31 08 17t

Page 1

Dipartimento di Elettronica, Informazione e Bioingegneria Politecnico di Milano Prof. Elisabetta Di Nitto, Luca Mottola 20133 Milano (Italia) Piazza Leonardo da Vinci, 32 Tel. (39) 02-­2399.3400 Fax (39) 02-­2399.3411 Software Engineering II August 31, 2017 Last Name First Name Id number (Matricola) Note 1. The exam is not valid if you don’t fill in the above data. 2. Write your answers on these pages. Extra sheets will be ignored. You m ay 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 w hen you leave the room . 2 Question 1 Alloy (8 points) A computer’s memory can be modeled in Alloy based on the following signatures: sig Address {} sig Value {} sig Computer { memory: Address -> lone Value } Using Alloy, you are to: 1) define a fact that states that the memory of the computer is never empty, that is, at least one memory address exists that is not uninitialized 2) model the behavior of predicate delete [c: Computer, addr: Address, c': Computer] such that memory at address addr becomes uninitialized 3) model the behavior of predicate move [c: Computer, oldAddr: Address, newAddr: Address, c': Computer] such that, if a value exists in address oldAddr and newAddr is uninitialized, the value is moved to newAddr and oldAddr becomes uninitialized; nothing changes if oldAddr is uninitialized 4) change the signatures above to extend the model to the case of a computer with multiple independent memory segments 3 4 5 Questions 2 JEE (4 points) A simple online store uses JEE to handle warehouse state and user purchases. Administrators can manipulate the information in the database using the AdminBean…