Comp150CPA: Clouds and Power-Aware Computing
Quiz 1 -- Mar 2, 2011
Closed book and notes

Name: ____________________________ login: ______________

Please write all of your answers on this sheet. No books, notes, or electronic devices are allowed.

1. (40 points) Please fill in the blanks to create correct statements.
   
   
   The ability of a cloud to respond to unforeseen changes in load is called ________₁________. The reason that this response must be dynamic is that unneeded cloud resources consume ________₂________ and could be used by other applications.
   
   
   In AppEngine, to hide cloud latency from the customer, a synchronous server-side data access routine is paired with a(n) ________₃________ client-side interface. Server-side routines deal with ________₄________ data, which client-side routines should not do.
   
   
   Eventual consistency is useful when using the cloud to store ________₅________, while strong consistency is required when one is using the cloud to store ________₆________.
   
   
   A Service Level Objective (SLO) determines what constitutes ________₇________ behavior for a service, while a Service Level Agreement (SLA) determines ________₈________ for not meeting objectives.
2. (10 points) Explain briefly why it is difficult to directly relate load average on a server with its response time to queries.
   
   
   
   
   
   
   
3. (10 points) Explain briefly what behavior results from combining flowless switching with eventual consistency.
   
   
   
   
   
   
   
   
   
4. (10 points) Explain briefly what happens to service behavior when one triples the number of (edge) servers that provide a service.
   
   
   
   
   
   
   
   
   
5. (15 points) In assignment 2, a few groups reported that it was necessary to detach a persistent object from its persistence store, change it, and then make it persistent again in order to change its contents. Otherwise, changes were ignored. Why did they have to do this?
   
   
   
   
   
   
   
   
   
6. (15 points) In AppEngine, what conditions are there upon a data type that will be forwarded to the client as the result of a service request, and why?