Hello :slightly_smiling_face: Just a quick questio...

# squarelibraries

[Yoni Obia]

Hello 🙂
Just a quick question about okhttp and cache, one of my client is asking me to add a cache strategy such as:
1. get data and cache it
2. if the data is cached <30 min then just show cache
3. if cache > 30 min && hasInternet try get data and cache but if for some reason the call fail show cache
4. delete all cache which are 1 week old
I’ve never seen anything like this done client side, do you guys have any advice to either implement this or maybe some header I don’t know about

I’ve setup a small server in localhost to test things out, I’ve added a Cache-Control: max-age=60;max-stale=120 to test things with OkHttp, the max-age prevent calling the server for 60 seconds but the max-stale isn’t doing anything or I’m not using it properly

[jessewilson]

The only thing that’s tricky about this is 3, ‘cache if error’.

To implement this on the client, make your first HTTP request with no cache-control headers, and then in a catch clause you make a second HTTP request that adds cache-control headers that specify that you’re okay reading a stale value from the cache.

[jessewilson]

On the server you’ll serve a Cache-Control header that says ‘fresh for 30 minutes’

[jessewilson]

OkHttp doesn’t have a mechanism to delete things from the cache on a schedule. But you can use cache headers to prevent responses older than 7 days from being returned

[Yoni Obia]

I’ve tried reading stale value from the cache when offline but I’m getting a java.net.ConnectException: Failed to connect to /10.0.2.2:8000 while the response should be returned because of the max-stale=120

[jessewilson]

Add only-if-cached to prevent the network call

[jessewilson]

maybe also add max-age=120 ?

[Yoni Obia]

Why add max-age=120 isn’t the 2 other enough to use the cache?