I know that a web browser check if a resource is modified/expired within a given timestamp to decide if downloading such resource or not.
So, here come two questions:
i) generally speaking how exactly this mechanism works in background, which requests/reponse are made by browser and server
ii) I have built a simple REST php web service that serves a json file by means of GET request. And GET is actually the only protocol implemented. In the response I am correctly including all the necessary header file. Is there something server side I need to implement for making my web service compliant to such 'check for last update therefore serve or not the resource' mechanism ? In particular my client is an iOS app, which by default is strictly following the http caching rule.