How Client SDKs Work
The client architecture has different goals and different operating characteristics from the server side SDKS. The goals of the clients are:
- Make lookups as quickly as possible
- Don't leak raw configuration data to the end user
- Give clear and configurable behavior options if a connection cannot be made
With those goals in mind, the architecture is:
Typically clients will make a single request and receive the values of all FeatureFlags for a given user.
Multiple requests only happen if you change the attributes of an identity as you're going.
Note that evaluation happens server side. This helps prevent potentially sensitive data from leaking out of your system. The client will be returned a list that is basically:
See server SDKs to compare.
Client Side Reliability
Each user that needs flags evaluated is a different request to Prefab. So what happens if Prefab goes down?
First the good news. All active users will be unaffected, because they will have cached values in the CDN. If you make a change to your feature flags, it won't be reflected, but in general logged-in users will have a consistent experience.
The less good news. Evaluation happens server side, so if we don't have a server we won't have values.
The default timeout is
10 sec, but you can set this in client initialization.