The backend OData source can proactively send notifications to Hybrid Apps.
SAP Mobile Platform enables this by exposing an HTTP based push interface http://supserver:port/notifications/ApplicationConnectionID.
The Hybrid App must inform the backend of its ApplicatonConnectionID, usually on startup. You can obtain this by using the hwc.getApplicationConnectionID() JavaScript API. The backend service exposes an endpoint where said ApplicationConnectionID can be sent when the Hybrid App starts up or "subscribes." When the push notification is received, it can be handled in native code or JavaScript.