The error handler approach is OK. Regarding the cache, the `apply` method will be actually called every time you call the `getExtensionApiForZone` method, so the cache might help saving some requests.
The `ZoneToEndpoint` already uses a cache. The supplier it delegates to is cached (and configured [here](https://github.com/jclouds/jclouds/blob/master/core/src/main/java/org/jclouds/location/config/LocationModule.java#L174-L182)). In this case, you could declare the cache in the [GlanceHttpApiModule](https://github.com/jclouds/jclouds-labs-openstack/blob/master/openstack-glance/src/main/java/org/jclouds/openstack/glance/v1_0/config/GlanceHttpApiModule.java). Sounds good? Nice job, btw! Next is to properly update the unit tests. As you'll see, the existing "expect" unit tests define a set of `request/response` pairs. They have to be modified to include this "version negotiation" in the request flow, in the form of a mocked request/response pair. --- Reply to this email directly or view it on GitHub: https://github.com/jclouds/jclouds-labs-openstack/pull/82#issuecomment-37755874
