1. EEC-681/781 Distributed Computing Systems Discussion#1 (Chapter 1&2) Wenbing Zhao wenbing@ieee.org

2. 2 Q1: What is the role of middleware in a distributed system? Fall Semester 2008EEC-681: Distributed Computing SystemsWenbing Zhao

3. 3 Q2: Explain what is meant by (distribution) transparency, and give examples of different types of transparency. Fall Semester 2008EEC-681: Distributed Computing SystemsWenbing Zhao

4. 4 Q3: Why is it sometimes so hard to hide the occurrence and recovery from failures in a distributed system? Fall Semester 2008EEC-681: Distributed Computing SystemsWenbing Zhao

5. 5 Q4: Why is it not always a good idea to aim at implementing the highest degree of transparency possible? Fall Semester 2008EEC-681: Distributed Computing SystemsWenbing Zhao

6. 6 Q5: What is an open distributed system and what benefits does openness provide? Fall Semester 2008EEC-681: Distributed Computing SystemsWenbing Zhao

7. 7 Q6: Describe precisely what is meant by a scalable system. Fall Semester 2008EEC-681: Distributed Computing SystemsWenbing Zhao

8. 8 Q7: Scalability can be achieved by applying different techniques. What are these techniques? Fall Semester 2008EEC-681: Distributed Computing SystemsWenbing Zhao

9. 9 Q8: What is the difference between a vertical distribution and a horizontal distribution? Fall Semester 2008EEC-681: Distributed Computing SystemsWenbing Zhao

10. 10 Q9: Why are transport-level communication services often inappropriate for building distributed applications? Fall Semester 2008EEC-681: Distributed Computing SystemsWenbing Zhao

11. 11 Q10: Suppose you could make use of only transient synchronous communication primitives. How would you implement primitives for transient asynchronous communication? Fall Semester 2008EEC-681: Distributed Computing SystemsWenbing Zhao

12. 12 Q11: Explain why transient synchronous communication has inherent scalability problems, and how these could be solved. Fall Semester 2008EEC-681: Distributed Computing SystemsWenbing Zhao

13. 13 Fall Semester 2008EEC-681: Distributed Computing SystemsWenbing Zhao Q12. The most prominent benefit of the publish/subscribe model is the increased scalability if the number of consumers per message (created by a producer) is large. Understand this benefit by comparing the number of transport-level messages needed to propagate an application-level message to, say, 3 consumers, using the two different messaging models (queue-based and publish/subscribe).