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Dipartimento di Elettronica, Informazione e Bioingegneria Politecnico di Milano Prof. Elisabetta Di Nitto and Matteo Rossi 20133 Milano (Italia) Piazza Leonardo da Vinci, 32 Tel. (39) 02-­2399.3400 Fax (39) 02-­2399.3411 Software Engineering II January 11th, 2019 Last Name First Name Id number (Matricola) Note 1. The exam is not valid if you do not fill in the above data. 2. Write your answers on these pages. Extra sheets will be ignored. You may use a pencil. 3. Incomprehensible hand-writing is equivalent to not providing an answer. 4. The use of any electronic apparatus (computer, cell phone, camera, etc.) is strictly forbidden. 5. You cannot keep a copy of the exam when you leave the room. 6. The exam is composed of three exercises. Read carefully all points in the text! 7. Total available time: 2h Scores of each question: Question 1 (MAX 7) ________ Question 2 (MAX 6) ________ Question 3 (MAX 3) ________ 2 Question 1 Alloy (7 points) Consider a load balancing component of a system, which creates and destroys instances of certain servers depending on the number of requests that are currently being handled by the system. Requests can be of various different types. For simplicity, let us say that there are three request types, Request1, Request2, and Request3, corresponding to the different services that can be handled by the servers. When instantiating a server, the load balancer can configure it so that it is able to handle some request types. In total, each server can handle, at the same time, at most 10 requests of any type. 1. Define the Alloy signatures that are necessary to model servers and the requests that they handle. 2. Using the signatures defined, formalize, through Alloy predicates, two of the following operations (we will grade only the first two…