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Resource Presence

Presence is “active” or “advertisement” discovery. It happens at device level. Although application triggers the operation, it is the stack that sends the notification. It operates in server/client model. Server notifies its presence and the client to subscribe to/unsubscribe from a device's presence events. The resource to enable discovery is hosted local to the client who initiates the discovery request. The publishing device (server) is responsible for the published information.

Call Flow

  • (1) OCPlatform::startPresence(30)
  • (2) OCStartPresence(30)
  • (3) Presence Notification
  • (4) OCPlatform::subscribePresence(presenceHandle, hostAddress, connectivityType, presenceHandler)
  • (5) OCDoResource(ocdoHandle, OC_REST_PRESENCE,host, resourceTpype, connectivityType, &cbdata, presenceHandler);
  • (6) OCPlatform::registerResource(m_resourceHandle, resourceURI, resourceTypeName, resourceInterface, &entityHandler, resourceProperty);
  • (7) OCDoResource(…)
  • (8) Presence Notification


APIs Functionalities Examples Client/Server API
OCStackResult startPresence(const unsigned int announceDurationSeconds) Start Presence announcements. OCPlatform::startPresence(30) Server
OCStackResult stopPresence() Stop Presence announcements. OCPlatform::stopPresence() Server
OCStackResult subscribePresence(OCPresenceHandle& presenceHandle, const std::string& host, OCConnectivityType connectivityType, SubscribeCallback presenceHandler) subscribe OCPlatform::subscribePresence(presenceHandle, hostAddress, connectivityType, presenceHandle) Client
OCStackResult subscribePresence(OCPresenceHandle& presenceHandle, const std::string& host, const std::string& resourceType, OCConnectivityType connectivityType, SubscribeCallback presenceHandle) subscribe OCPlatform::subscribePresence(presenceHandle, hostaddress, resourceType, connectivityType, presenceHandler) Client
OCStackResult unsubscribePresence(OCPresenceHandle presenceHandle) unsubscribe OCPlatform::unsubscribePresence(presenceHandle) Client

Presence Resource

The presence resource is modelled as a collection with uri of “/oic/ad', and each resource of type “”. Examples of presence resource could be:

    std::array<std::string, numPresenceResources> resourceURI { {
        "/a/led" } };
    std::array<std::string, numPresenceResources> resourceTypeName { {
        "core.led" } };

Sample Application :

Presence samples provides examples to use presence APIs. They are also good examples showing the call flows described above.

  • Sample with basic presence feature for server side: resource/examples/presenceserver.cpp
  • Sample with basic presence feature for client side: resource/examples/presenceclient.cpp

Server side

Server starts presence advertisement with TTL (time to live) in seconds. e.g.


and can stop it by calling


While registering/creating presence resources, server needs to gone through each resource in the collection. e.g.

for(int i=0; i<numPresenceResources; i++)
        result = OCPlatform::registerResource(handle,
      ,, resourceInterface,
                &entityHandler, resourceProperty);
        if (result != OC_STACK_OK)
            cout << "Resource creation was unsuccessful with resource URI "

Client side

Client can choose to subscribe to the presence notification via unicast by giving specific host address, e.g.

OCPlatform::subscribePresence(presenceHandle, hostAddress,
                            connectivityType, &presenceHandler);

or multicast, e.g.

OCPlatform::subscribePresence(presenceHandle, hostAddress,
                            connectivityType, &presenceHandler);

Where presenceHandler is the callback function for presence, e.g.

void presenceHandler(OCStackResult result, const unsigned int nonce, const std::string& hostAddress)
    //function body
resource_presence.txt · Last modified: 2016/07/25 15:52 by Ziran Sun