Agenda J.N.Kotuba SYST Object Oriented Methodologies 2 Assignment No 1 posted Review details SLATE-Weekly Topical Outline and Schedule modified Recap last lesson Learning outcomes for today Develop the requirements model & the Unified Process Use cases Use case diagrams Use case narratives
Last Class J.N.Kotuba SYST Object Oriented Methodologies 3 Introduced Unified Modeling Language (UML) Discussed Models Tools Techniques
Objectives for today J.N.Kotuba SYST Object Oriented Methodologies 5 Explain the difference between the Waterfall SDLC and the unified process Learn how to use the Event Table Technique to identify use cases Learn how to construct a use case diagram Learn how to build a use case narrative for each use case and why the narratives are important Be able to explain the difference between the system boundary and the automation boundary
The Unified Process J.N.Kotuba SYST Object Oriented Methodologies 6 Four key stages. Inception. Elaboration Construction Transition
Unified Process:Inception J.N.Kotuba SYST Object Oriented Methodologies 7 Go ahead on project. Scope determined. Business case developed for project.
Unified Process: Elaboration J.N.Kotuba SYST Object Oriented Methodologies 8 Basic architecture of the system developed. Construction plan is approved. Risks are identified.
Unified Process: Construction. J.N.Kotuba SYST Object Oriented Methodologies 9 Iterative approach to developing software. Product will be a beta.
Unified Process:Transition J.N.Kotuba SYST Object Oriented Methodologies 10 Beta product is introduced to users and information is collected from users during roll-out.
Iterative Development J.N.Kotuba SYST Object Oriented Methodologies 11
Modeling J.N.Kotuba SYST Object Oriented Methodologies 12 Software development is the production of ‘executable models’. These models often are abstractions of the original problem with classes added to solve the user’s problems.
Different Types of Models J.N.Kotuba SYST Object Oriented Methodologies 13 Use Case Model. The system from the users point of view. Static Model. The elements of the system and how they relate to one another. Dynamic Model. Outlines the behaviour of the system in the context of Object interactions.
UML J.N.Kotuba SYST Object Oriented Methodologies 14 The Unified Modeling language is (UML) a language for development object-oriented models and system designs. It provides a complete set of graphical diagrams to specify use cases, class diagrams and the dynamic model (object interactions) of a system. Can be used with different programming languages.
System Boundary vs Automation Boundary J.N.Kotuba SYST Object Oriented Methodologies 15
J.N.Kotuba SYST Object Oriented Methodologies 16 System Boundary vs Automation Boundary
Use Case Model A use case is a script: A step-by-step description of how a user might make use of the system to do a task It is a “case of the usage of the system.” 17
User Goals, Events, and Use Cases Use Case -- An activity the system performs in response to a user request Techniques for identifying use cases User goal technique Each goal at the elementary business process (EBP) level is a use case EBP – a task performed by one user, in one place in response to a business event, that adds measurable business value, and leaves system and data in consistent state 18
User Goals, Events, and Use Cases (continued) CRUD analysis technique (create, read, update, delete) Event decomposition technique 19
Event Decomposition Technique Event – an occurrence at a specific time and place and which needs to be remembered Business events trigger elementary business processes (EBPs) EBPs are at correct level of analysis for use cases Identify business events to decompose system into activities/use cases 24
Types of Events External Outside system Initiated by external agent or actor Temporal Occur as result of reaching a point in time Based on system deadlines State Something inside system triggers processing need 25
Identifying Events Can be difficult to determine Often confused with conditions and responses May be useful to trace a transaction’s life cycle Certain events left to design phase System controls to protect system integrity Perfect technology assumption defers events 30
Sequence of Actions that Lead Up to Only One Event Affecting the System 31
Sequence of “Transactions” for One Specific Customer Resulting in Many Events 32
Identifying the Actors J.N.Kotuba SYST Object Oriented Methodologies 36 Where do you look? Context Diagram Existing system documentation (our case) Ask the following questions Who or what provides inputs,such as forms, voice commands, fields on input screens, etc to the system? Who or what receives outputs, such as notifications, reports, voice messages, etc from the system? Are interfaces required to other systems? Are there any events that are automatically triggered at a predetermined time? Who (User) will maintain the information system?
Use Case - Actors J.N.Kotuba SYST Object Oriented Methodologies 37 An actor is always outside the automation boundary of the system but may be part of the manual portion of the system an actor is not always the same as the source of the event in the event table. A source of an event is the initiating person, such as a customer, and is always external to the system, including the manual system. an actor in use case analysis is the person who is actually interacting (hands-on) with the computer system itself.
Use Case Identifies What Users Want J.N.Kotuba SYST Object Oriented Methodologies 38 Use cases focus on usage of the system Services Behaviors Responses No internal structural details of the system Can be considered as the “responsibilities” of the system
Use Case Identifies What Users Want Next Validate use case names Write narrative descriptions for each use case Refining the name May “discover” more than one use case E.g register member Register new member Renew existing member Purchase Retail Trade Dealer staff J.N.Kotuba 39 SYST Object Oriented Methodologies
Use Case Identifies What Users Want J.N.Kotuba SYST Object Oriented Methodologies 40 Refining the name Does it tell the whole story? Any exceptions? Special cases? Possible errors? Occasional variations? Does the name cover several related or similar processes? Is there a more informative or enlightening name?
Use Case Identifies What Users Want J.N.Kotuba SYST Object Oriented Methodologies 41 Write a narrative description Sequence of events or steps user goes through. Focus on mainline Straight-line sequence Then consider exceptions, options errors
Use Cases J.N.Kotuba SYST Object Oriented Methodologies 42 Analysts define use cases at three levels Brief Intermediate Fully developed
Use Case Narrative: Fill Prescription J.N.Kotuba SYST Object Oriented Methodologies 43 Step 1.Pharmacist inputs Patient ID Step 2.System displays patient medical record Step 3.Pharmacist verifies dosage, potential allergic reactions and/or interaction with other medications. Step 4.The Pharmacist fills the prescription and updates the patient’s medical record on the system with details of the new prescription. Step 5. The system prints a label which is sent to the nurses station and the Billing Dept. is given Patient and Prescription details. Alt Step 3. If the pharmacist determines a possible negative condition exists, then the Doctor is contacted Alt Step 4. The prescription is held for disposition and the process terminates with the pharmacist proceeding to the next prescription in the queue.
J.N.Kotuba SYST Object Oriented Methodologies 44 Brief Description of Create New Order Use Case
J.N.Kotuba SYST Object Oriented Methodologies 45 Intermediate Description of Telephone Order Scenario for Create New Order Use Case
J.N.Kotuba SYST Object Oriented Methodologies 46 Fully Developed Description of Telephone Order Scenario for Create New Order Use Case
J.N.Kotuba SYST Object Oriented Methodologies 48 Package: Pharmacy System Use Case Name: Review Prescription Primary Actor:Pharmacy Technician Other Participating Actors: Summary Description: When prescriptions are received at the Mercy Hospital Pharmacy, they are directed to the Pharmacy Technician. He reviews the prescription and then decides, based on the type of medication, which of three stations to direct it to for filling. Preconditions:The prescription must be for a current patient of Mercy Hospital and issued by a licensed Medical Doctor. Trigger: Prescription is received by the pharmacy. Typical Course of events: 1.Pharmacy Technician (PT) verifies that the patient is an admitted patient. 2.PT verifies that a licensed Medical Doctor issued the prescription. 3.PT logs the prescription into the system and it is assigned a serialized ID number by the system. 4.PT checks the type of medication; if it must be formulated (made-on-site), sends it to the lab station; if it is an off-the-shelf medication, sends it to the shelving station; narcotics are sent to the secure station. 5.PT enters the shelving station ID to which it was sent into the system. Alternative Paths: If the patient is not currently admitted to the Hospital, the prescription is returned to the Doctor. If the Doctor is not listed in the Pharmacy database, the prescription is referred to the Pharmacist for disposition. Post conditions: The prescription is assigned to a filling station and logged into the system for tracking. Assumptions: Related Business Rules:Prescriptions can only be accepted from licensed Physicians for patients admitted to Mercy Hospital. Author:J.N.Kotuba Date:May 2012 Example “Review Prescription” Use Case Fully Developed
Use Case Narrative: Do’s Use complete sentences How is the use case initiated and how does it end What the initial and final actions and state of the system look like Don’ts Use abbreviations or sentence fragments J.N.Kotuba 49 SYST Object Oriented Methodologies
Components of the Use Case Diagram J.N.Kotuba SYST Object Oriented Methodologies 51 Use Case Actor System Boundary
Draw the Use Case with SA J.N.Kotuba SYST Object Oriented Methodologies 52
Your Turn… J.N.Kotuba SYST Object Oriented Methodologies 53 See SLATE – I-C-E-01 Use Case For the Dental Office Appointment System, develop; Context Diagram Event table Use Case Diagram Create a narrative for each use case (Intermediate Level)
Use Case Guidelines Names Noun + Verb SYST Object Oriented Methodologies 54 J.N.Kotuba
Use Case Guidelines Nouns SYST Object Oriented Methodologies 55 J.N.Kotuba
Use Case Guidelines Avoid using implementation system specific language when writing use case narratives SYST Object Oriented Methodologies 56 J.N.Kotuba
The Use Case Model.Summary Developing the Requirements Model: The Use Case Model J.N.Kotuba SYST Object Oriented Methodologies 57 informal Use Cases are an informal description of the system; how They do not give information about how the system does things internal Or any other details internal to the system. what the system will do They just tell us what the system will do for the users. what Concentrating on what rather than how makes them more a tool for analysis than design, but... They do give us a good starting point for both Testing the system, and Prototyping the user interface.
Recap Lesson J.N.Kotuba SYST Object Oriented Methodologies 58 Learning outcomes for today Develop the requirements model Use cases Use case diagrams Use case narratives
J.N.Kotuba SYST Object Oriented Methodologies 59 What Comes Next?