Open channel
An open channel is a Twitch-style public chat where users can easily join without permission. Sendbird Chat SDK now supports two operation systems for open channels, which are classic and dynamic partitioning. These two systems offer the same features and functions, except that dynamic partitioning allows open channels to accommodate a massive number of users.
Open channels can be used in short-lived live events, such as streaming, news-feed type messaging to massive audience, or events that don't require a permanent membership.
Note: To learn about differences between open channels and group channels, see Channel types.
Classic vs. Dynamic partitioning
Classic open channels are the original open channels Sendbird has been providing, and a single classic open channel can handle up to 1,000 participants.
Note: Sendbird applications created before December 15, 2020, are using classic open channels. The classic open channels will be deprecated soon, but the classic channels created up until the deprecation date will remain and function the same way. When the deprecation takes place, all Chat SDK users will be automatically migrated to the new dynamic partitioning system. If you wish to convert to dynamic partitioning open channels beforehand, contact our support team.
On the other hand, dynamic partitioning open channels are designed to accommodate much greater number of users than the classic open channels. The dynamic partitioning open channels can have subchannels where you can divide users evenly.
Learn more about how dynamic partitioning open channel operates in the Open channel guide of Platform API.
Create a channel
An open channel is ideal for use cases that require a small and static number of channels. To create an open channel from the Sendbird Dashboard, do the following:
- In your dashboard, go to the Chat > Open channels, and then click Create channel at the top-right corner.
- In the dialog box that appears, specify the name, unique URL, cover image, and custom type of a channel.
You can also create a channel on demand or dynamically through the Chat SDK or the Chat API.
Otherwise, you can create an open channel by passing a configured OpenChannelParams
object as an argument to the parameter in the createChannel()
method like the following.
When creating a channel, you can also append additional information like cover image and description by passing several arguments to the corresponding parameters.
List of arguments
Argument | Type | Description |
---|---|---|
| string | Specifies the channel topic, or the name of the channel. |
| object | Specifies the cover image URL of the channel, or uploads a file for the cover image. |
| string | Specifies additional channel information such as a long description of the channel or |
| list | Specifies a list of one or more users to register as operators of the channel. Operators can delete any messages, and also view all messages in the channel without any filtering or throttling. |
| string | Specifies the custom channel type which is used for channel grouping. |
| interface | Specifies the |
Using the getCoverUrl()
and updateChannel()
methods, you can get and update the cover image URL of a channel.
Note: You can also create a open channel using the Chat API which helps you control channel creations. By default, the Allow creating open channels option is turned on which means that open channels can be created by any user with Sendbird Chat SDK. This may grant access to unwanted data or operations, leading to potential security concerns. To manage your access control settings, you can turn on or off each option in Settings > Application > Security > Access control list on Sendbird Dashboard.
Enter a channel
A user must enter an open channel to receive messages. The user can enter up to 10 open channels at once, which are valid only within a current connection. So when a user is disconnected from Sendbird server with the disconnect()
and reconnected to the server with the connect()
, you should make sure the user re-enters the open channels for them to continue receiving messages.
When a user who is already a participant in an open channel moves the app to the background, the user will be disconnected from Sendbird server. But when the user's app returns to the foreground, the Chat SDK will automatically re-enter the user to the participating channel.
Note: When a user is reconnected by attempts of the
SendBird
instance from a temporary unstable connection, the Chat SDK will automatically re-enter the user to the participating channel.
Exit a channel
If a user exits an open channel, the user can't receive any messages from that channel.
Freeze and unfreeze a channel
An open channel can be freezed only with the Sendbird Dashboard or Chat API as opposed to a group channel which operators of the channel can do that via the Chat SDK.
To freeze, go to your dashboard and do the following: on the Chat > Open channels, select an open channel to freeze, and click the Freeze icon at the upper right corner. To unfreeze, click the icon again with the frozen channel selected.
Note: In a frozen channel, participants can't chat with each other but the operators can send a message to the channel.
Delete a channel
Only the operators of an open channel can delete the channel. Otherwise, an error is returned through the OpenChannelDeleteHandler
.
Note: The following code works properly in the operators' client apps only.
Retrieve a list of channels
You can retrieve a list of OpenChannel
objects using the next()
method of an OpenChannelListQuery
instance like the following.
Retrieve a channel by URL
Since a channel URL is a unique identifier of an open channel, you can use a URL when retrieving a channel object.
Note: We recommend that you store a user's channel URLs to handle the lifecycle or state changes of your app, or any other unexpected situations. For example, when a user is disconnected from Sendbird server due to switching to another app temporarily, you can provide a smooth restoration of the user's state using a stored URL to fetch the appropriate channel instance.
Send a message
In an entered channel, a user can send messages of the following types:
Message type | Class | Description |
---|---|---|
Text | A text message sent by a user | |
File | A binary file message sent by a user |
In addition to these message types, you can further subclassify a message by specifying its custom type. This custom type takes on the form of a String
and can be used to search or filter messages. It allows you to append information to your message and customize message categorization.
The following code shows several types of parameters that you can configure to customize text messages by using UserMessageParams
. Under the UserMessageParams
object, you can assign specific values to message
, data
and other properties. By assigning arbitrary string to the data
property, you can set custom font size, font type or JSON
object. To send your messages, you need to pass the UserMessageParams
object as an argument to the parameter in the sendUserMessage()
method.
Through the onSent()
callback method of the sendUserMessage()
method, Sendbird server always notifies whether your message has been successfully sent to the channel. When there is a delivery failure due to network issues, an exception is returned through the callback method.
A user can also send binary files through the Chat SDK. The two ways to send a binary file are: sending the file itself, or sending a URL.
Sending a raw file means you're uploading it to Sendbird server where it can be downloaded in client apps. When you upload a file directly to the server, there is a size limit imposed on the file depending on your plan. You can see the limit in your dashboard and adjust it with our sales team.
The other option is to send a file hosted on your server. You can pass the file's URL, which represents its location, as an argument to a parameter. In this case, your file is not hosted on Sendbird server and it can only be downloaded from your own server. When you send a file message with a URL, there is no limit on the file size since it's not directly uploaded to Sendbird server.
Note: You can use
sendFileMessages()
, which is another method that allows you to send up to 20 file messages per one method call. Refer to our API Reference to learn more about it.
The following code shows several types of parameters that you can configure to customize file messages by using FileMessageParams
. Under the FileMessageParams
object, you can assign specific values to customType
and other properties. To send your messages, you need to pass the FileMessageParams
object as an argument to the parameter in the sendFileMessage()
method.
Through the onSent()
callback method of the sendFileMessage()
method, Sendbird server always notifies whether your message has been successfully sent to the channel. When there is a delivery failure due to network issues, an exception is returned through the callback method.
Send a critical alert message to iOS devices
A critical alert is a notification that can be sent to iOS devices even when mute or Do Not Disturb is turned on. Critical alert messages can be sent to iOS devices through the sendUserMessage()
and sendFileMessage()
methods. To do so, create an AppleCriticalAlertOptions
instance and set it as an attribute of a UserMessageParams
instance. Then pass the created UserMessageParams
instance as an argument to a parameter in the sendUserMessage()
or sendFileMessage()
method.
Note: To learn more about how to set critical alerts, visit Apple critical alerts.
Receive messages through a channel event handler
Messages sent from other participants can be received through the onMessageReceived()
method in the channel event handler. A BaseMessage
object for each received message is one of the following three message types.
Message type | Class | Description |
---|---|---|
Text | A text message sent by a user | |
File | A binary file message sent by a user | |
Admin | A text message sent by an admin through the Chat API |
The UNIQUE_HANDLER_ID
is a unique identifier to register multiple concurrent handlers.
Reply to a message
Users can reply to a specific message in a channel through either the sendUserMessage()
or sendFileMessage()
method.
Depending on the type of the message a user intends to reply with, create a UserMessageParams
or a FileMessageParams
object and then specify the parentMessageId
property of the object. Sending reply messages works the same way as sending regular messages to a channel, except replies have an additional parentMessageId
property.
Reply with a text message
When replying to a message through the sendUserMessage()
method, specify and pass a UserMessageParams
object as an argument to a parameter in the method.
List of arguments
Argument | Type | Description |
---|---|---|
| long | Specifies the unique ID of a parent message. A parent message is a message that has a thread of replies. If the message sent through the |
Reply with a file message
When replying with a file message through the sendFileMessage()
method, specify and pass a FileMessageParams
object as an argument to a parameter in the method.
List of arguments
Argument | Type | Description |
---|---|---|
| long | Specifies the unique ID of a parent message. A parent message is a message that has a thread of replies. If the message sent through the |
Mention other participants in a message
When a participant wants to call the attention of other participants in an open channel where push notifications are not allowed by default, they can mention those participants in a message. To do so, you should:
- Specify a list of the user IDs to mention.
- Add the list to either
UserMessageParams
orFileMessageParams
which may contain options for further action. - Pass the params to either
sendUserMessage()
orsendFileMessage()
. - Then only up to 10 participants mentioned in the message will be notified.
Load previous messages
Using the load()
method of a PreviousMessageListQuery
instance which returns a list of BaseMessage
objects, you can retrieve a set number of previous messages in an open channel. With a returned list, you can display the past messages in your UI once they have loaded.
List of arguments
Argument | Type | Description |
---|---|---|
| int | Specifies the number of results to return per call. Acceptable values are 1 to 100, inclusive. The recommended value for this parameter is 30. |
| boolean | Determines whether to sort the retrieved messages in reverse order. If true, returns a list of messages which the latest comes at first and the earliest at last. the results are sorted in reverse order. If false, returns a list of messages which the earliest comes at first and the latest at last. |
A limit
parameter determines how many messages should be included in a returned list. A PreviousMessageListQuery
instance itself does pagination of a result set based on the value of the limit
parameter, and internally manages a token to retrieve the next page in the result set.
Each time the load()
method is called, the instance retrieves a set number of messages in the next page and then updates the value of the token to complete the current call and prepare a next call.
If you create a new PreviousMessageListQuery
instance and call the load()
method, a set number of the most recent messages are retrieved because its token has nothing to do with the previously created instance. So we recommend that you create a single query instance and store it as a member variable for traversing through the entire message history.
Note: Before calling the
load()
method again, you must receive a success callback through theonResult()
first.
Load messages by timestamp or message ID
You can retrieve a set number of previous and next messages on both sides of a specific timestamp in an open channel. You can do the same using a message ID as well.
By timestamp
Use the getMessagesByTimestamp()
method to retrieve a set number of previous and next messages on both sides of a specific timestamp.
The following code shows several types of parameters that you can configure to customize a message query by using MessageListParams
. Under the MessageListParams
object, you can assign values to previousResultSize
, messageType
, customType
, and other properties. To retrieve messages in a channel, you need to pass the MessageListParams
object as an argument to the parameter in the getMessagesByTimestamp()
method.
List of arguments
Argument | Type | Description |
---|---|---|
| long | Specifies the timestamp to be the reference point of a retrieval, in Unix milliseconds. |
| boolean | Determines whether to include the messages sent exactly on the |
| int | Specifies the number of messages to retrieve, which are sent previously before a specified timestamp. Note that the actual number of results may be larger than the set value when there are multiple messages with the same timestamp as the earliest message. |
| int | Specifies the number of messages to retrieve, which are sent later after a specified timestamp. Note that the actual number of results may be larger than the set value when there are multiple messages with the same timestamp as the latest message. |
| boolean | Determines whether to sort the retrieved messages in reverse order. If false, the results are in ascending order. |
| enum | Specifies the message type to filter the messages with the corresponding type. Acceptable values are MessageTypeFilter.ALL, MessageTypeFilter.USER, MessageTypeFilter.FILE, and MessageTypeFilter.ADMIN. |
| string | Specifies the custom message type to filter the messages with the corresponding custom type. |
By message ID
You can also retrieve a set number of previous and next messages on both sides of a specific message ID in an open channel, using the getMessagesByMessageId()
method and MessageListParams
object.
List of arguments
Argument | Type | Description |
---|---|---|
| long | Specifies the unique ID of the message to be the reference point of a retrieval. |
| boolean | Determines whether to include the message identified with a specified message ID. |
| int | Specifies the number of messages to retrieve, which are sent previously before a specified message ID. |
| int | Specifies the number of messages to retrieve, which are sent later after a specified timestamp. |
| boolean | Determines whether to sort the retrieved messages in reverse order. If false, the results are in ascending order. |
| enum | Specifies the message type to filter the messages with the corresponding type. Acceptable values are MessageTypeFilter.ALL, MessageTypeFilter.USER, MessageTypeFilter.FILE, and MessageTypeFilter.ADMIN. |
| string | Specifies the custom message type to filter the messages with the corresponding custom type. |
List messages along with their replies by timestamp or message ID
You can retrieve messages and their replies in a specific thread through one of the load()
, getMessagesByTimestamp()
, or getMessagesByMessageId()
methods.
First, messages in an open channel must be retrieved. The load()
method of a PreviousMessageListQuery
instance returns a list of BaseMessage
objects. By using this method, you can retrieve previous messages in a specific channel.
List of arguments
Argument | Type | Description |
---|---|---|
| int | Specifies the number of results to return per call. Acceptable values are 1 to 100, inclusive. The recommended value for this parameter is 30. |
| boolean | Determines whether to sort the retrieved messages in reverse order. If false, the results are in ascending order. |
| boolean | Determines whether to include the thread information of the messages in the results when the results contain parent messages. |
| enum | Specifies the type of message to include in the results. |
| boolean | Determines whether to include the information of the parent messages in the result. (Default: false) |
| boolean | (Deprecated) Determines whether to include replies in the results. |
| boolean | (Deprecated) Determines whether to include the parent message text in the results when the retrieved messages are replies in a thread. If the type of the parent message is |
By timestamp
The getMessagesByTimestamp()
method of a BaseChannel
instance retrieves a list of BaseMessage
objects.
When using the method above, you can also pass a MessageListParams
object as an argument to the parameter in the getMessagesByTimestamp()
method.
List of arguments
Argument | Type | Description |
---|---|---|
| long | Specifies the timestamp to be the reference point for messages to retrieve, in Unix milliseconds format. Messages sent before or after the timestamp can be retrieved. |
| int | Specifies the number of messages to retrieve that were sent before the specified timestamp or message ID. |
| int | Specifies the number of messages to retrieve that were sent after the specified timestamp or message ID. |
| boolean | Determines whether to include the messages with the matching timestamp or message ID in the results. |
| boolean | Determines whether to sort the retrieved messages in reverse order. If false, the results are in ascending order. |
| boolean | Determines whether to include the thread information of the messages in the results when the results contain parent messages. |
| enum | Specifies the type of message to include in the results. |
| boolean | Determines whether to include the information of the parent messages in the result. (Default: false) |
| boolean | (Deprecated) Determines whether to include replies in the results. |
| boolean | (Deprecated) *Determines whether to include the parent message text in the results when the retrieved messages are replies in a thread. If the type of the parent message is |
By message ID
The getMessagesByMessageId()
method of a BaseChannel
instance retrieves a set number of previous and next messages on both sides of a specific message ID in a channel.
List of arguments
Argument | Type | Description |
---|---|---|
| long | Specifies the message ID to be the reference point for messages to retrieve. Messages sent before or after the message with the matching message ID can be retrieved. |
List replies of a parent message
With the timestamp of the parent message, you can retrieve a single message with its replies by passing a TreadMessageListParams
object as an argument to the parameter in the getThreadedMessagesByTimestamp()
method.
List of arguments
Argument | Type | Description |
---|---|---|
| long | Specifies the timestamp to be the reference point of the retrieval, in Unix milliseconds format. |
| int | Specifies the number of messages to retrieve that were sent before the specified timestamp. |
| int | Specifies the number of messages to retrieve that were sent after the specified timestamp. |
| boolean | Determines whether to include the messages with the matching timestamp in the results. |
| boolean | Determines whether to sort the retrieved messages in reverse order. If false, the results are in ascending order. |
| boolean | Determines whether to include the information of the parent messages in the result. (Default: false) |
| boolean | (Deprecated) Determines whether to include the parent message text in the results when the messages are replies in a thread. If the type of the parent message is |
Retrieve a message
You can retrieve a specific message by creating and passing the MessageRetrievalParams
object to the getMessage()
method as a parameter.
List of arguments
Argument | Type | Description |
---|---|---|
| String | Specifies the URL of the channel to retrieve the message. |
| BaseChannel.ChannelType | Specifies the type of the channel. |
| long | Specifies the unique ID of the message to retrieve. |
Update a message
A user can update any of their own text and file messages sent. An error is returned if a user attempts to update another user's messages. In addition, channel operators can update any messages sent in the channel.
If a message is updated, the onMessageUpdated()
method in the channel event handler will be invoked on all channel participants' devices except the one that updated the message.
Delete a message
A user can delete any messages sent by themselves. An error is returned if a user attempts to delete the messages of other participants. Also channel operators can delete any messages in the channel.
If a message is deleted, the onMessageDeleted()
method in the channel event handler will be invoked on all channel participants' devices including the one that deleted the message.
Copy a message
A user can copy and send their own message in the same channel or to another channel.
List of arguments
Argument | Type | Description |
---|---|---|
| object | Specifies a target channel to send a copied message to. |
| object | Specifies a message to copy. |
| interface | Specifies the handler interface which contains the |
Retrieve a list of participants
You can retrieve a list of participants who are currently online and receiving all messages from an open channel.
Retrieve the latest information on participants
To retrieve the latest and updated information on each online participant in an open channel, you need another ParticipantListQuery
instance for the channel. Like the Retrieve a list of participants section above, create a query instance using the channel.createParticipantListQuery()
, and then call its next()
method consecutively to retrieve the latest.
You can also retrieve the latest and updated information on users at the application level. Like the Retrieve a list of users section, create a new ApplicationUserListQuery
instance using the SendBird.createApplicationUserListQuery()
, and then call its next()
method consecutively to retrieve the latest.
When retrieving the online (connection) status of a user, by calling the user.getConnectionStatus()
at each User
object in a returned list, you can get the user's current connection status. The getConnectionStatus()
returns one of the following two values:
getConnectionStatus()
Value | Description |
---|---|
User.ConnectionStatus.OFFLINE | The user is not connected to Sendbird server. |
User.ConnectionStatus.ONLINE | The user is connected to Sendbird server. |
Note: If you need to keep track of the connection status of some users in real time, we recommend that you call periodically the
next()
method of anApplicationUserListQuery
instance with itsuserIdsFilter
filter specified, perhaps in intervals of one minute or more.
Retrieve a list of operators
You can follow the simple implementation below to retrieve a list of operators who monitor and control the activities in an open channel.
Register operators
You can register participants as operators of an open channel.
Cancel the registration of operators
You can cancel the registration of operators from an open channel but leave them as participants.
If you want to cancel the registration of all operators in a channel at once, use the following code.
Retrieve a list of banned or muted users
You can create a query to get a list of banned or muted users in an open channel. This query is only available for users who are registered as operators of an open channel.
Ban and unban a user
Operators of an open channel can remove any users that behave inappropriately in the channel by using our Ban feature. Banned users are immediately expelled from a channel and allowed to participate in the channel again after the time period set by the operators. Operators can ban and unban users from open channels using the following code.
Note: You can also use
banUserWithUserId()
andunbanUserWithUserID()
methods, instead ofbanUser()
andunbanUser()
methods, as they have the same functionalities.
Mute and unmute a user
Operators of an open channel can prohibit the selected users from sending messages using our Mute feature. Muted users remain in the channel and are allowed to view the messages, but can't send any messages until the operators unmute them. Operators can mute and unmute users in open channels using the following code:
Note: You can also use
muteUserWithUserId()
andunmuteUserWithUserID()
methods, instead ofmuteUser()
andunmuteUser()
methods, as they have the same functionalities.
Report a message, a user, or a channel
In an open channel, a user can report suspicious or harassing messages as well as the other users who use abusive language. The user can also report channels if there are any inappropriate content or activity within the channel. Based on this feature and our report API, you can build your own in-app system for managing objectionable content and subject.
List of arguments
Argument | Type | Description |
---|---|---|
| object | Specifies the message to report for its suspicious, harassing, or inappropriate content. |
| object | Specifies the user who uses offensive or abusive language such as sending explicit messages or inappropriate comments. |
| enum | Specifies a report category which indicates the reason for reporting. Acceptable values are limited to ReportCategory.SUSPICIOUS, ReportCategory.HARASSING, ReportCategory.INAPPROPRIATE, and ReportCategory.SPAM. |
| string | Specifies additional information to include in the report. |