Presence

Get the current presence member set for this channel. In the REST client library this method directly queries Ably’s REST presence API

get(Object options, callback(ErrorInfo err, PaginatedResult<PresenceMessage> resultPage))

Gets an array of members present on the channel as PresenceMessage objects.

options parameters

clientId

when provided, will filter array of members returned that match the provided clientId string

connectionId

when provided, will filter array of members returned that match the provided connectionId“:/api/realtime-sdk/connection#id string

history(Object options, callback(ErrorInfo err, PaginatedResult<PresenceMessage> resultPage))

Gets a paginated set of historical presence message events for this channel. If the channel is configured to persist messages to disk, then the presence message event history will typically be available for 24 – 72 hours. If not, presence message events are only retained in memory by the Ably service for two minutes.

Parameters

options

an optional object containing query parameters, as specified in the presence history API documentation.

A PresenceMessage represents an individual presence update that is sent to or received from Ably.

Properties

data

The presence update payload, if provided

extras

Metadata and/or ancillary payloads, if provided. The only currently valid payloads for extras are the push, ref and privileged objects.Type:

id

Unique ID assigned by Ably to this presence updateType: String

clientId

The client ID of the publisher of this presence updateType: String

connectionId

The connection ID of the publisher of this presence updateType: String

timestamp

Timestamp when the presence update was received by Ably, as milliseconds since the epoch.Type: Integer

encoding

This will typically be empty as all presence updates received from Ably are automatically decoded client-side using this value. However, if the message encoding cannot be processed, this attribute will contain the remaining transformations not applied to the data payloadType: String

PresenceMessage.fromEncoded(Object encodedPresMsg, ChannelOptions channelOptions?) → PresenceMessage

A static factory method to create a PresenceMessage from a deserialized PresenceMessage-like object encoded using Ably’s wire protocol.

Parameters

encodedPresMsg

a PresenceMessage-like deserialized object.Type: Object

channelOptions

an optional ChannelOptions. If you have an encrypted channel, use this to allow the library can decrypt the data.Type: Object

Returns

A PresenceMessage object

PresenceMessage.fromEncodedArray(Object[] encodedPresMsgs, ChannelOptions channelOptions?) → PresenceMessage[]

A static factory method to create an array of PresenceMessages from an array of deserialized PresenceMessage-like object encoded using Ably’s wire protocol.

Parameters

encodedPresMsgs

an array of PresenceMessage-like deserialized objects.Type: Array

channelOptions

an optional ChannelOptions. If you have an encrypted channel, use this to allow the library can decrypt the data.Type: Object

Returns

An Array of PresenceMessage objects

A PaginatedResult is a type that represents a page of results for all message and presence history, stats and REST presence requests. The response from a Ably REST API paginated query is accompanied by metadata that indicates the relative queries available to the PaginatedResult object.

Properties

items

contains the current page of results (for example an Array of Message or PresenceMessage objects for a channel history request)Type: Array <Message, Presence, Stats>

Methods

first(callback(ErrorInfo err, PaginatedResult resultPage))

Returns a new PaginatedResult for the first page of results.

Boolean hasNext()

Returns true if there are more pages available by calling next and returns false if this page is the last page available.

Boolean isLast()

Returns true if this page is the last page and returns false if there are more pages available by calling next available.

next(callback(ErrorInfo err, PaginatedResult resultPage))

Returns a new PaginatedResult loaded with the next page of results. If there are no further pages, then null is returned.

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channel.history(function(err, paginatedResult) {
  console.log('Page 0 item 0:' + paginatedResult.items[0].data);
  paginatedResult.next(function(err, nextPage) {
    console.log('Page 1 item 1: ' + nextPage.items[1].data);
    console.log('Last page?: ' + nextPage.isLast());
  });
});

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