2014 07 01

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1. Politecnico di Milano – School of Informatics 090931 – Middleware Technologies for Dist. Sys. Prof. G. Cugola – July 1st, 2014 Rules:  You are not allowed to use books, notes, or other material.  You can answer in Italian or English.  Total time for the test: 1.5 hours. 1. Implement in Java a class Mutex that provides methods void lock() , void unlock() , and boolean tryLock() with the same semantics of the equivalent functions provided by the pthread C library. Use only the base synchronization features provided by Java. 2. Write in TinyOS a module that uses the Timer<TMilli> and Read<uint16_t> interfaces and implements the same Read<uint16_t> interface. When asked to read a value it invokes the read operation three times in a row ( separating them by at least on e tenth of a second) and returns the average of the three values read. interface Read<val_t> { command error_t read(); event void readDone( error_t result, val_t val ); } interface Timer<precision_tag> { command void startPeriodic(uint32_t dt); command void startOneShot(uint32_t dt); command void stop(); event void fired(); } 3. Write the CORBA interface for a shared printer. It allows to submit a new job (passing the document as a blob of data), list the waiting jobs, remove a job and being notified when a given job is printed. 4. Write the OpenMP code (the minimal fragment of code you need) to count the number of positive elements in an array of int data1 (of size NUM). 5. a) Describe the different steps of the Hadoop map -reduce impleme ntation, and if any of them could be a bottleneck during a job execution (and why). b) Suppose you are maintaining several online magazines and blogs, in which you can have articles and each article has multiple comments. Each comment has (at least) an aut hor, the…