How to read or detect new data in REST Webservice

Question

I've created a REST-webservice with cakePHP for my mobile app. And the idea is to allow customers to load new data in to the system. Now the mobile app will have to check if there is new data available in the system. It can do this by asking the webservice which returns json. Now my question is how can i store the customers data so when i query the webservice it shows which data is new so i can use the new data and leave the old ones?

Answer 1

When querying you will need a way to track which data is already loaded. Depending on the type of data, sending or tracking the last update may suffice (to filter by a creation date), as may a "sent" flag per client on the server side.