATION_STATUS
CMyHttpModule::OnBeginRequest(
    IHttpContext*       pHttpContext,
    IHttpEventProvider* pProvider
)
{
    HRESULT hr;

    static long cnt;
    InterlockedIncrement(&cnt);  // keep track of how many times we are called
    cnt++;

    IHttpRequest *pRequest = pHttpContext->GetRequest();
    PCWSTR url = pRequest->GetRawHttpRequest()->CookedUrl.pAbsPath;
    OutputDebugStringW(url);

    // return unless requesting a HTML file

    if (!wcsstr(url, L".htm"))
        return RQ_NOTIFICATION_CONTINUE;

    IHttpResponse * pHttpResponse = pHttpContext->GetResponse();

    // Return most times so we can still view content
    if ((cnt % 5) || pHttpResponse == NULL)
        return RQ_NOTIFICATION_CONTINUE;

    TRC_MSG_FULL("HTML  cnt = " << cnt);

    static int insertPosCnt;
    int insertPos = ++insertPosCnt % 2 - 1;    // toggle between 0 and -1

    // Use ostringstream to create some dynamic content
    std::ostringstream os;

    os << "<p /> first chunk  callback count = " << cnt
        << " insertPos = " << insertPos << "<br />";

    // 
    // WECbyRefChunk does all the work of inserting data into the response
    //

    hr = WECbyRefChunk(os, pHttpContext, pProvider, insertPos);
    if (FAILED(hr))
        return RQ_NOTIFICATION_FINISH_REQUEST;

    os << "<br /> <b> Adding 2nd chunk in Bold </b> File insertPos = " << insertPos;
    hr = WECbyRefChunk(os, pHttpContext, pProvider, insertPos);
    if (FAILED(hr))
        return RQ_NOTIFICATION_FINISH_REQUEST;

    os << " <p /> Last (3rd) Chunk added with default append chunk  GetCurrentThreadId = "
        << GetCurrentThreadId();

    // any errors will be logged/handled in  WECbyRefChunk
    WECbyRefChunk(os, pHttpContext, pProvider);

    // End additional processing, not because of error, but so another request
    // (from a GIF or .css style sheet on the same HTML page)
    // doesn't wipe out our WriteEntityChunkByReference. We can also get the
    // WriteEntityChunkByReference prepended to our normal HTML page. 

    return RQ_NOTIFICATION_FINISH_REQUEST;

}


class My_Events
{
public:
    static	LPCGUID	GetAreaGuid( VOID ){ //  GUID for the event class
        static const GUID AreaGuid = 
        {0xacade3b2,0xb7d7,0x4339,{0x95,0x6c,0x81,0x1b,0x4e,0xdb,0x1b,0x24}};
        return &AreaGuid;
    };

    static	LPCGUID	GetProviderGuid( VOID ){ // GUID for the event Provider
        static const GUID PrvderGuid = 
        // {EB881638-214A-4f2a-9B39-933770822D18}
    { 0xeb881638, 0x214a, 0x4f2a, { 0x9b, 0x39, 0x93, 0x37, 0x70, 0x82, 0x2d, 0x18 } };
;
        return &PrvderGuid;
    };


    class My_COMPLETION
    {
    public:
        static	HRESULT	RaiseEvent(
            IHttpTraceContext * pHttpTraceContext,
            LONG InsertPosition
            )
            //
            // Raise Cmy_COMPLETION Event
            //
        {
            HTTP_TRACE_EVENT Event;
            Event.pProviderGuid = My_Events::GetProviderGuid();
            Event.dwArea = 1;
            Event.pAreaGuid = My_Events::GetAreaGuid();
            Event.dwEvent = 1;
            Event.pszEventName = L"NOTIFY_MY_CSTM_WECBR_EVNT";
            Event.dwEventVersion = 2;
            Event.dwVerbosity = 1;
            Event.cEventItems = 1;
            Event.pActivityGuid = NULL;
            Event.pRelatedActivityGuid = NULL;
            Event.dwTimeStamp = 0;
            Event.dwFlags = HTTP_TRACE_EVENT_FLAG_STATIC_DESCRIPTIVE_FIELDS;

            // pActivityGuid, pRelatedActivityGuid, Timestamp to be filled in by IIS

            HTTP_TRACE_EVENT_ITEM Items[ 1 ];
            Items[ 0 ].pszName = L"InsertPosition";
            Items[ 0 ].dwDataType = HTTP_TRACE_TYPE_LONG; // mof type (object)
#pragma warning (disable:4312)
            Items[ 0 ].pbData = (PBYTE) InsertPosition;
            Items[ 0 ].cbData = 4;
            Items[ 0 ].pszDataDescription = L"Insert Position";
            Event.pEventItems = Items;
            return pHttpTraceContext->RaiseTraceEvent( &Event );
        };

    };
};

If failed-request tracing is properly configured, you will see the NOTIFY_MODULE_START and NOTIFY_MODULE_END events in the trace log. For more information about logging failed requests, see Configuring Tracing for Failed Requests in IIS 7.0. The XML below is the NOTIFY_MODULE_START portion of the Failed Request Tracing log. Most of the data is system dependent and will not match the event below.

   <Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">  
 <System>  
  <Provider Name="WWW Server" Guid="{3A2A4E84-4C21-4981-AE10-3FDA0D9B0F83}"/>  
  <EventID>0</EventID>  
  <Version>1</Version>  
  <Level>5</Level>  
  <Opcode>1</Opcode>  
  <Keywords>0x100</Keywords>  
  <TimeCreated SystemTime="2007-08-27T21:10:30.186Z"/>  
  <Correlation ActivityID="{00000000-0000-0000-9800-0080000000FA}"/>  
  <Execution ProcessID="1308" ThreadID="3608"/>  
  <Computer>N2-IIS</Computer>  
 </System>  
 <EventData>  
  <Data Name="ContextId">{00000000-0000-0000-9800-0080000000FA}</Data>  
  <Data Name="ModuleName">A_raizeEvent</Data>  
  <Data Name="Notification">1</Data>  
  <Data Name="fIsPostNotification">false</Data>  
  <Data Name="fIsCompletion">false</Data>  
 </EventData>  
 <RenderingInfo Culture="en-US">  
  <Opcode>NOTIFY_MODULE_START</Opcode>  
  <Keywords>  
   <Keyword>RequestNotifications</Keyword>  
  </Keywords>  
  <freb:Description Data="Notification">BEGIN_REQUEST</freb:Description>  
 </RenderingInfo>  
 <ExtendedTracingInfo xmlns="http://schemas.microsoft.com/win/2004/08/events/trace">  
  <EventGuid>{002E91E3-E7AE-44AB-8E07-99230FFA6ADE}</EventGuid>  
 </ExtendedTracingInfo>  
</Event>

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
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	Httptrace.h

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HTTP_TRACE_EVENT Structure

Syntax

Members

Remarks

Example

Requirements

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