Sequence Diagrams And Object Constraint Language

Discuss about the Sequence Diagrams and Object Constraint Language.

For completing the study, the sequence diagram has been selected. The sequence diagram is a dynamic UML modeling solution (Nanthaamornphong et al., 2015). This diagram concentrates on the objects and processes. UML is the abbreviation of Unified Modeling Language. This modeling language assist the software designers to gather and present the aspects of proposed system.

The study includes the description of the Collin’s car parking system. In addition to that, the study presents three sequence diagram of three sub systems of car parking system. The proposed sequence diagram is created based on three important use case of the parking system.

The system is a car parking system for Collin. It has been assumed that the car parking system is going to be implemented in the premise of parking area. The system will be handling two types of customers. The system will be categorizing customers based on the tickets they have purchased. The fixed customer will buy seasonal tickets. On the other hand, the ordinary customer will buy tickets every time they will request for parking car. Six types of seasonal tickets are available at the parking. The fixed customer can buy tickets for one year, six months, quarter of a year, one month, two weeks and one week. There is no exception in ticket processes. The ordinary tickets are charged with different prices based on the time parking request is submitted as well as the day. The charges are generally high during weekends.

The system has various devices connected to it. Each of the devices are connected to the core system. A database is also connected with the system so that all the required data can be stored for business purposes. The system will not hold the records of the customer who purchases ordinary ticket, but fixed customer information are registered into the system.

The system has mainly five components that are integral part of the daily process. The sensors are the smallest part of the system which are installed within the pillars. These sensors recognize any approaching car toward the gate. The sensor sends the signal to the core system and the system generates an output on the display. All the IoT devices installed in the pillars are connected to a microcontroller. This microcontroller handles the processes of the IoT and communicate with the main system. The display in the pillar acts as the communication medium between the customers and the system. The customer input the details, required to park the car, and the system process those inputs to generate a result. The display will show a message after every action to let the customer know whether the process is successful or not.

Ticket Checking Subsystem

The ticket generator and ticket checker are integral part of the system. The ticket generator works independently and only takes input from the core system. The system only sends Boolean values and ticket code to the ticket generator. The ticket generator prints the code of the ticket and the date on which it is created. The barriers are also a part of the system. The parking system uses standard barriers that can operate on their own, that means these have own microcontroller. The system only sends a signal to the barrier and the barrier rises or closes as per the signal request. As the whole system is runs automatically, the use of the good quality of microcontroller is recommended. Good quality microcontrollers can work very fast and effectively on their own and generate desired results. The system can process other operations at that time which will result in not only quicker response to user request but also better service.

There is an actor and three objects in the sequence diagram. The user first, insert the ticket. The system then checks that whether the ticket is valid or not. The system does it by calling the method defined as ValidateUser. In this method, the system matches that the unique number printed on ticket is available or not. If the number exists, then system checks whether the ticket has expired. If all the things go in the right path, then the system allows the user to enter into the parking area. This sequence diagram is generated based on reach parking gate. In case one of the two checking, the outcome is negative, then the system will cancel the parking request. The fixed customer will insert their ticket as soon as they will appear in front of the pillars. The general customer, on the other hand, will buy a ticket first and then insert the purchased ticket. Both the customer will be exiting the parking area by inserting the cards into the exit pillar ticket checking tool. The system will return the tickets to the fixed customer. The general tickets will not be returned.

The customer verification process is a very essential aspect of the system as shown in the figure 2 sequence diagram. The system prevents the unauthorized users to enter into the system by implementing good quality authentication process. The main purpose of authentication process is that the system will allow access to internal information to registered or intended users only. The authorization is the next phase of validation. This technique validates that the user has the power to access the requested information or process. These two processes vary system to system. Some systems use user id password, some use access cards. This parking system will execute both the authentication and authorization process based on the ticket.

Ticket Purchase Subsystem

The system must be easy to use and understand. The system must provide all the options to the users in the simplest way. The system sequence diagram shows that the system process of ticket checking will be triggered by inserting ticket into the ticket checker. As new customers will appear to the parking area for parking their car, it is very essential to focus on the usability of the parking system. The interface of the system has to be very user friendly. The navigation must be completely one click way. The user must click one time to get to the result. The interface will only show the necessary options on the screen.

The proposed sequence diagram is consisted of seven classes. The customer calls start the process by selecting option of buying tickets. Before that, the system automatically shows various options on screen as soon as the car arrives in in front of the pillars. The customer chooses to buy ticket and then the system asks for making payment. As the sequence diagram represents payment through card, the customer enters the card into card processor and makes the payment. Now, the processor checks whether the card and pin number is valid or not. If the card and pin are valid then the system checks whether user account has sufficient balance. If the fund is available, the bank automatically transfers requested amount. After receiving the payment, the system generates the tickets and provide the ticket to the user. In case sufficed balance is not available, then the system rejects the request and shows the reason of rejecting.

The information gathering, storing and retrieving is an integral part of the system that helps the system to execute daily operations. The system will have a loud based database connected to it. As there will be twenty car parks, each of the park will access the same database. This way, the system can identify which parking area has free space. This will result into increased customer satisfaction. The system will use Oracle database software to manage the database. The reason behind choosing the oracle is that this vendor provides strong security and the service is very good. The system will have a separate core to handle the database software so that option of comprising performance of the system has not to be considered. As the sequence diagram shows, the system must store the data collected from the user so that these data can be used in future. However, losing important data or data corruption is not a new term in the ICT domain. The system will be connected to data backup/recovery system.

The proposed sequence diagram specially shows the classes and processes related to payment process. The payment sequence diagram has six processes. The user first, insert their card into the system. The system read the credit or debit card and validate it. After the card is validate, the interface shows option of making payment to the user. The user selects the payment function. As the pin verification mandatory, the system instantly shows the pin request. After the user enters the pin, the system connects with consortium, which transfer the user card data to bank and bank verifies the card. The user then input the amount or confirm the ticket option (it has not shown clearly as this assumption will be made in interface design part of the project). Then the consortium communicates with bank and update the user account details. The system also shows the message of payment successful.

Payment is a very important part of the system. Through this process, the Collin’s parking system will generate profit. The system will accept various types of cards. As the system already hold the data of ticket price and no other data need to be stored for cash payment, the system will not store any additional record of cash payment. In terms of car payment, the system will store the card number, cvv and card holder name. This will allow the system to generate a receipt for payment. This will be helpful, if the system does not receive the payment but money is reduced from the customer’s account.

Conclusion:

From the above study it can be concluded that the proposed sequence diagrams have successfully visualized the desired subsystems. Through the sequence diagram, the processes and connection between the objects can be seen clearly. The diagrams are so clear and easy to understand that generating the class diagram using the sequence diagram will not be a big issue. The description of the sequence diagrams has filled the gaps where some parts were critical to understand. Collin’s car park system is a complete parking system that can handle almost all the processes automatically. The sequence diagram has presented it successfully. All the three diagrams represent that only the customer’s intervention is required to complete the parking processes. However, the system will have a admin who can track and control all the processes but that aspect of the system not included within the case study.

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