Services can measure their own response time to help with this. They can also check their own operational state to see if requests will be answered in a timely fashion. For instance, monitoring the degree of contention for a connection pool allows a service to estimate wait times. Likewise, a service can check response times on its own dependencies. If those dependencies are too slow and are required, then the health check should show that this service is unavailable. This provides back pressure through service tiers.
