Collaboration Engine

Collaboration between users is managed by collecting data into "topic" instances that are shared between all users interacting with the same part of the application. A topic can be compared to a chat room; it has an identifier (topic ID) that is unique in the context of the application, and participating members will receive all updates relating to any topic that they are participating in. Topic IDs are free-form strings that the developer may choose, such as "app" or "contract-126-address". When building a topic for a work item, it is a good convention to have the name of the entity and the identifier for the entity in the topic ID. For example, if you are making a form for editing a Person entity, and the Person has the ID 120, a good topic name would be "person/120".

Collaboration Engine includes several high-level APIs that address the specific use cases of collaboratively editing a form and having real-time discussions.

CollaborationBinder enhances the regular Vaadin Binder to share the current value of each field with all other users configured to use the same topic.

CollaborationAvatarGroup is a component that shows the avatar of every user who is present in a given topic, for example all the users currently looking at or editing the same form.

CollaborationMessageList is a component that displays messages submitted with a CollaborationMessageInput component in real time.

Collaboration Managers provide a mid-level API to handle collaborative data for the most common use cases and let developers build their own collaborative logic and custom components:

PresenceManager lets you mark user presence in a Topic and subscribe to presence changes (more in this article).

MessageManager can submit messages to a Topic and subscribe to incoming new ones (more in this article).

The low-level Topic API allows synchronizing arbitrary data between users. It is used internally by Collaboration Managers but can also be used separately to create custom collaborative user experiences. The entry point to using the Topic API is by opening a TopicConnection through CollaborationEngine::openTopicConnection.

A topic has multiple named maps and lists which are shared across connections. Each map contains many <String-key, value> pairs, while a list contains ordered values.

It is strongly recommended that shared values should be immutable instances, as subscribers are notified only when the shared value is replaced with another instance, but not when the content of an existing value is updated.

For complex values in a map, a conditional replace operation is available to prevent overwriting concurrent modifications to other parts of the shared data.