Synchronous Searching

The Device Finder object enables both synchronous and asynchronous searches. Synchronous searches are completed and return control to the calling application only after all available devices are found. To perform a synchronous search, use one of the synchronous search methods of the IUPnPDeviceFinder interface.

The IUPnPDeviceFinder::FindByType method searches by device or service type. This method takes a type URI as an input parameter and returns a collection of Device objects. A Device object represents an individual device.

The following examples demonstrate how to perform a synchronous search for devices in VBScript. Each script uses IUPnPDeviceFinder::FindByType, called with the type URI (service ID) for the media player device type, urn:schemas-upnp-org:device:mediaplayer.v1.00.00. The method returns a collection of Device objects that corresponds to media player devices that were found. For information on extracting individual device objects from a collection, see Device Collections Returned By Synchronous Searches.

Search for Devices by Type in VBScript

Dim deviceFinder

Set deviceFinder = CreateObject( "UPnP.UPnPDeviceFinder" )

Dim devices

Set devices = deviceFinder.FindByType( "urn:schemas-upnp-org:device:multidisk-dvd", 0 )

Search for Device by Type in C++

The following example demonstrates a synchronous search for media player devices using C++. The function takes a pointer to the IUPnPDeviceFinder interface as input, and returns the IUPnPDevices interface pointer.

The example first allocates a BSTR to represent the device type URI and then passes this to the IUPnPDeviceFinder::FindByType method. It also passes the address of a local IUPnPDevices pointer in the buffer in which the method then stores the collection of devices found. If the function call is successful, it returns the pointer to this collection.

#include <windows.h>
#include <upnp.h>
#include <stdio.h>

#pragma comment(lib, "oleaut32.lib")

IUPnPDevices *FindMediaPlayerDevices(IUPnPDeviceFinder *pDeviceFinder)
{
    HRESULT         hr = S_OK;
    IUPnPDevices    * pFoundDevices = NULL;
    BSTR            bstrTypeURI = NULL;

    bstrTypeURI = 
        SysAllocString(L"urn:schemas-upnp-org:device:multidisk-dvd");

    if (bstrTypeURI)
    {
        hr = pDeviceFinder->FindByType(bstrTypeURI, 
                                       0,
                                       &pFoundDevices);

        if (SUCCEEDED(hr))
        {
            wprintf(L"FindMediaPlayerDevices(): "
                    L"Search returned successfully\n");
        }
        else
        {
            fwprintf(stderr, L"FindMediaPlayerDevices(): "
                     L"FindByType search failed - returned "
                     L"HRESULT 0x%x\n",
                     hr);
            pFoundDevices = NULL;
        }
        SysFreeString(bstrTypeURI);
    }
    else
    {
        fwprintf(stderr, L"FindMediaPlayerDevices(): "
                 L"Could not allocate BSTR for type URI\n");
    }

    return pFoundDevices;
}