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Analysis Of 622 Distributed Software Engineering ( Fall 16 )

Decent Essays

SWE 622 Distributed Software Engineering (Fall 16) Reading Assignment 4 Team Members: Bobby Bounvichit G00544954 Damaruka Priya Ulla G00964073 Mukesh Kumar Sunder G00973428 Zain Usmani G00738248 1. Consider 5 processes that need to agree on their joint state. To protect against Byzantine failures, the processes adopted a protocol as described in the slides, in particular, each process broadcasts its own state to all others, assembles the state received from others, and then broadcasts its view of the full state to all others. Suppose that, after this, process 1 receives the information provided below. Identify the process(es) that have Byzantine failure, if any, based on this data. Briefly justify your answer. From 2 got (3,4,1,5,8) From 3 got (3,3,1,6,8) From 4 got (3,1,1,5,8) From 5 got (3,2,1,5,8) At this point Process 1 has received all the collected data from all the other processes. We can see that all processes received 3 from process 1. All Processes received a different number from process 2, making it a possible Byzantine failure. From process 3, all processes received 1. From process 4, majority received 5 from process 4, except process 3, which received a 6, making process 4 a possible Byzantine failure. All processes received 8 from Process 5. So the unknown values would be from Process 2, and Process 4. 2. What is the difference between predictability and consistency in distributed software systems? Predictability has to do with knowing

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