Software Architecture Problem set

1. The Kingdom of Bhutan measures the happiness of its population, and government policy is formulated to increase Bhutans GNH (gross national happiness). Read about how the GNH is measured (try www.grossnationalhappiness.com) and then sketch a general scenario for the quality attribute of happiness that will let you express concrete happiness requirements for a software system implementing GNH.
2. Author James Gleick (A Bug and a Crash, www.around.com/ariane.html) writes that It took the European Space Agency 10 years and $7 billion to produce Ariane 5, a giant rocket capable of hurling a pair of three-ton satellites into orbit with each launch. All it took to explode that rocket less than a minute into its maiden voyage was a small computer program trying to stuff a 64-bit number into a 16-bit space. One bug, one crash. Of all the careless lines of code recorded in the annals of computer science, this one may stand as the most devastatingly efficient. Write a safety scenario that addresses the Ariane 5 disaster and discuss tactics that might have prevented it.
3. One of the most sophisticated attacks on record was carried out by a virus known as Stuxnet. Stuxnet first appeared in 2009 but became widely known in 2011. Read about Stuxnet and see if you can devise a defense strategy against it based on the tactics discussed in this class.
4. Web-based systems often use proxy servers, which are the first element of the system to receive a request from a client (such as your browser). Proxy servers can serve up often-requested web pages, such as a companys home page, without bothering the real application servers that carry out transactions. There may be many proxy servers, and they are often located geographically close to large user communities, to decrease response time for routine requests. What performance tactics do you see at work here?
5. Once an intermediary has been introduced into an architecture, some modules may attempt to circumvent it, either inadvertently (because they are not aware of the intermediary) or intentionally (for performance, for convenience, or out of habit). Discuss some architectural means to prevent inadvertent circumvention of an intermediary.