Presence API for Java SDK

Breaking changes in v9.0.0

PubNub Java SDK version 9.0.0 unifies the codebases for Java and Kotlin 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 Java SDK.

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

Presence enables you to track the online and offline status of users and devices in real time, and 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 hereNow() 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 Java SDK:

this.pubnub.hereNow()
.channels(Array)
.channelGroups(Arrays)
.includeState(true)
.includeUUIDs(true)
* required
ParameterDescription
channels
Type: Array
Default:
n/a
The channels to get the here now details.
channelGroups
Type: Arrays
Default:
n/a
The channelGroups to get the here now details.
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.
async *
Type: Consumer<Result>
Default:
n/a
Consumer of a Result of type PNHereNowResult

Basic Usage

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

import com.pubnub.api.PubNubException;
import com.pubnub.api.java.PubNub;
import com.pubnub.api.java.v2.PNConfiguration;
import com.pubnub.api.UserId;
import com.pubnub.api.enums.PNLogVerbosity;
import com.pubnub.api.models.consumer.presence.PNHereNowChannelData;
import com.pubnub.api.models.consumer.presence.PNHereNowOccupantData;

import java.util.Arrays;

public class HereNowApp {
public static void main(String[] args) throws PubNubException {
// Configure PubNub instance
PNConfiguration.Builder configBuilder = PNConfiguration.builder(new UserId("demoUserId"), "demo");
configBuilder.publishKey("demo");
show all 44 lines

Returns

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

MethodDescription
getTotalChannels()
Type: Int
Total Channels.
getTotalOccupancy()
Type: Int
Total Occupancy.
getChannels()
Type: Map<String, PNHereNowChannelData>
A map with values of PNHereNowChannelData for each channel. See PNHereNowChannelData for more details.

PNHereNowChannelData

MethodDescription
getChannelName()
Type: String
Channel name.
getOccupancy()
Type: Int
Occupancy of the channel.
getOccupants()
Type: List<PNHereNowOccupantData>
A list of PNHereNowOccupantData, see PNHereNowOccupantData for more details.

PNHereNowOccupantData

MethodDescription
getUuid()
Type: String
UUIDs of the user.
getState()
Type: Object
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.

pubnub.hereNow()
.channels(Arrays.asList("my_channel")) // who is present on those channels?
.includeState(true) // include state with request (false by default)
.includeUUIDs(true) // if false, only shows occupancy count
.async(result -> { /* check result */ });
Example Response
.async(result -> {
result.onSuccess(res -> {
// Iterate through channels if the request was successful
for (PNHereNowChannelData channelData : res.getChannels().values()) {
System.out.println("Channel: " + channelData.getChannelName());
System.out.println("Occupancy: " + channelData.getOccupancy());
System.out.println("Occupants:");
for (PNHereNowOccupantData occupant : channelData.getOccupants()) {
System.out.println("UUID: " + occupant.getUuid() + " State: " + occupant.getState());
}
}
}).onFailure((PubNubException exception) -> {
// Handle errors if the request fails
System.err.println("Error retrieving hereNow data: " + exception.getMessage());
exception.getPubnubError();
show all 19 lines

Return Occupancy Only

Requires Presence

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

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

pubnub.hereNow()
.channels(Arrays.asList("my_channel")) // who is present on those channels?
.includeState(false) // include state with request (false by default)
.includeUUIDs(false) // if false, only shows occupancy count
.async(result -> { /* check result */ });
Example Response
.async(result -> {
result.onSuccess(res -> {
// Iterate through channels if the request was successful
for (PNHereNowChannelData channelData : res.getChannels().values()) {
System.out.println("Channel: " + channelData.getChannelName()); // my_channel
System.out.println("Occupancy: " + channelData.getOccupancy()); // 3
}
}).onFailure((PubNubException exception) -> {
// Handle errors if the request fails
System.err.println("Error retrieving hereNow data: " + exception.getMessage());
exception.getPubnubError();
exception.getCause();
exception.getStatusCode();
});
});

Here Now for Channel Groups

pubnub.hereNow()
.channelGroups(Arrays.asList("cg1", "cg2", "cg3")) // who is present on channel groups?
.includeState(true) // include state with request (false by default)
.includeUUIDs(true) // if false, only shows occupancy count
.async(result -> { /* check result */ });
Example Response
.async(result -> {
result.onSuccess(res -> {
// Get total occupancy across all channels if the request was successful
System.out.println("Total Occupancy: " + res.getTotalOccupancy()); // 12

// Iterate through channels in the channel group
for (PNHereNowChannelData channelData : res.getChannels().values()) {
System.out.println("Channel: " + channelData.getChannelName());
System.out.println("Occupancy: " + channelData.getOccupancy());
System.out.println("Occupants:");
for (PNHereNowOccupantData occupant : channelData.getOccupants()) {
System.out.println("UUID: " + occupant.getUuid() + " State: " + occupant.getState());
}
}
}).onFailure((PubNubException exception) -> {
show all 22 lines

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 whereNow() 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 whereNow() you can use the following method(s) in the Java SDK:

pubnub.whereNow()
.uuid(String)
* required
ParameterDescription
uuid
Type: String
Uuid of the user we want to spy on.
async *
Type: Command
Execute as async.

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

pubnub.whereNow()
.async(result -> { /* check result */ });

Returns

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

MethodDescription
getChannels()
Type: List<String>
The list of channels where the UUID is present.

Other Examples

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

pubnub.whereNow()
.uuid("some-other-uuid") // uuid of the user we want to spy on.
.async(result -> { /* check result */ });

User State

Requires Presence

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

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.

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)

Set State

this.pubnub.setPresenceState()
.channels(Array)
.channelGroups(Array)
.state(HashMap)
.uuid(String)
* required
ParameterDescription
channels
Type: Array
Channels to set state.
channelGroups
Type: Array
ChannelGroups to set state.
state
Type: HashMap
State to set.
uuid
Type: String
Set state for specific UUID.
async *
Type: Consumer<Result>
Consumer of a Result of type PNSetStateResult.

Get State

this.pubnub.getPresenceState()
.channels(Arrays)
.channelGroups(Arrays)
.uuid(String)
* required
ParameterDescription
channels
Type: Arrays
Channel name to fetch the state.
channelGroups
Type: Arrays
ChannelGroups name to fetch the state.
uuid
Type: String
UUID
async *
Type: Consumer<Result>
Consumer of a Result of type PNGetStateResult.

Basic Usage

Set State

JsonObject state = new JsonObject();
state.addProperty("is_typing", isTyping);

pubnub.setPresenceState()
.channels(Arrays.asList(channel))
.state(state)
.async(result -> { /* check result */ });

Get State

pubnub.getPresenceState()
.channels(Arrays.asList("ch1", "ch2", "ch3")) // channels to fetch state for
.channelGroups(Arrays.asList("cg1", "cg2", "cg3")) // channel groups to fetch state for
.uuid("suchUUID") // uuid of user to fetch, or for own uuid
.async(result -> { /* check result */ });

Returns

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

MethodDescription
getState()
Type: Map<String, Object>
Map of UUIDs and the user states.

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

MethodDescription
getStateByUUID()
Type: Map<String, Object>
Map of UUIDs and the user states.

Other Examples

Set state for channels in channel group

JsonObject state = new JsonObject();
state.addProperty("is_typing", isTyping);

pubnub.setPresenceState()
.channelGroups(Arrays.asList("cg1", "cg2", "cg3")) // apply on those channel groups
.channels(Arrays.asList("ch1", "ch2", "ch3")) // apply on those channels
.state(state) // the new state
.async(result -> { /* check result */ });

The above code would return the following response to the client:

if (presence.getEvent().equals("state-change")) {
boolean is_typing = presence.getState()
.getAsJsonObject()
.get("is_typing")
.getAsBoolean();
}
Last updated on