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Session Metadata

Session Metadata is an alpha feature that allows you to set and get metadata on a given session.

A session is defined as the period from when the first peer joins an empty room till the last peer leaves.

The same room can have multiple sessions. During one session the metadata will be preserved. Once a session ends the session metadata will also be cleared, that is, when the last peer leaves.


Since session metadata is an alpha feature, it does not have the following:

  1. Locks to ensure consistency of the data. If two peers update it at the same time, it will be a race condition for which one succeeds last, overwriting whatever was before.
  2. SDKs are not made aware of session metadata updates on their own. This has to be done manually. One suggested way is listed below.

Set Session Metadata

Any peer can set the session metadata by calling setSessionMetadata and pass String value to its metadata parameter.

hmsSDK.setSessionMetadata(metadata: "ENTER METADATA HERE", hmsActionResultListener: hmsActionResultListener);

You will receive an update on onSuccess Callback after successfully setting metadata in HMSActionResultListenerMethod.setSessionMetadata.

Get Session Metadata

Any peer can get metadata by calling getSessionMetadata.

String? metadata = await hmsSDK.getSessionMetadata();

Updating session metadata manually

Since no updates are sent for session metadata as it is an alpha feature, here is one suggested way of getting peers to receive it once set.

One way to notify other apps of a change in session metadata is to send a custom broadcast message when a set succeeds. The type can be set to something like "metadata" or whatever you choose and this should then be handled in the onMessage of all apps. To getSessionMetadata at that time instead of showing a message for that type.

onSuccess callback send an broadcast message as follows:

void onSuccess( {HMSActionResultListenerMethod methodType = HMSActionResultListenerMethod.unknown, Map<String, dynamic>? arguments}) { switch (methodType){ case HMSActionResultListenerMethod.setSessionMetadata: hmssdk.sendBroadcastMessage(message:"refresh", type: "metadata", hmsActionResultListener:hmsActionResultListener); break; } }

onMessage callback check for message type and update session Metadata value.

void onMessage({required HMSMessage message}) { if(message.type=="metadata") { getSessionMetadata(); return; } }