@activitypods/synchronizer

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