System Architecture - Interview Questions

11. Identify the two update types and explain their differences.
If an online work process updates the database directly the update will be synchronous, or immediate. If on the other hand the online work process uses an update work process the update type will be asynchronous, which has log records.

12. What has log records?
Asynchronous updating. Online programs generate log records which are then handled by an update work process after the online portion is complete.

13. What are the types of log records?
Primary U1, critical timing and must complete successfully for continuation. If an error occurs, processing ends and a rollback occurs.
Secondary U2, several may line up after a U1, if an error occurs, that block stops,
rolls back and processing continues.

14. What does a service refer to within R3?
A service is a process or group of processes that perform a specific system function ( i.e. “service” ) and often provide an application programming interface (API) for other processes to call.

15. What does it mean that R3 is a multi-client system?
Highly suited to the multi-level client/server architectures, for example, the three level concept for the presentation, application logic and data storage.