NAME:_________________________________________ CMSC 435 midterm answers March 17, 2005
1
CMSC 435 midterm answers Sections 0301
Answer all questions in the space following each
question.
1 [7]. Security
a. What are the CIA attributes of security?
Confidentiality, Integrity, Availability
b. The 4 properties to ensure security are authentication,
authorization, data integrity and privacy. Define the role of
each.
Authentication – You are who you say you are.
Authorization – You have the rights to do what you want to
do
Data integrity- Data cannot be changed without your
knowledge
Privacy- Data cannot be seen by others without your
knowledge.
2 [10]. For each statement below, tell whether it is a good
requirement or not and why.
a. The system shall be easy to use.
No - What is “easy?”
b. The system shall respond in less than 2 seconds with the
answer.
Yes – Explicit requirement which can be tested.
c. The system may handle files of up to 2 MB in size.
No – “May” is optional so not really a requirement.
d. The system shall conform to all requirements of IEEE
standard 854.
Yes – Assuming IEEE 854 is an explicit set of requirements.
e. The system shall operate on all web browsers.
No – “All” is too vague here.
3. [30] Explain each of the following in 1 or 2 sentences.
a. (High, Low) __High__ cohesion is preferred. Why?
Want operations in a module to be interrelated.
b. (High, Low) ____Low___ coupling is preferred. Why?
Minimize interactions between modules allows for easy
changes.
c. What is glue code?
Code to allow premade packages (e.g., COTS tools) to be
embedded within another system.
d. RMA attributes are sometimes used as the name for
dependability. What does RMA stand for?
Reliability, Maintainability, Availability.
e. Why is dependability considered a non-functional
requirement?
It’s a property of a system, not an explicit function, such as
safety, security, reliability.
f. Give another dependability attribute, besides the RMA
ones, and why is it also non-functional?
Security – No explicit in-out relationship. System has to
implement the CIA attributes of question 1.
Also safety, usability, almost any other”…ililty.”
g. Eclipse is a (framework, reference model, architecture)
__framework__ and why?
It is a system that runs that allows other tools to be plugged
into it.
h. The ECMA “toaster” model is a (framework, reference
model, architecture) __reference model_ and why?
It defines the areas where standards are needed to define the
interfaces between tools and the environment framework.
i. The Rayleigh curve is a theoretical curve useful to model
what attribute of a project?
Cost (or effort) on a project as a function of time.
j. What are the differences between an error, a fault, and a
failure?
Failure – Observed misbehavior of a system.
Fault – Place in code that causes failure.
Error – Place in code that is incorrect. (Not necessarily the
fault.)
4. [12] For each of the follow, does it represent a risk and
why?
1. You didn’t study for this midterm and you think you may
fail.
Risk – Cost is low grade and probability is between 0 and
100 that you may fail, but not guaranteed. You may
remember enough to pass.
