Comp150CPA: Clouds and Power-Aware Computing
Quiz 2 Answers -- April 27, 2011 -- Closed book
name: ____________________________ login: ______________
- (20 points)
Explain why an arbitrarily chosen key/value distributed hash
table is not automatically suitable for running Map/Reduce algorithms.
Answer: The main reason is that DHT's are optimized
for single fetches, and M/R requires collection and aggregation.
One can either optimize one's speed for single object fetches, or
optimize for collection of objects, and these require different design
- (20 points) Draw a BPMN diagram for the following situation:
a customer buys a scooter from scooters.com, which asks
a credit-card company to verify credit-card information,
after which it either voids the sale (if the credit card
is not good) or ships the scooter (if the sale is authorized).
Answer: an absolutely correct diagram is this one.
(Click to enlarge). It uses an event-based gateway to receive
the rejection, and a data-based gateway to send it, which is
realistic. I will accept anything close.
(20 points) Employees at a company work 35 hour weeks for a total cost
to the company of $100,000 a year each. Company sales average $1000/hour
on average during a regular work day. Based upon this, what is the cost
of an hour of downtime during working hours?
Answer: Let x be the number of employees. Then the cost
of downtime = work lost + revenue lost = $100,000*x/52/35 + $1000.
Each employee costs $100,000 (including benefits and social security/RRTA)
so that x employees cost $100,000x per year. There are 52 weeks in a year,
and 35 hours in a week, so the running cost per hour is $100,000/52/35.
- (40 points) Please fill in the blanks:
- Part of BPMN can be converted to BPEL by ____documenting or explaining____
the nature of communications between processes. Unlike BPEL, however,
BPMN also documents the behavior of ____personell/employee____
elements of the business, which cannot be documented in like manner.
- The reason that BPEL (and BPMN) are written in XML is not because
that is a human-friendly language, but rather, because XML has
pre-existing mechanisms for defining the ____types____
of XML fragments (using XSchemas) and for ____querying____
XML documents for desired keywords (using XPATH).
complexType in an Xschema describes an XML
element that contains ____other sub-elements____. An
Xschema restriction facet makes a text type match
____less (instances)____ than its base string type.
- The reason that Xschemas are used in implementing SOAP services
is to ____guard/protect____ against invalid data being
used as a SOAP query. This means that the code that implements
the service will ____execute/respond____ only if input matches.