System model hierarchy model is a set of components and relationships. The relationship indicates dataflow between the sub-systems. Here the electronic library card system is a system where we have the member should have an electronic library card in order to borrow a book. This card contains information such as member ID, name, address, expiry date for member.
The inputs taken from external environment are the user and electronic card.
The sub components are the sensor components, actuator components, computation components, communication components, coordination components and user interface components. Emergent property is known only when all the component of the system is assembled. So, the emergent property of this library system is borrowing of book.
Relationship between the components such as date of borrows and date of return.
Integration of component is if the date of borrow exceeds date of return then a fine is charged.
The system consists both of functional properties and no-functional properties. Functional property which is physical or tangible, example; renew the book borrowed.
Non-functional property is the reliability, performance, safety and security of the library system.
Reliability: it will not allow intruder to enter the system using the electronic card, as it verifies if the member exists or already expired.
Performance: the user can search for the books he want and if not available will generate a message to indicate when the book will be available, that is the date on which the previous user I supposed to return it.
Safety: If the user already has a book where the return date is already exceeding, then the member is reliable to pay a fine in order to proceed with further borrowing.
Security: The membership card consists of a security code which only the user knows. In case of lost of the code, the system is automatically blocked the access of the member which possess this card.
1. Sensor Components
It collects information from the system’s environment. The sensor component here is the electronic card where a barcode scanner is used to detect the user and allow access.
2. Actuator Components
These components cause some changes in the system environment. Here, member can search for book he needs to borrow only after the system verifies whether he has a book in due before proceeding. In the case, where the searched book is not available, the date of availability of the book is indicated.
3. Computation Components
Here on the on various inputs computations are performed to result in various outputs.
If the borrow date exceeds the return date, then a fine is calculated on a prorata depending on the number of exceeding number of days.
Example: Due date was on 15 Oct 2007 and the book was returned on the 21 Oct 2007, then the exceeding number of days is 7.
Fine for 1 day = Rs50
In that case, Fine = 7*50 = Rs350.
A receipt with indication of the number of exceeding days, the amount to be paid and a details on the books such as book title, author’s name, due date for return and information about the member is processed.
4. Communication Components
Communication components allow other system components to communicate with each other.
After scanning the electronic card, the access control will generate a message: “Access granted” or “Access denied”.
If a user already has a book due, the system will here too generate a message to alter the borrowing procedure.
5. Coordination Components
These components coordinate the operation of other components.
After the member has selected his books, the useful information such as Member ID, date of borrows title of books taken and date of return will be stored in the library database for this specific member.
And thus these data are also stored on the electronic card through the barcode process.
6. Interface Components
Interface components transform the representation used by one system component into a representation used by another component.
Here this digital information is generated into human language English or French. The information about date of borrow and return date is indicated to the user with a print out which is tagged on the book.
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