PostGraphile Realtime
Every application is different, and no more so than when it comes to their realtime requirements. Some applications are read-heavy, others write-heavy, and others are collaborative and need to put in effort to avoid conflicts between multiple people editing the same things at the same time (e.g. Google Docs).
PostGraphile focusses on customisability and extensibility; rather than giving a one-size-fits-all solution, we provide the baseline subscription functionality in core, and the rest is achieved by adding and combining plugins - the official ones, ones made by the community, or ones you've developed in-house. This enables you to use whatever technology best suits your requirements to provide the realtime features to PostGraphile.
Subscriptions
"Subscriptions" are a way of having a new message proactively sent to the client automatically whenever a particular event occurs on the server side, such as:
subscription {
chatMessageAdded(channel: 27) {
id
message
author { id name avatarUrl }
timestamp
}
}
This example subscription would result in a new response whenever a new message
is added to channel 27. Note that a normal subscription such as this one only
triggers when the event occurs (i.e. chat message added) - it does not trigger
when the message is edited, or if the author changes their avatar.
Subscriptions are part of the latest GraphQL specification, and are well supported by many clients.
Use subscriptions when:
- You need to update your UI based on events happening in the system
- You know which events should trigger an update
- Performance and scalability is important to you