2014 02 05

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Politecnico di Milano – School of Informatics 090931 – Middleware Technologies for Dist. Sys. Prof. G. Cugola – February 5th, 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 the PriorityMutex class. It looks like a pthread mutex but uses priorities to choose the thread to wakeup upon unlocking by the current owner . It offers the following methods: lock(int priority) which acquires the mut ex unless held by another thread , unlock() which releases the mutex, bool isLocked() which return s true if the mutex is already locked, otherwise acquires it and return false. The peculiarity of this mutex is that, upon unlocking, it gives access to (one a mong) the highest priority waiting threads. 2. Write in TinyOS a module that uses the Timer<TMilli> and Read<uint16_t> interfaces and implements the Listener interface (see below) to read the value of a temperature sensor every second, calculates the average value every ten reads and notifies the listener. 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(); } interface Listener { event void notify(uint16_t value) } 3. Write the CORBA interface for a printing server. It allows documents (characterized by a name and a sequence of bytes) to be printed (returning the job id), the list of jobs in queue to be read , and a specific job to be removed. It also allows to register a listener to be notified when a specific job (identified by its job id) completes. 4. Write the OpenMP code (the minimal fragment of code…