Presence API for Windows C++ SDK

Presence enables you to track the online and offline status of users and devices in real time, as well as store custom state information. Presence provides authoritative information on:

• When a user has joined or left a channel
• Who, and how many, users are subscribed to a particular channel
• Which channel(s) an individual user is subscribed to
• Associated state information for these users

Learn more about our Presence feature here.

Here Now

Requires Presence

This method requires that the Presence add-on is enabled for your key in the Admin Portal.

You can obtain information about the current state of a channel including a list of unique user-ids currently subscribed to the channel and the total occupancy count of the channel by calling the here_now() function in your application.

Cache

This method has a 3 second response cache time.

Method(s)

To call Here Now you can use the following method(s) in the Windows C++ SDK:

here_now (std::string const &channel, std::string const &channel_group="")

* required

Parameter	Description
channel * Type: std::string const &	Specifies channel for which to return active uuids.
channel_group Type: std::string const &	Specifies channel_group for which to return active uuids.

here_now (std::vector<std::string> const &channel, std::vector<std::string> const &channel_group)

* required

Parameter	Description
channel * Type: std::string const &	Specifies channel vector for which to return active uuids.
channel_group * Type: std::string const &	Specifies channel_group vector for which to return active uuids.

Basic Usage

Get a list of uuids subscribed to channel

// Sync
void here_now(pubnub::context &pn) {
  enum pubnub_res res;

  res = pn.here_now("my_channel").await();

  if (PNR_OK == res) {
    std::cout << pn.get() << std::endl;
  } else {
    std::cout << "Here Now request failed" << std::endl;
  }
}

// Lambdas
void here_now(pubnub::context &pn) {

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Rest Response from Server

The here_now() function returns a list of uuids currently subscribed to the channel.

• uuids:["String","String", ... ,"String"] - List of UUIDs currently subscribed to the channel.
• occupancy: Number - Total current occupancy of the channel.

{
  "occupancy" : 4,
  "uuids" : "['123123234t234f34fq3dq', '143r34f34t34fq34q34q3', '23f34d3f4rq34r34rq23q', 'w34tcw45t45tcw435tww3']"
}

Where Now

Requires Presence

This method requires that the Presence add-on is enabled for your key in the Admin Portal.

You can obtain information about the current list of channels to which a UUID is subscribed to by calling the where_now() function in your application.

Timeout events

If the app is killed/crashes and restarted (or the page containing the PubNub instance is refreshed on the browser) within the heartbeat window no timeout event is generated.

Method(s)

To call where_now() you can use the following method(s) in the Windows C++ SDK:

where_now (std::string const &uuid="")

* required

Parameter	Description
uuid * Type: std::string const &	Specifies uuid for which current subscribed channels info is required

Basic Usage

You simply need to define the uuid and the callback function to be used to send the data to as in the example below.

Get a list of channels a UUID is subscribed to

//Sync
static void where_now(pubnub::context &pn) {
  enum pubnub_res res;

  try {
    res = pn.where_now("my_uuid").await();

    if (PNR_OK == res) {
      std::cout <<  pn.get() << std::endl;
    } else {
      std::cout << "Failed with code " << res << std::endl;
    }
  } catch (std::exception &ex) {
    std::cout << "Exception: " << ex.what() << std::endl;
  }

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Rest Response from Server

The where_now() function returns a list of channels a uuid is subscribed to.

• channels:["String","String", ... ,"String"] - List of channels a uuid is subscribed to.

Example Response

{
    "channels": [
        "lobby",
        "game01",
        "chat"
    ]
}

User State

Requires Presence

This method requires that the Presence add-on is enabled for your key in the Admin Portal.

Clients can set a dynamic custom state (score, game state, location) for their users on one or more channels and store it on a channel as long as the user stays subscribed.

The state is not persisted, and when the client disconnects, the state data is lost. For more information, refer to Presence State.

Method(s)

Set State

set_state (std::string const &channel, std::string const &channel_group, std::string const &uuid, std::string const &state)

* required

Parameter	Description
channel * Type: std::string const &	Channel to set state on
channel_group * Type: std::string const &	Channel_group to set state on
uuid * Type: std::string const &	UUID
state * Type: std::string const &	Serialized JSON state

Set State with Options

set_state (std::string const &channel, const &state, set_state_options options )

* required

Parameter	Description
channel * Type: std::string const &	Channel to set state on
state * Type: std::string const &	Serialized JSON state
options * Type: set_state_options	Extra options for this call. Refer to the section below for more information.

set_state_options

* required

Parameter	Description
channel_group Type: std::string	The string with the channel name (or comma-delimited list of channel group names) to set state for.
user_id * Type: std::string	The user_id of the user for which to set state for. If NULL, the current user_id is used.
heartbeat * Type: bool	If set to true, you can set the state and make a heartbeat call at the same time via the /heartbeat endpoint.

Get State

state_get (std::string const &channel, std::string const &channel_group="", std::string const &uuid="")

* required

Parameter	Description
channel * Type: std::string const &	Channel to get state.
channel_group Type: std::string const &	Channel group to get the state.
uuid Type: std::string const &	UUID

Basic Usage

Set State

static void set_state(pubnub::context &pn) {
  enum pubnub_res res;

  try {
    std::string state("{\"first\":\"Robert\", \"last\":\"Plant\", \"age\":59, \"region\":\"UK\"}");
    res = pn.set_state("my_channel", "", "my_uuid", state).await();

    if (PNR_OK == res) {
      std::cout <<  pn.get() << std::endl;
    } else {
      std::cout << "Failed with code " << res << std::endl;
    }
  } catch (std::exception &ex) {
    std::cout << "Exception: " << ex.what() << std::endl;
  }

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Set State with Heartbeat

std::cout << "Setting state with options" << std::endl;
  if (PNR_OK ==  pb.set_state(
      chan, "{\"x\":5}", pubnub::set_state_options().heartbeat(true)
    ).await()) {
      std::cout << "State was set: " << pb.get() << std::endl;
    }
    else {
        std::cout << "Setting state failed!" << std::endl;
    }

Get State

static void get_state(pubnub::context &pn) {
  enum pubnub_res res;

  try {
    res = pn.state_get("my_channel", "", "my_uuid").await();

    if (PNR_OK == res) {
      std::cout <<  pn.get() << std::endl;
    } else {
      std::cout << "Failed with code " << res << std::endl;
    }
  } catch (std::exception &ex) {
    std::cout << "Exception: " << ex.what() << std::endl;
  }
}

Returns

The state API returns a JSON object containing key value pairs.

{
    first   : "Robert",
    last    : "Plant",
    age     : 59,
    region  : "UK"
}

Heartbeat

Requires Presence

This method requires that the Presence add-on is enabled for your key in the Admin Portal.

This method notifies channels and channel groups about a client's presence. You can send heartbeats to channels you are not subscribed to.

Method(s)

pb.heartbeat(std::string const& channel, std::string const& channel_group)

* required

Parameter	Description
channel Type: std::string const&	The string with the channel name (or comma-delimited list of channel names) to notify.
channel_group Type: std::string const&	The string with the channel_group name (or comma-delimited list of channel group names) to notify.

Basic Usage

res = pb.heartbeat(chan, NULL).await();
if (PNR_OK == res) {
    puts("Heartbeated! Got messages:");
}
else {
    printf("Heartbeating failed with code: %d('%s')\n",
            res,
            pubnub_res_2_string(res));
}

Returns

This method returns a PubNub result enum or an error, depending on the status of the transaction.