Presence API for PubNub 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 add-on

This method requires that the Presence add-on is enabled for your key in the Admin Portal. Read the support page on enabling add-on features on your keys.

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 pubnub_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:

enum pubnub_res pubnub_here_now (pubnub_t *p, const char *channel, const char *channel_group)

Parameter	Type	Required	Description
`p`	pubnub_t*	Yes	Pointer to Pubnub client context.
`channel`	const char*	Optional	The `string` with the `channel` name (or comma-delimited list of `channel` names) to get `presence` info for.
`channel_group`	const char*	Optional	The `string` with the `channel` name (or comma-delimited list of channel `group` names) to get `presence` info for.

Basic Usage

Get a list of uuids subscribed to channel

// Sync

pubnub_here_now(ctx, "my_channel", NULL);
pbresult = pubnub_await(ctx);
if (PNR_OK == pbresult) {
    char const *json_response = pubnub_get(ctx);
}

//callback

int here_now(pubnub_t *pn) {
  char const *chan = "my_channel";
  char const *msg;
  enum pubnub_res res;

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Rest Response from Server

The pubnub_here_now() function returns a list of uuid s 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 add-on

This method requires that the Presence add-on is enabled for your key in the Admin Portal. Read the support page on enabling add-on features on your keys.

You can obtain information about the current list of channels to which a UUID is subscribed to by calling the pubnub_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 pubnub_where_now() you can use the following method(s) in the Windows C SDK:

enum pubnub_res pubnub_where_now (pubnub_t *p, const char *uuid)

Parameter	Type	Required	Description
`p`	pubnub_t*	Yes	Pointer to Pubnub client context.
`uuid`	const char*	Optional	The `UUID` of the user to get the `channel` presence. If `NULL`, the current `UUID` of the `p` context will be used.

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

char const *msg;
enum pubnub_res res;

res = pubnub_where_now(pn, "my_uuid");
if (res != PNR_STARTED) {
  printf("pubnub_where_now() returned unexpected: %d\n", res);
  return -1;
}

res = pubnub_await(pn);

if (res == PNR_STARTED) {
  printf("pubnub_await() returned unexpected: PNR_STARTED(%d)\n", res);
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Rest Response from Server

The pubnub_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 add-on

This method requires that the Presence add-on is enabled for your key in the Admin Portal. Read the support page on enabling add-on features on your keys.

The state API is used to set/get key/value pairs specific to a subscriber uuid.

State information is supplied as a JSON object of key/value pairs.

Method(s)

Set State

enum pubnub_res pubnub_set_state (pubnub_t *p, char const *channel, char const *channel_group, const char *uuid, char const *state)

Parameter	Type	Required	Description
`p`	pubnub_t*	Yes	Pointer to Pubnub client context.
`channel`	char const*	Optional	The `string` with the `channel` name (or comma-delimited list of `channel` names) to set `state` for.
`channel_group`	char const*	Optional	The `string` with the `channel` name (or comma-delimited list of channel `group` names) to set `state` for.
`uuid`	const char*	Yes	The `UUID` of the user for which to set `state` for. If `NULL`, the current `UUID` of the `p` context will be used.
`state`	char const*	Yes	Has to be a JSON object

Get State

enum pubnub_res pubnub_state_get (pubnub_t *p, char const *channel, char const *channel_group, const char *uuid)

Parameter	Type	Required	Description
`p`	pubnub_t*	Yes	Pointer to Pubnub Client Context
`channel`	char const*	Optional	The string with the `channel` name (or comma-delimited list of channel names) to get the state for.
`channel_group`	char const*	Optional	The string with the `channel` name (or comma-delimited list of `channel group` names) to get the `state` for.
`uuid`	const char*	Optional	The `UUID` of the user for which to get the `state` for. If NULL, the current `UUID` of the `p` context will be used.

Basic Usage

Set State

pubnub_set_state(ctx, "hello_world", NULL, NULL, NULL);
pbresult = pubnub_await(ctx);
if (PNR_OK == pbresult) {
    printf("Set success\n");
}

Get State

pubnub_get_state(ctx, "my_channel", NULL, NULL);
pbresult = pubnub_await(ctx);
if (PNR_OK == pbresult) {
    char const *json_response = pubnub_get(ctx);
}

Returns

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

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

Extended Set State

Requires Presence add-on

This method requires that the Presence add-on is enabled for your key in the Admin Portal. Read the support page on enabling add-on features on your keys.

Extended Set State Options structure

Parameter	Type	Required	Description
`p`	`pubnub_t*`	Yes	Pointer to PubNub client context.
`channel_group`	`char const*`	Optional	The `string` with the `channel` name (or comma-delimited list of channel `group` names) to set `state` for.
`user_id`	`const char*`	Yes	The `user_id` of the user for which to set `state` for. If `NULL`, the current `user_id` of the `p` context will be used.
`heartbeat`	`bool`	Yes	If set to `true`, you can set the state and make a heartbeat call at the same time via the `/heartbeat` endpoint.

Description

The extended state API is used to set/get key/value pairs specific to a subscriber user_id with extra options.

State information is supplied as a JSON object of key/value pairs.

Method(s)

Set State with options

enum pubnub_res pubnub_set_state_ex(pubnub_t* p, 
  const char* channel, 
  const char* state, 
  struct pubnub_set_state_options opts);

Parameter	Type	Required	Description
`p`	`pubnub_t*`	Yes	Pointer to PubNub client context.
`channel`	`char const*`	Optional	The `string` with the `channel` name (or comma-delimited list of `channel` names) to set `state` for.
`state`	`char const*`	Yes	Has to be a JSON object.
`opts`	`pubnub_set_state_options`	Yes	Refer to Extended set state options structure.

Basic Usage

Set State with Heartbeat

struct pubnub_set_state_options opt = pubnub_set_state_defopts();
opt.heartbeat = true;
pbresult = pubnub_set_state_ex(pn, "my_channel", "{}", opt);

Returns

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

The state API returns the result of the transaction.

State was set: {"status": 200, "message": "OK", "service": "Presence"}

Heartbeat

Requires Presence add-on

This method requires that the Presence add-on is enabled for your key in the Admin Portal. Read the support page on enabling add-on features on your keys.

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)

enum pubnub_res pubnub_heartbeat(pubnub_t*   pb, const char* channel, const char* channel_group)

Parameter	Type	Required	Description
`pb`	`pubnub_t*`	Yes	Pointer to PubNub client context.
`channel`	`char const*`	Optional	The `string` with the `channel` name (or comma-delimited list of `channel` names) to notify.
`channel_group`	`char const*`	Optional	The `string` with the `channel_group` name (or comma-delimited list of channel `group` names) to notify.

Basic Usage

res = pubnub_heartbeat(pbp, chan, NULL);
if (PNR_STARTED == res) {
    res = pubnub_await(pbp);
}
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.

Here Now​

Requires Presence add-on

Cache

Method(s)​

Basic Usage​

Get a list of uuids subscribed to channel​

Rest Response from Server​

Where Now​

Requires Presence add-on

Timeout events

Method(s)​

Basic Usage​

Get a list of channels a UUID is subscribed to​

Rest Response from Server​

Example Response​

User State​

Requires Presence add-on

Method(s)​

Set State​

Get State​

Basic Usage​

Set State​

Get State​

Returns​

Extended Set State​

Requires Presence add-on

Extended Set State Options structure​

Description​

Method(s)​

Set State with options​

Basic Usage​

Set State with Heartbeat​

Returns​

Heartbeat​

Requires Presence add-on

Method(s)​

Basic Usage​

Returns​

Here Now

Method(s)

Basic Usage

Get a list of uuids subscribed to channel

Rest Response from Server

Where Now

Method(s)

Basic Usage

Get a list of channels a UUID is subscribed to

Rest Response from Server

Example Response

User State

Method(s)

Set State

Get State

Basic Usage

Set State

Get State

Returns

Extended Set State

Extended Set State Options structure

Description

Method(s)

Set State with options

Basic Usage

Set State with Heartbeat

Returns

Heartbeat

Method(s)

Basic Usage

Returns