Introduction

Starting with v7.8.3 the Open-Xchange Middleware implemented a generic Push Notification Service that supports delivering arbitrary user-associated push notification messages to multiple clients in a transport-agnostic way.

Big picture

How it works

Several event-trapping locations inside the Open-Xchange Middleware are allowed to pass messages consisting of a topic name and arbitrary associated properties to the OSGi singleton service com.openexchange.pns.PushNotificationService. For instance, the listeners for new incoming mails pass a message with topic "ox:mail:new" along-side with (at least) associated mail folder.

Then that service looks-up every existing explicit or implicit subscriptions for every client that signals interest for notification's topic. A subscription provides for a certain user/client pair:

• The topics of interest; one/multiple identifiers or using a wild-card notation; e.g. "ox:mail:*"
• The transport to use
• The token to use (if any)

The payload is created according to client-associated message generator and finally sent out using the subscriptions' channels (be it APNS or FCM) to the client end-points.

Hence, in order to let a certain client for a user receive notifications for a topic, an explicit or implicit subscription needs to exist that advertises interest for notification's topic. That subscription specifies the identifier of the transport as well as the to use. In addition, a dedicated implementation of com.openexchange.pns.PushMessageGenerator needs to be OSGi-wise registered, which is responsible for yielding the appropriate message that is transported using specified transport channel to that certain client.

Explicit subscription

An explicit subscription is created by invoking com.openexchange.pns.PushSubscriptionRegistry.registerSubscription(). The subscription is permanently stored to database and associated tables are queried on incoming notifications. This is the suitable way (using the /ajax/pns?action=subscribe HTTP request) for mobile clients that are supposed to receive push notifications from a cloud push service.

Implicit subscription

An implicit subscription can be advertised through implementing and OSGi-wise registering an instance of com.openexchange.pns.PushSubscriptionProvider.