QOSStartTrackingClient function (qos2.h)
The QOSStartTrackingClient function notifies the QOS subsystem of the existence of a new client. Calling this function increases the likelihood that the QOS subsystem will have gathered sufficient information on the network path to assist when calling QOSSetFlow to set the flow.
Syntax
ExternC BOOL QOSStartTrackingClient(
[in] HANDLE QOSHandle,
[in] PSOCKADDR DestAddr,
DWORD Flags
);
Parameters
[in] QOSHandle
Handle to the QOS subsystem returned by QOSCreateHandle.
[in] DestAddr
A pointer to a sockaddr structure that contains the IP address of the client device. Clients are identified by their IP address and address family. Any port number specified in the sockaddr structure will be ignored.
Flags
Reserved for future use. Must be set to 0.
Return value
If the function succeeds, the return value is nonzero.
If the function fails, the return value is 0. To get extended error information, call GetLastError. Some possible error codes follow.
Return code | Description |
---|---|
|
The QOSHandle parameter is invalid. |
|
The DestAddr parameter is invalid. |
|
Indicates that a memory allocation failed. |
|
There are insufficient resources to carry out the operation. |
|
The request could not be performed because of an I/O device error. |
|
The indicated device requires reinitialization due to hardware errors. The application should clean up and call QOSCreateHandle again. |
|
The request is not supported. |
|
A network adapter hardware error occurred. |
|
The network location cannot be reached. |
Remarks
On receipt of a QOSStartTrackingClient call the QoS subsystem begins gathering information about the client such as the QoS capabilities and available bandwidth on the end-to-end path.
An application should call this function as soon as it becomes aware of a client device that may need QoS flow. For example this function should be called when a media player device first connects to a media server application.
Network experiments performed by QOSStartTrackingClient do not introduce noteworthy load on the network even if no stream is started for a long period of time. The qWAVE service dynamically adjusts experiment traffic based on QoS subsystem activity.
Link Layer Topology Discovery (LLTD) must be implemented on the sink PC or device for this function to work.
Examples
The following code illustrates function use, handling a common exception, and required parameter initializations. Actual parameter values can vary depending on QoS version. The Winsock2.h header file must be included to use Winsock defined identifiers or functions.
QOS_VERSION Version;
HANDLE QoSHandle = NULL;
BOOL QoSResult = FALSE;
Version.MajorVersion = 1;
Version.MinorVersion = 0;
// Get a handle to the QoS subsystem (required for tracking).
QoSResult = QOSCreateHandle(
&Version,
&QoSHandle );
if(!QOSStartTrackingClient(QoSHandle, (sockaddr*)ptr->ai_addr, 0))
{
std::cerr << std::endl;
std::cerr << __FILE__ <<" Line: " << __LINE__ ;
std::cerr << " - QOSStartTrackingClient failed. Exception code: ";
std::cerr << GetLastError();
if (GetLastError() == ERROR_NOT_SUPPORTED)
{
std::cerr << std::endl;
std::cerr << " ERROR_NOT_SUPPORTED" << std::endl;
std::cerr << "This operation requires information";
std::cerr << "that the QoS subsystem does not have. " << std::endl;
}
}
else
std::cout << "QoS client tracking started." << std::endl;
Requirements
Requirement | Value |
---|---|
Minimum supported client | Windows Vista [desktop apps only] |
Minimum supported server | Windows Server 2008 [desktop apps only] |
Target Platform | Windows |
Header | qos2.h (include Qos2.h) |
Library | Qwave.lib |
DLL | Qwave.dll |
See also
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