Replace Firebase with Looback strong pubsub

[kengu]

We are using Firebase to implement native push-notification in Android and iOS. This impose several problems

• Requires a google account to configure and managing the Firebase database (adds complexity)
• Notification contains sensitive information which are sent to google database (infosec)
• Adds many dependencies to the project, which must be maintained (adds overhead)
• Loopback supports pubsub , why not use it? (missed opportunuity to simplify codebase)

Proposal

• [ ] Remove implementation based on Firebase from servers and apps
• [ ] Replace it with Loopback pubsub using primus.io as transport
• [ ] Add Primus to API server, or make a bridge (proxy) to external Primus instance (more overhead)

Consequences

• [ ] Implement background app in Android and iOS which connects to Loopback pubsub
• [ ] Use Ionic native support for local notifications to show messages from Loopback pubsub

Notes

• We could opt for MQTT to implement push notification, see Pushy for an example.
• Loopback push notification support (experimental) uses Firebase to notify mobile devices.
• On iOS devices, APNS must be used since no other push notification service is allowed on iOS (source)
• Rolling our own solution entails making our own cordova plugins for Android and iOS

References

• Loopback: Publish-subscribe messaging
• Loopback: Primus as transport
• Loopback: Publish-subscribe example
• Primus: Universal wrapper for real-time frameworks
• Ionic loal notifications
• Using MQTT with Cordova
• Cordova Plugin MQTT
• Apple Push notifications tutorial