2015 09 09

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Politecnico)di)Milano))Middleware)T echnologies)for)Distributed)Systems))) 09th)of)September)2015)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. •)Check the back of this page for any additional exercises. 1.)Implement in Java a PhotoBook class that organizes a (finite) set of photos and uploads them to a remote host so that they can be shared with others. Suppose a Photo class exists, together with a class SharingSvc that provides the following method: void upload(String bookTitle, Photo[] photos, String[] captions). Class PhotoBook provides a constructor that specifies the maximum number of photos in the book and the book’s title. It also provides the following methods: int add(Photo p) : this method adds a new photo in the book’s first empty slot and returns the slot number. It suspends the caller if the book is full. void setCaption(int slot, String caption) : this method sets the caption for the photo in the given slot. void upload(SharingSvc svc): this method uploads the entire book to the given sharing service and clears the book, leaving it ready to be filled again. Since the uploading operation may take a long time, method upload must operate asynchronously w.r.t. the caller (i.e., using a separate thread). 2.)In TinyOS write a module MaxRead that uses and implements the Read<uint16_t> interface. When requested to read a value from its clients, it reads the sensor wired to the Read<uint16_t> interface it uses 10 times (each read being interleaved from the previous one by 20ms) and returns the maximum value read. The following interfaces may help you: interface Timer<precision_tag> { command void startPeriodic(uint32_t dt); command void startOneShot(uint32_t dt);…