Synchronizer Service

An ActivityPods service to notify of objects' updates.

When a watched object is updated or deleted, automatically send an activity to the actors who have the right to view this object.

Usage

The SynchronizerService is included in the CoreService. The easiest way to make use of it is to import the SynchronizerMixin along with the ControlledContainerMixin.

const { ControlledContainerMixin } = require('@semapps/ldp');
const { SynchronizerMixin } = require('@activitypods/synchronizer');

module.exports = {
  name: 'events',
  mixins: [SynchronizerMixin, ControlledContainerMixin], // In that order
  settings: {
    path: '/events',
    acceptedTypes: ['Event']
  }
}

Note: The SynchronizerMixin must be added before the ControlledContainerMixin, as it overrides its delete action.

Actions

watch

Watch a new type of object.

Parameters

| Property | Type | Default | Description | |----------|----------|--------------|---------------------------------------| | type | String | required | The type of resource we want to watch |

announceUpdate

Announce an object update to all actors who have the right to view this object.

Parameters

| Property | Type | Default | Description | |-------------|----------|--------------|--------------------------------------------| | objectUri | String | required | The URI of resource which has been updated | | newData | Object | required | The content of the resource (in JSON-LD) |

announceDelete

Announce an object deletion to all actors who have the right to view this object.

Parameters

| Property | Type | Default | Description | |-------------|----------|--------------|-----------------------------------------------------------------| | objectUri | String | required | The URI of resource which has been deleted | | oldData | Object | required | The content of the resource before it was deleted (in JSON-LD) |

Handled activities

Announce update

{
  "type": "Announce",
  "object": {
    "type": "Update",
    "object": {
      "type": "[WATCHED TYPES]"
    }
  }
}

Emitter's side effects

• None

Recipients' side effects

• The object cached in the recipients' PODs is refreshed

Announce delete

{
  "type": "Announce",
  "object": {
    "type": "Delete",
    "object": {
      "formerType": "[WATCHED TYPES]"
    }
  }
}

Emitter's side effects

• None

Recipients' side effects

• The object cached in the recipients' PODs is deleted