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aliostad / CacheCow

An implementation of HTTP Caching in .NET Core and 4.5.2+ for both the client and the server
MIT License
849 stars 171 forks source link

Question: CacheCow: Server, How to know if data has really changed #153

Closed piemanvik closed 8 years ago

piemanvik commented 8 years ago

Hello,

Scenario:

  1. CacheCow Server set up with an sql store for strong ETags.
  2. Go to the resource database and manually edit a field in the database that is part of a resource that was previously cached (added to the sql store).

Currently as I see it CacheCow will not know that the resource has changed and will always spit out 304. I understand that this is how it is supposed to work .. and it is awesome however how do I deal with the scenario when other 3`rd party apps change data in my database that do not go through my api endpoint that uses CacheCow logic ?

Thank you.

aliostad commented 8 years ago

Hi,

The server scenario of CacheCow works on pure REST APIs where the resource changes only through the API. Three years on after building the library, I feel pure REST APIs are much rarer than I thought.

The option you have is use the IEntityTagStore interface methods to invalidate resources that change in the background - such as Remove or RemoveAllByRoutePattern. This is not ideal but I guess is the only option available.

Hope this helps

piemanvik commented 8 years ago

Hello, yeah people like to build on older technologies .. hit that resource database from willy nilly code, it is sad really.

So basically I need to first deduct server side if a resource has changed by implementing some service that does this before CacheCow gets to do things. And if it has changed then I use IEntityTagStore to do proper invalidation and then move on with normal pipeline. If not then I just continue.

Alas this would make the server always execute some code for the deduction... but at least the payload will be smaller on client side.

Thank you.

aliostad commented 8 years ago

Sure! And thanks for using CacheCow. :+1: