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Sync

Tools to synchronize data between servers.

Middlewares​

Services​

Install​

$ yarn add @semapps/sync

Use cases​

1. I want to synchronize all public data from another server​

The other server will need to install the WatcherMiddleware, which itself require the RelayService.

Your server should use the MirrorService and indicate the URL of the other server in the servers settings. This service requires the RelayService as well.

At first launch, all the public data of the other server will be downloaded (via the LDP protocol) and inserted into a separate graph named http://semapps.org/mirror.

Then the relay actor of your server will follow the relay actor of the remote server you are mirroring.

Everytime some data changes occur on the remote server, your server will receive ActivityPub activities and will update its local mirror of the data accordingly.

The http://semapps.org/mirror graph is not directly editable through LDP, but can be fetched with the ldp.resource.get action or via the SPARQL endpoint.

2. I want to aggregate the public data of Pods​

The Pod provider will need to install the WatcherMiddleware.

Your server should use the AggregatorService. This service requires the RelayService.

If Pods want their public data to be aggregated in your server, they should send an Offer > Follow activity to its relay actor.

The relay actor will automatically accept these requests, and will thus send a Follow activity to the Pod.

Whenever a public data is created, updated or deleted, the relay actor will be informed and its local cache will be updated.

Remote resources will be attached to a local container which accepts the same type of resources.

At the moment, there is no mechanism to download the existant public data when a Offer > Follow activity is received.

3. I want to synchronize data which have been shared specifically with some users​

The Pod provider will need to install the WatcherMiddleware.

When a user is being given acl:Read rights on a resource, an activity of type Announce > Create is automatically sent to them.

When this shared resource is updated or deleted, an activity of type Announce > Update or Announce > Delete is sent to all users who have acl:Read rights.

The recipients will synchronize the data received thanks to the SynchronizerService.