Based on common use cases, IM provides the following default group types:

Differences in basic group capabilities

Note：

• Ordinary members of a work group (Work) can modify only the group name, introduction, announcement, and group profile photo URL, but not other group profile information.
• If the roles of a group type cannot meet your business needs, you can add roles by setting member-level custom fields.
• It is necessary to obtain the information about some members in scenarios where an audio-video group displays a list of some of its members.

Differences in joining a group

Note：

• Exact search is to search for a group by group ID. Fuzzy search is to search for a group by fields such as the group name.
• Approval for joining a group: the group owner and admin can approve or reject applications made by non-members to join the group. Only approved users can join the group.
• For a group type that does not support the invitation of non-members to a group, group members can share the group ID with non-members in the app so that the non-members can join the group.

Differences in member management capabilities

Note：

Muted group members cannot send group chat messages within the mute period.

Differences in group limits

Note：

• For an SDKAppID of the Pro Edition or Flagship Edition, up to 10,000 groups (the number of created groups minus the number of deleted groups) can be added in a day regardless of the group type.
• For an SDKAppID of the Pro Edition or Flagship Edition, up to 100,000 groups can be added for free in a month. If this quota is exceeded, fees for usage exceeding the free quota will be charged. It is recommended that you delete the groups that are no longer needed in a timely manner.

Differences in message capabilities

Note：

• For a group that requires activation, before the group owner sends a message, the group is inactive and invisible to all group members except the group owner. A group that does not require activation is visible to all group members once it is created.
• Currently, offline push is available only on Android (Android offline push) and iOS (APNs push) platforms.
• The work group, public group, and meeting group have the historical message storage capability, which allows historical messages to be stored for 7 days (30 days for the Flagship Edition) free of charge by default. If you need a longer storage period, change the storage period of historical messages in the console. Increasing the storage period of historical messages is a value-added service. For more information on pricing, see Pricing.

Differences in batch import and automatic repossession

Note：

To enable group repossession, submit a ticket. After configuration, inactive groups will be cleaned up by group type. An inactive group is a group in which no messages are sent and no member changes occur.

Group Data Structure

Group profile

Note：

The permissions to modify the group name, introduction, announcement, and profile photo URL are described as follows:

• In a work group, any member can modify them.
• For other group types, only non-ordinary members can modify them.

Group member profile

Custom Group Types

If the group types provided by IM cannot meet your needs, you can submit a ticket to apply to modify existing group types or add custom group types.
For example, you can create a group that is used in an office environment. This group is similar to a work group, but every member has the highest level of management permissions and can view messages sent before they join the group. In this case, you can:

• Choose the work group type and submit a ticket to apply to enable the view historical messages before joining and allow ordinary members to remove members options.
• Submit a ticket to apply for a new group type named OAGroup. Specify work group as the reference type and enable the view historical messages before joining and allow ordinary members to remove members options.

Note：

• When creating a group type, you must specify a group type as a reference type. Note that BChatRoom in SDK of earlier versions cannot be specified as a reference type.
• After configuration, the new group type will have new features that are specified in the ticket, and the same features as the reference type.

Custom Group IDs

When a group is created in the app, IM assigns a default group ID to the new group by default. This default group ID starts with @TGS# and is unique in the app.
IM also allows you to customize group IDs that are simple and easy to remember and communicate. A custom group ID must be a string of ASCII characters (0x20-0x7e) with a length less than 48 bytes. Do not use @TGS# as the prefix to avoid confusion with assigned group IDs.

Custom Fields

IM allows you to configure up to 10 group-level custom fields and 5 member-level custom fields based on your business needs. With custom fields, apps can attach additional data to groups, and the data can be read and written through existing APIs. Custom fields cannot be deleted once created and applied.

Description

Custom fields have the following characteristics:

• Their values are expressed in key-value format.
• Key is a string with a length less than 16 bytes. Its name contains only uppercase and lowercase letters, numbers, and underscores (_).
• Value is a buffer customized by the user, which can be binary data. Group-level values have a maximum length of 512 bytes, while member-level values have a maximum length of 64 bytes.
• You can configure the least read permission and the least write permission for each key.

The read and write permissions of a custom field are listed as follows, from high to low:

1. Readable and writable by the app admin.
2. Readable and writable by the group owner.
3. Readable and writable by the group admin.
4. Readable and writable by group members.
5. Readable and writable by anyone, including non-members.

For example, an app needs to extend the GroupLevel field for groups and the value of this field is a number representing the level of a group. If this level information is calculated by the app backend, then the least write permission should be writable by the app admin. If the field is part of the public profile of the group, its least read permission should be readable by anyone, including non-members.

If the value to be stored is a number, we recommend that C and C++ developers store it as a string instead of binary data. For example, when the number to be stored is 1, store it as string 1 instead of binary data 0x01. In the future, IM will offer more operations for custom fields, such as specific mathematical operations on values, which will be performed on the basis of string-type numbers.

Configuration method

Custom fields at these two levels can be configured in the IM console.
To configure member-level custom fields, you need to specify the group type first. Audio-video group and custom group types that are configured based on it do not support custom fields at the group member level, because these types of groups do not store member profiles.
The self read and write permissions indicate whether members can read and write their own member-level custom fields. For example, a member-level customer field named MemberLevel represents the level of a member in a group. Group members can read but not modify their own levels, and therefore their self read and write permissions are set to readable/unwritable for this field.

Custom Callbacks

Third-party callback is an important means to meet the special requirements of apps. It provides users with the capability to customize actions.
IM's group system supports different callbacks. For more information, see Third-Party Callback Overview and Callback Command List.