Presence API for Kotlin SDK

Breaking changes in v9.0.0

PubNub Kotlin SDK version 9.0.0 unifies the codebases for Kotlin and Java SDKs, introduces a new way of instantiating the PubNub client, and changes asynchronous API callbacks and emitted status events. These changes can impact applications built with previous versions (< 9.0.0 ) of the Kotlin SDK.

For more details about what has changed, refer to Java/Kotlin SDK migration guide.

Presence lets you track who is online or offline and store custom state information. Presence shows:

• When a user has joined or left a channel
• How many users are subscribed to a particular channel (occupancy)
• Which channels a user or device is subscribed to
• Presence state associated with these users

Learn more about our Presence feature in the Presence overview.

Request execution

Most PubNub Kotlin SDK method invocations return an Endpoint object, which allows you to decide whether to perform the operation synchronously or asynchronously.

You must invoke the .sync() or .async() method on the Endpoint to execute the request, or the operation will not be performed.

val channel = pubnub.channel("channelName")

channel.publish("This SDK rules!").async { result ->
    result.onFailure { exception ->
        // Handle error
    }.onSuccess { value ->
        // Handle successful method result
    }
}

Here now

Requires Presence

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

For information on how to receive presence events and what those events are, refer to Presence Events.

This method returns information about the current state of a channel, including a list of unique user IDs (universally unique identifiers, UUIDs) currently subscribed to the channel and the total occupancy count of the channel.

Cache

This method has a 3-second response cache time.

Method(s)

To call Here Now you can use the following methods in the Kotlin SDK:

pubnub.hereNow(
    channels: List<String>,
    channelGroups: List<String>,
    includeState: Boolean,
    includeUUIDs: Boolean
).async { result -> }

* required

Parameter	Description
channels Type: List<String> Default: n/a	The channels to get the 'here now' details of.
channelGroups Type: List<String> Default: n/a	The channelGroups to get the 'here now' details of. Wildcards are not supported.
includeState Type: Boolean Default: false	If true, the response will include the presence states of the users for channels/channelGroups.
includeUUIDs Type: Boolean Default: true	If true, the response will include the UUIDs of the connected clients.

Sample code

Reference code

This example is a self-contained code snippet ready to be run. It includes necessary imports and executes methods with console logging. Use it as a reference when working with other examples in this document.

Get a list of UUIDs subscribed to channel

Returns

The hereNow() operation returns a PNHereNowResult? which contains the following operations:

Method	Description
totalChannels Type: Int	Total channels
totalOccupancy Type: Int	Total occupancy
channels Type: Map<String, PNHereNowChannelData>	A map with values of PNHereNowChannelData for each channel. See PNHereNowChannelData for more details.

PNHereNowChannelData

Method	Description
channelName Type: String	Channel name
occupancy Type: Int	Occupancy of the channel
occupants Type: List<PNHereNowOccupantData>	A list of PNHereNowOccupantData, see PNHereNowOccupantData for more details.

PNHereNowOccupantData

Method	Description
uuid Type: String	UUID of the user
state Type: JsonElement?	State of the user

Other examples

Returning state

Requires Presence

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

For information on how to receive presence events and what those events are, refer to Presence Events.

Example response:

.async { result: Result<PNHereNowResult> ->
    result.onSuccess { res: PNHereNowResult ->
        res.channels.values.forEach { channelData ->
            channelData.channelName // ch1
            channelData.occupancy // 3
            channelData.occupants.forEach { o ->
                o.uuid // some_uuid, returned by default
                o.state // {"data":{"isTyping":true}}, requested
            }
        }
    }.onFailure { e ->
        // handle error
        e.message
        e.statusCode
        e.pubnubError

show all 17 lines

Return occupancy only

Requires Presence

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

For information on how to receive presence events and what those events are, refer to Presence Events.

You can return only the occupancy information for a single channel by specifying the channel and setting UUIDs to false:

Example response:

.async { result: Result<PNHereNowResult> ->
    result.onSuccess { res: PNHereNowResult ->
        res.channels.values.forEach { channelData ->
            channelData.channelName // ch1
            channelData.occupancy // 3
        }
    }.onFailure { e ->
        // handle error
        e.message
        e.statusCode
        e.pubnubError
    }
}

Here now for channel groups

Example response:

.async { result: Result<PNHereNowResult> ->
    result.onSuccess { res: PNHereNowResult ->
        res.totalOccupancy
    }.onFailure { e ->
        // handle error
        e.message
        e.statusCode
        e.pubnubError
    }
}

Where now

Requires Presence

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

For information on how to receive presence events and what those events are, refer to Presence Events.

This method returns the list of channels a UUID is subscribed to.

Timeout events

If the app restarts (or the page refreshes) within the heartbeat window, no timeout event is generated.

Method(s)

To call whereNow() you can use the following method(s) in the Kotlin SDK:

pubnub.whereNow(
    uuid: String
).async { result -> }

* required

Parameter	Description
uuid Type: String Default: n/a	UUID of the user to get its current channel subscriptions.

Sample code

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

Returns

The whereNow() operation returns a PNWhereNowResult? which contains the following operations:

Method	Description
channels Type: List<String>	List of channels where the uuid is present.

Other examples

Obtain information about the current list of channels of some other UUID

User state

Requires Presence

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

For information on how to receive presence events and what those events are, refer to Presence Events.

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.

Presence state format

Presence state must be expressed as a JsonObject. When calling setState, be sure to supply an initialized JsonObject or POJO which can be serialized to a JsonObject.

Method(s)

To set the state, call setPresenceState() you can use the following method(s) in the Kotlin SDK:

Set state

pubnub.setPresenceState(
    channels: List<String>,
    channelGroups: List<String>,
    state: Any,
    uuid: String
).async { result -> }

* required

Parameter	Description
channels Type: List<String> Default: n/a	Channels to set state to.
channelGroups Type: List<String> Default: n/a	Channel groups to set state to.
state Type: Any Default: n/a	The state to set.
uuid Type: String Default: n/a	The UUID to set state for.

Get state

pubnub.getPresenceState(
    channels: List<String>,
    channelGroups: List<String>,
    uuid: String
).async { result -> }

To get the state, call getPresenceState() you can use the following method(s) in the Kotlin SDK:

* required

Parameter	Description
channels Type: List<String> Default: n/a	Channels to get state of.
channelGroups Type: List<String> Default: n/a	Channel groups to get state of.
uuid Type: String Default: n/a	The UUID to get state for.

Sample code

Returns

The setPresenceState() operation returns a PNSetStateResult? which contains the following operations:

Method	Description
state Type: JsonElement	The actual state object

The getPresenceState() operation returns a PNSetStateResult? which contains the following operations:

Method	Description
stateByUUID Type: Map<String, JsonElement>	Map of UUIDs and the user states.

Other examples

Set state for channels in channel group

Get state for UUID