DdeSetQualityOfService function (dde.h)

Article
10/13/2021

Specifies the quality of service (QOS) a raw Dynamic Data Exchange (DDE) application desires for future DDE conversations it initiates. The specified QOS applies to any conversations started while those settings are in place. A DDE conversation's quality of service lasts for the duration of the conversation; calls to the DdeSetQualityOfService function during a conversation do not affect that conversation's QOS.

Syntax

BOOL DdeSetQualityOfService(
  [in]  HWND                              hwndClient,
  [in]  const SECURITY_QUALITY_OF_SERVICE *pqosNew,
  [out] PSECURITY_QUALITY_OF_SERVICE      pqosPrev
);

Parameters

[in] hwndClient

Type: HWND

A handle to the DDE client window that specifies the source of WM_DDE_INITIATE messages a client will send to start DDE conversations.

[in] pqosNew

Type: const SECURITY_QUALITY_OF_SERVICE*

A pointer to a SECURITY_QUALITY_OF_SERVICE structure for the desired quality of service values.

[out] pqosPrev

Type: PSECURITY_QUALITY_OF_SERVICE

A pointer to a SECURITY_QUALITY_OF_SERVICE structure that receives the previous quality of service values associated with the window identified by hwndClient.

This parameter is optional. If an application has no interest in hwndClient's previous QOS values, it should set pqosPrev to NULL.

Return value

Type: BOOL

If the function succeeds, the return value is nonzero.

If the function fails, the return value is zero. To get extended error information, call GetLastError.

Remarks

If a quality of service has not been specified for a client window, hwndClient, prior to sending a WM_DDE_INITIATE with the wParam set to hwndClient, the system uses the following default quality of service values for the client window:

{ 
   Length = sizeof(SECURITY_QUALITY_OF_SERVICE); 
   ImpersonationLevel = SecurityImpersonation; 
   ContextTrackingMode = SECURITY_STATIC_TRACKING; 
   EffectiveOnly = TRUE; 
}

Use the DdeSetQualityOfService function to associate a different quality of service with the client window. After you change the quality of service, the new settings affect any subsequent conversations that are started. Once an application starts a DDE conversation using a particular quality of service value, it must terminate the conversation and restart the conversation in order to have a different value take effect.

Requirements

Requirement	Value
Minimum supported client	Windows 2000 Professional [desktop apps only]
Minimum supported server	Windows 2000 Server [desktop apps only]
Target Platform	Windows
Header	dde.h (include Windows.h)
Library	User32.lib
DLL	User32.dll