COMP 290 Midterm Exam Spring 2002 There are 4 questions answer all of them If you need to make an assumption to clarify a problem write your assumption down Only reasonable assumptions get full credit Explain all answers You hav e two hours to nish the exam The questions are of varying dif culty so it is probably advisable to answer the easier questions rst to avoid getting stuck on the harder ones Good Luck 1 2 Name your favourite sub area in ubiquitous computing 1 pt Scope Applications and Issues 33 pts a Give three features of a ubiquitous computing environment that you do not nd in a traditional computing environment 6pts b Motivate the features in a by describing two classes of applications enabled by each feature and giving a concrete example of each class 15pts c Give two new research issues raised by each of the features in a 12pts 3 Merging 33 pts a Explain the problem of merging replicas 5 pts b Give two con icting requirements an ideal merging infrastructure should satisfy Explain why they are con icting 11 pts c Describe three different approaches e g Coda Bayou Sync for addressing these require ments and compare them based on how well they satisfy the requirements 17 pts 4 Service Discovery 33 pts a Explain the service discovery problem identifying why traditional schemes such as DNS do not solve this problem 7 pts b Distinguish between push and pull based service discovery explaining why systems such as UPnP support both 8 pts c Berkeley s SDS and MIT s INS both create multiple name servers to support service discovery Describe and compare the interaction among the name servers in the two approaches 18 pts
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