Hi Bertrand, I'm mostly referring to server-side queries. Here are my thoughts: 1. In case we provide hooks for SlingDataFetchers we will end up with fine-grained cache hints (for eg https://github.com/graphql-java/graphql-java/blob/c40fc1d50e91f5584cd8995b46c464d3692f20b3/src/main/java/graphql/cachecontrol/CacheControl.java could be used). After getting these hints into the ExecutionResult we would need a mechanism that combines them into an overall cache policy for the response. But the major limitation is that this can be used only in case of GET requests. Now the downside in this is that many CDNs and caching proxies only cache GET requests (not POST requests) and may have a limit on the size of a GET URL. So if we hit the limit it won't work and unfortunately GraphQL queries can be very long. Also I think that building such a mechanism is complicated.
2. Now if we think of using POST requests that are not cached by CDN the only option is application level caching. And the extension point that can be added to sling graphql is a KeyValueCache interface that will work as a service and will be implemented by the client so that the client has control on the cache implementation as you said. If the key is an Object it's even better because it helps setting the scope of the cache to PRIVATE or PUBLIC. One client can use a combination of UserId + locale + query or sessionId + query or sessionId + excutionInput for the key. And for using the cache we could update https://github.com/apache/sling-org-apache-sling-graphql-core/blob/master/src/main/java/org/apache/sling/graphql/core/engine/GraphQLResourceQuery.java#L101 to check the cache first and if not execute the query. But anyway in case of POST requests I don't see the need for caching hints. Andreea [0] https://www.apollographql.com/docs/apollo-server/performance/caching/ On 06/08/2020, 18:04, "Bertrand Delacretaz" <bdelacre...@apache.org> wrote: [Hi Andreea, On Thu, Aug 6, 2020 at 12:02 PM Andreea Miruna Moise <san...@adobe.com.invalid> wrote: > What would be the recommended way of approaching caching in case of GraphQL?... I haven't given much thought to that so far, and reading [1] [2] and [3] it looks like the best way to cache GraphQL query responses is to run those queries server-side, driven by GET requests and use traditional HTTP caching. The GraphQL core module does support server-side queries, without caching HTTP headers so far but that could be added. But I suppose you are more looking at client-driven GraphQL queries. [3] mentions an interesting (if a bit hacky) way of moving queries to the server-side to make them easier to cache. I suppose that only works if you control the client and that's probably not a standard. > ...would it make sense to have an application caching layer at Sling level that would support private > caching of the ExecutionResult?.. What we might do is provide hooks in the GraphQL Core for SlingDataFetchers to supply caching hints, along with an extension point where that caching can happen - would that work for your use cases? If the answer is yes, suggestions on how those hooks can look are very welcome! Although we do have caching services in Sling [4] I'm not sure if they are in active use at the moment, their code doesn't seem to have been touched in a long time. But if we provide somewhat abstract hooks, people can use whatever caching mechanism they want. -Bertrand [1] https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.apollographql.com%2Fblog%2Fgraphql-caching-the-elephant-in-the-room-11a3df0c23ad%2F&data=02%7C01%7Csandru%40adobe.com%7C10564da5b3a94cb5c2ac08d83a19ffa3%7Cfa7b1b5a7b34438794aed2c178decee1%7C0%7C0%7C637323230626053305&sdata=Eh%2Ba8ZBlOrJEv%2BGe4MfmT0JmE3AauMEjfGAe8fV4HhM%3D&reserved=0 [2] https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.apollographql.com%2Fdocs%2Fapollo-server%2Fperformance%2Fcaching%2F%23adding-cache-hints-statically-in-your-schema&data=02%7C01%7Csandru%40adobe.com%7C10564da5b3a94cb5c2ac08d83a19ffa3%7Cfa7b1b5a7b34438794aed2c178decee1%7C0%7C0%7C637323230626053305&sdata=LKF9VSqnyXk3jcNqmvQYVd2u6rMWfgwvnrnxq3ZOXWw%3D&reserved=0 [3] https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fapollographql%2Fapollo-link-persisted-queries&data=02%7C01%7Csandru%40adobe.com%7C10564da5b3a94cb5c2ac08d83a19ffa3%7Cfa7b1b5a7b34438794aed2c178decee1%7C0%7C0%7C637323230626053305&sdata=BDqMOoCm3MeaontiJVsCf9oSZRhQu7m17seFeaYc%2Fcw%3D&reserved=0 [4] https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fsling.apache.org%2Fdocumentation%2Fbundles%2Fcaching-services.html&data=02%7C01%7Csandru%40adobe.com%7C10564da5b3a94cb5c2ac08d83a19ffa3%7Cfa7b1b5a7b34438794aed2c178decee1%7C0%7C0%7C637323230626053305&sdata=hq9GDy%2FYWFbidPxB%2FhD1UIBsGJ1Ya1AY969jc1KkFQ4%3D&reserved=0
