2014 09 24

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Politecnico di Milano – School of Informatics 090931 – Middleware Technologies for Dist. Sys. Prof. G. Cugola – September 24th, 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 PeriodicRunner that invokes a Runnable (passed as a parameter at instantiation time) every X milliseconds (a second parameter passed at instantiation time). The class provides a method void start()to start periodic invocation, and another method void stop() to stop it. After invoking the start method, method run of the runner is invoked (asynchronously) and invocation is repeated X ms after completion of the previous execution. This behaviour repeats until method stop is called. 2. Write in TinyOS a module Counter that periodically signals new values (integer numbers starting from 0 and incrementing at each step) . It provides a method to start it (passing the expected period) and to stop it. Write the interface and the implementation of the module (for the latter you may leverage the Timer<TMilli> module below). 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 remote camera. It allows to grab single images (1Mb in size) or to grab images periodically (in that case, images are pushed to the client every given seconds). 4. Write the OpenMP code (the minimal fr agment of code you need) that takes an array A of integers (of size NUM).and fills an array B (of floats) with the values B[i]=A[i]/MaxA (MaxA must be calculated as part of the provided code). 5. a) Describe MapReduce, in particular the two main phases and any additional…