Handling Client Interactions

The RESTrict Framework classifies three types of communication interactions between the client and the server.

Accessor operations

When accessing state of the application, the server immediately responds with the state queried by the client.

Fig. 11 Accessor operations result in synchronous responses

State modification subscriptions

The client can subscribe to state changes of resources. This creates a duplex communication channel to receive state changes through the connection, as well as unsubscribe from state change syndication.

Fig. 12 Client subscribes for resource modification notifications

Mutation operations

Clients can mutate the state of the application (of course). In doing so, the client sends the mutation request to the server. If the server has a push notification channel open to the client, then it will send the client a notification with the final state of the application in the context of the modified resource.

Fig. 13 Mutation operations result in asynchronous notifications

If the server does not have a channel to send push notifications, then the client can later ask for the result of the transaction.

Fig. 14 Client queries for state modification when server push fails