This page provides a guide that demonstrates how to integrate Sendbird SyncManager onto a client app. Sendbird SyncManager can be installed through npm. Start building the add-on to your Chat SDK by clicking the Download SyncManager button below.
Note: Sendbird Chat SDK is required in order to use Sendbird SyncManager because it is an add-on feature.
How it works
SyncManager has an event-driven architecture that updates the chatting view based on data events. Both events received through the WebSocket connection and processed data in the cache are delivered to the client app by the SyncManager’s collection handlers and can be leveraged when implementing your view.
As a key component that can be used for view implementation, the
Collection holds items that comprise channel or message data. In your view, a collection instance can be binded to an event handler to subscribe to events. In the callbacks of the event handler, you can implement what jobs to execute when a specific type of event happens. The following shows a simple example of how you can create a channel collection and bind it to a collection event handler:
Background sync is a feature of SyncManager that automatically stores data fetched from Sendbird server in the local cache. When a collection is created, the background sync process starts running with the given conditions. Background sync should follow the lifecycle of a connection: the
pauseSync() method is called when a connection is lost and the
resumeSync() method is called when a connection is established.
For example, even if only 2 out of 12 channels are cached, background sync feeds the uncached Sendbird server data to the chatting view so that all 12 channels are displayed. In order for this to happen, the channel collection’s
fetch() should be called, and the collection brings the insert event for the two channels from the cache. Then, the uncached 10 channels are synchronized through background sync. After synchronization is completed, another insert event is given for the uncached 10 channels. Through this process, all 12 channels are displayed in the view.
Real-time event sync
Real-time event sync is a feature of SyncManager that listens for real-time events received through the WebSocket connection. When an event arrives, SyncManager identifies it, stores it in the cache, and delivers it to the collection handler with the appropriate action such as insert or remove.
SyncManager ensures your client app is operational during offline mode. If background sync isn’t running because a connection with the server hasn’t been established, the view can display cached data provided by SyncManager. Once a connection is re-established, the
resumeSync() resumes background sync for data synchronization.
Initialize and set up the database for SyncManager as below:
Specifies the ID of the user.
Specifies the options for how SyncManager works.
Returns Promise if not given. Otherwise returns nothing.
SendBirdSyncManager.Options has the following properties:
List of properties
Determines the maximum capacity of messages in a collection related to a chat view. Messages that exceed the maximum capacity are removed. Acceptable values are from 200 to 2,147,483,647. (Default: 2,147,483,647)
Determines the policy for handling failed messages. If delivery of a message fails, SyncManager performs different actions based on the configured policy. Acceptable values are:
Determines the maximum number of attempts to resend a failed message. Resend attempts are stopped for messages that have been resent the maximum number of attempts and they remain as failed. The
Determines the maximum number of failed messages allowed in a channel. SyncManager deletes the earliest failed message and delivers the remove event through the
Determines the number of days to retain failed messages. Once failed messages have been retained for the retention period, they are automatically removed. (Default: 7)
When the Chat SDK is connected to Sendbird server, SyncManager fetches the current user’s chat-related data from the server to update the local cache. This enables SyncManager to synchronize the local cache with the channel and message data.
Additional jobs, which detect changes in connection status and notify SyncManager, are needed when data is fetched from the server through the Chat SDK’s connection event handler: calling the
pauseSync() methods. The
resumeSync() should be called in the
onReconnectSucceeded() to run background processes for data synchronization when connected, whereas the
pauseSync() should be called in the
onReconnectStarted() to pause the background processes when disconnected.
SendBird.removeAllChannelHandlers()method shouldn’t be called because it not only removes the handlers you’ve added, but also the handlers internally managed by SyncManager.
Clear local cache
The cache can be cleared regardless of connection to Sendbird server using the
clearCache()is designed for debugging purposes only. Using it for other purposes isn’t recommended.