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Question 1
1. Why do we need to conduct a demand analysis? What are the usual requirements for software systems?
Answer: (1) In order to develop a software product that truly meets the needs of users, you must first know the needs of users. An in-depth understanding of software requirements is a prerequisite for the success of software development. No matter how well we do design and coding work, programs that cannot truly meet user needs will only disappoint users and bring troubles to developers.
(2) Determine the comprehensive requirements for the system: 1. Functional requirements; 2. Performance requirements; 3. Reliability and availability requirements; 4. Error handling requirements; 5. Interface requirements; 6. Constraints; 7. Reverse requirements; 8. The requirements that can be put forward in the future, analyze the data requirements of the system.
Question 2
2. How to effectively communicate with users to obtain the real needs of users?
Answer: The method of communicating with users to obtain requirements: interviews; data flow-oriented top-down refinement; simple application specification technology; rapid establishment of software prototypes
Question 3
3. The working process of the bank's computer savings system is roughly as follows: The deposit or withdrawal form filled out by the depositor is entered into the system by the clerk. If it is a deposit, the system records the depositor's name, address (or telephone number), ID number, deposit type, Deposit date, expiration date, interest rate and password (optional) and other information, and print out the deposit slip to the depositor; if it is a withdrawal and the password is left when depositing, the system will first check the depositor password, if the password is correct or the password is not left when depositing , The system calculates the interest and prints out the interest list to the depositor.
Use the data flow diagram to describe the functions of the system, and use the entity-connection diagram to describe the data objects in the system.
Question 4
4. Analyze the air ticket reservation system described in the 3rd question of exercise 2. The trial entity-connection diagram depicts the data objects in the system and the data flow diagram depicts the functions of the system.
Question 5
5. Analyze the patient monitoring system described in Question 4 of Exercise 2. Try the entity-connection diagram to describe the data objects in the system and use the data flow diagram to describe the functions of the system, and draw the top-level IPO diagram of the system.
Question 6
6. The working process of the copier is roughly as follows: it is in the idle state when it has not received a copy command, and enters the copy state once it receives a copy command, and returns to the idle state after completing the work specified by a copy command, waiting for the next copy command; if If there is no paper when executing the copy command, it will enter the out of paper state, give a warning, wait for paper to be loaded, and enter the idle state after full paper, ready to receive the copy command; if a paper jam occurs during copying, it will enter the paper jam state and issue a warning Wait for the maintenance personnel to troubleshoot, and return to the idle state after the trouble is eliminated.
The trial state transition diagram depicts the behavior of the copier.
Answer: It can be seen from the problem statement that the status of the copier mainly includes "idle", "copying", "out of paper" and "paper jam". The events that cause the status transition are mainly "copy command", "copy command completed", "out of paper found", "full paper", "paper jam fault occurred" and "paper jam fault eliminated".
