2014 09 10

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Politecnico di Milano – School of Informatics 090931 – Middleware Technologies for Dist. Sys. Prof. G. Cugola – September 10th, 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 Barrier that allows a set of threads to all wait for each other to reach a common barrier point. In particular, it provides a method void await() throws InterruptedException that suspends the first N -1 caller until the last caller arrives. The number N is determined at barrier creation time (as a parameter of the constructor). An additional method void interrupt()exists that wakes-up the suspended threads returning them the InterruptedException. 2. Write in Ti nyOS a module that uses the Timer<TMilli> and Read<uint16_t> interfaces and implements the same Read<uint16_t> interface. It uses the Read interface twice. P eriodically (each second) it reads a value from each of the two interfaces it uses and calculates t heir average. When invoked through the Read interface it implements, it returns the last average value it calculated. 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 twitter like service. It allows to submit a new tweet, to search for tweets containing a specific hash word (returning the list of tweets that contain such word) and to register interest for tweets containing a specific hash word. In the latter case, when one of such tweets arives the interested client is notified. 4. Write the OpenMP code (the minimal…