Solutions exercises instruction 1

Transcription

1 Solutions exercises instruction 1 1. The re-formulated requirements, together with a motivation: a) First of all, shall be able should be avoided. Second of all, according to the syntax, we should have for this requirement [Subject][Action][Object][Constraint]. So, we could reformulate the requirement as follows: The system [Subject] shall process [Action] executing jobs [Object] at a load of at least 40 simultaneous jobs [Constraint]. b) The resource provider is an actor and should be mentioned in the attributes of the requirement, not in the requirement itself. A reformulation of the requirement is the following: The system [Subject] shall support [Action] the visualisation of resourceproject relations [Object]. c) This requirement has the same issue as the previous requirement. A reformulation: The system [Subject] shall allow [Action] system administrator commands [Object] on computers running Windows XP, Mac OS X, or Linux [Constraint]. Note that it could be argued whether the version of Mac OS X and Linux must be part of the constraint. d) This is a requirement about a non-capability and about user friendliness. This requirement is not veriable, because it is not measurable. We could try something like this: Once the software is installed [Condition], the system [Subject] shall uninstall [Action] the software [Object] after at most 2 user mouse clicks [Constraint]. 1

2 2. For each requirement, the analysis follows. a) Any standard computer is a vague statement. What is standard? Do you mean every computer connected to the CERN network? Also, it is in the passive form. A better formulation would be: The upgraded management system [Subject] shall give access [Action] of the information stored in the database [Object] to all computers connected to the CERN network [Constraint]. This new formulation is verifiable. b) The requirement is not about the management system, but about people giving car stickers. A better formulation would be: The upgraded management system [Subject] shall create [Action] car stickers [Object] only to users with a valid CERN ID. However, it is hard to verify, because it seems that the check for a valid ID is made by a person and not the system. c) Under normal conditions is not precise enough. A better formulation would be: The software [Subject] shall open [Action] in less than 3-4 seconds [Constraint]. d) There are more than one requirements in this one. Also, they are not system centric. Also, the second part is not about the system. A better formulation would be: R1: The sytem [Subject] shall give access [Action] to French-English dictionnary [Object]. R2: The system [Subject] shall support [Action] services [Object]. The rest is part of the attributes of the requirement. e) Requirements must not use will. Also, 24/7 is vague. A better formulation would be: The system [Subject] shall run [Action] at a reliability level of 99,99% [Constraint]. 2

3 Someone should of course define reliability level. 3. Step 1: identify the system - LIS software Step 2: read the text and try if each sentence gives rise to one or more requirements. The LIS is capable of running on various commonly used operating systems (Windows, UNIX, Mac OS X, etc.) and is easy to maintain. Here, there two requirements possible: (1) which systems must be supported and (2) easy maintenance. System compatibilities: is it an essential aspect? R1: The LIS system shall run on the following operating systems: Windows 8, Mac OS X from 10.11, Ubuntu version XX, Red Hat Enterprise... It is important to make the list of possible systems explicit. Easy maintenance is too vague and cannot be a requirement. translate this in terms of costs: We can try to R2: The LIS system shall be maintainable at a yearly cost of at most 0,2 million Euros. The library lends books and magazines to borrowers, who are registered in the system, as are the books and magazines. There are two types of objects in the system: R3: The LIS system shall support the registration of books, magazines, and borrowers. The library handles the purchase of new titles for the library. This does not say anything about the system. Should the purchase be done via the LIS system? Assume that this is the case: R4: The system shall support the purchase of titles. Popular titles are bought in multiple copies. Old books, and magazines are removed when they are out of date or on poor condition. We can add the option for multiple copies: 3

4 R5: The system shall support the buying of titles in one or multiple copies. We can also add the remove features (is the deletion permanent?): R6: The system shall support the declaration of attributes out-of-date and poor condition to a title copy. R7: When a title has attribute out-of-date or poor condition, the system shall remove the copy. LIS should support two kinds of users: librarians and borrowers. This is a clear requirement. R8: The LIS system shall support users of two kinds: librarians and borrowers. Librarians can create, update, and delete information about library copies. They can also generate a report about borrowers and about copies in the LIS. For this, we update the requirement R3 expressed earlier. R3: The LIS system shall support the creation, update, and deletion of information about library copies and borrowers by librarians. R9: The LIS system shall support the generation of reports about library copies and borrowers by librarians. A borrower is a library user who can make a loan of a copy of a title that is part of the library holdings. A borrower can also reserve a book or magazine that is not currently available in the library, so that when it is returned or acquired by the library, that person is notified. These are clear statements about the capabilities of borrowers. However, these depend on previously undefined attributes of a title: The system shall support the declaration of attributes available and not available to a copy. The system shall support the declaration of attributes reserved and not reserved to a copy. Now, we can use the new attributes. 4

5 R10: When a copy has attribute available and not reserved, a borrower can create a loan, changing the available attribute to not available. R11: When a copy has attribute not available and not reserved, a borrower can reserve the copy, changing the not reserved attribute to reserved. R12: When a copy has attribute reserved and obtains the attribute available, the LIS system shall notify the reserving borrower by e- mail. The reservation is canceled when the borrower checks out the book or magazine or through an explicit canceling procedure. Two operations are described here, that both affect the title copy attributes. We split these in two separate requirements. R13: When a copy has attribute available and reserved, the reserving borrower can check out the copy, changing its available attribute to not available and its reserved attribute to not reserved. When a copy has attribute reserved, the reserving borrower can cancel the reservation, changing the reserved attribute of the copy to not reserved. Librarians and borrowers make requests and interact with the LIS through a library kiosk (a computer interface). This is a clear statement. R14: The LIS system shall have a library kiosk (computer interface), through which all interactions can be performed. Loans and returns of library material are processed using an ID scanner. This should be explicitly stated as a technical requirement of the LIS system. R15: The LIS system shall provide an ID scanner to process loans and returns of a copy The use case diagram: 5

6 4.2. Detailed description of the use case Reserve a copy: Pre-conditions: True. Trigger: a borrower wishes to reserve a copy. Guarantee: the borrower has reserved the copy. Main scenario: 1. The borrower checks whether the title is available. 2. The borrower checks if the status of at least one copy is not reserved. 3. The borrower sets the status of one copy to reserved. Alternatives: 6

7 2.a. The title is not available. The borrower sets its status to reserved. 3.a. No copy has its status set to not reserved. The reservation is aborted Requirement R11 is related to this use case The use case diagram: 5.2. Detailed use case descriptions: Shop for a book: Pre-condition: True. Trigger: The user searches for a title to buy. Guarantee: The user buys a book and the price of the book is transferred to the bookshop bank account. Main scenario: 1. The user searches for a title. 2. The bookshop presents the prices for available copies of the book. 3. The user chooses a copy. 4. The user gives his/her credit card info. 5. The system reserves the copy for the user and submits a request (including credit card info & price) to the bank. 6. Upon a successful authorization from the bank, the copy is sent to shipment. 7

8 Alternatives: 2.a. If no copy from the title is available, the user receives an error message. 6.a. If the credit card authorization fails, the reservation is cancelled and the user receives an error message. Add copies: Pre-condition: True. Trigger: The owner adds copies to the stock. Guarantee: The copies are added to the stock. Main scenario: 1. The owner adds copies to the stock. 2. The owner enters prices for the new copies. 3. The number of available copies is updated. item[5.3.1.] Use case diagram: Detailed use case of transport goods: Pre-condition: True. Trigger: The client submits a transportation request. Guarantee: The package is scheduled for transportation and the price is transferred to the company bank account. 8

9 Main scenario: 1. The client submits a request specifying the size, source, and the destination of the package. 2. The company finds the next available vehicle which can accomodate the package. 3. The company makes an invoice based on the duration of the trip and sends it to the client. 4. The client agrees with the terms of the offer and gives his/her bank account number and an authorization to transfer the money to the company bank account. 5. The company forwards the authorization to the bank. 6. The money transfer is completed and the transportation is scheduled. Alternatives: 2.a. If the company does not find a suitable vehicle, the client receives an error message. 4.a. If the client does not agree with the terms of the offer, the request is cancelled. 6.a. If the transfer fails, the client receives an error message and the request is cancelled. 6.b. If the vehicle is reserved for another transportation, steps 2-6 are repeated. 9