Listening to inbox & outbox

To listen to a Pod’s inbox and outbox, applications can use Solid Notifications, and for backend-to-backend we recommend webhook subscriptions.

The mechanism for generating webhooks and subscribing to collections can be tedious, so fortunately we provide services and mixins that make this much easier.

Watching for activities

We provide a PodActivitiesWatcherService. It will check for all users who have granted the apods:ReadInbox' and apods:ReadOutbox ’ special rights, and will automatically subscribe to webhooks.

Each service can monitor certain types of activity by calling the service’s watch action like this:

await ctx.call('pod-activities-watcher.watch', {
  matcher: {
    type: 'Invite',
    object: {
      type: 'Event'
    }
  },
  actionName: 'my-service.my-action',
  boxTypes: ['inbox', 'outbox'],
  key: 'invite-event'
});

In the above example, whenever an activity matching the Invite > Event pattern is detected in either the user’s inbox or outbox, the my-service.my-action action is called.

This action receives as parameters key (the custom key passed above), boxType (“inbox” or “outbox”), dereferencedActivity (the activity dereferenced according to the provided pattern), and actorUri (the URI of the actor who owns the inbox or outbox).

Services dedicated to handling activities

To make things even simpler, we also provide a PodActivitiesHandlerMixin that can be integrated into any service.

It works on the same principle as SemApps’ ActivitiesHandlerMixin, except that it will use the PodActivitiesWatcherService to subscribe to the user’s inbox/outbox and listen for activities.

const { PodActivitiesHandlerMixin } = require('@activitypods/app');

module.exports = {
  name: 'invite',
  mixins: [PodActivitiesHandlerMixin],
  activities: {
    invite: {
      match: {
        type: 'Invite',
        object: {
          type: 'Event'
        }
      },
      async onEmit(ctx, activity, actorUri) {
        console.log(`You sent an invitation for ${activity.object.name}!`);
      },
      async onReceive(ctx, activity, actorUri) {
        console.log(`You have been invited to ${activity.object.name}!`);
      }
    }
  }
};