Publication
Having decided on your topic structure and the format of your data, consider how you publish the data through the topics.
Pub-sub is the primary model of data distribution used by Diffusion™ Cloud. Clients subscribe to a topic. When data is
published to the topic as an update, Diffusion Cloud pushes that
update out to all of the subscribed clients.
A client can both publish to topics and subscribe to topics, depending on the
permissions that client has.
Concepts
- Update
- An update is data published to a topic by a client that is applied to the topic to change the topic state. The updated data is then pushed out to all subscribing clients.
- State
- The latest published values of all data items on the topic. The state of a topic is stored on Diffusion Cloud.
- Value
- A value is an update that contains the current state of all data on the topic.
- Delta
- A delta is an update that contains only those items of data that have changed on the topic since the last update was sent.
- Topic loading
- When a client first subscribes to a topic, it is sent a topic load message. A topic load is a value update that contains the current state of the topic.
- Fetch
- A request for the current state of all data on the topic. A client can fetch a topic's state without being subscribed to the topic. This request-response mechanism of getting data from a topic is separate from the pub-sub mechanism.
This page last modified: 2017/02/05