Business information systems analysis

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Business information systems analysis

  1. 1. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd SYST 430: BIS Analysis & Development Business Information Systems Analysis Abou-Bakr Zayd aboubakr@K4B.net Spring 2003
  2. 2. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd BIS & e-commerce Quality Life-Cycle QualityLife-Cycle
  3. 3. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:Data&ProcessModeling Data Flow Diagrams (DFD): • DFD shows how data moves through an IS (what the system does) but doesn’t show program logic or processing steps (how it does it) • That distinction is important because focusing on implementation issues at this point would restrict the search for the most effective system design
  4. 4. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:Data&ProcessModeling Data Flow Diagrams (DFD): Symbols Gane & Sarson Symbols Symbol Name Yourdon Symbols Process Bank Deposit Bank Deposit Students Students Apply Payment Apply Payment Customer Customer Data Flow Data Store External Entity
  5. 5. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:RequirementsModeling Data Flow Diagrams (DFD): Process Symbol • A Process receives I/P data & produces O/P data that has a different content • Processes are black boxes that contain the business logic/rules that transforms the data & produce required results Calculate Gross Pay Hours Worked Pay Rate Gross Pay Calculate Gross Pay Hours Worked Pay Rate Black Hole
  6. 6. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:RequirementsModeling Data Flow Diagrams (DFD): Data Flow Symbol • A Data Flow is a path for data to move from one part of the IS to another • A Data Flow in a DFD represent one or more data items; the diagram doesn’t show its structure & detailed contents Grade Student Work Submitted Work Graded Work Date of Birth Final GradeGrade Student Work Student Grade Gray Hole
  7. 7. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:RequirementsModeling Data Flow Diagrams (DFD): Data Store Symbol • A Data Store is used to retain data because processes need to use the stored data at a later time • DFD doesn’t show the detailed contents of a data store; the specific structure & data elements are defined in data dictionary Create Invoice Post Payment Accounts Receivable Invoice Invoice Detail Payment Detail Courses Students Post Payment Book Flight Payments Passengers Class List Customer Payment Flight Request
  8. 8. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:RequirementsModeling Data Flow Diagrams (DFD): External Entity Symbol • An External Entity is a person, department, outside organization, or other IS that provides data or receives O/P • External Entities show the boundaries of the IS and how it interacts with the outside world Verify Order Invoice Customer Bank Accounts Payments Order Customer Payroll Department Employee Paycheck Payment Bank Deposit
  9. 9. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:Data&ProcessModeling Data Flow Diagrams (DFD): Context Diagrams • Based on fact-finding results gathered during requirements modeling (through different fact finding techniques), information about how various people, departments, data, and processes fit together to support business operations can now be represented graphically • Context Diagram: is a top level view of an IS that shows system boundaries & scope • To draw a context diagram, a single process symbol (process 0) that represents the entire IS is placed in the center of the page and all external entities are placed around the perimeter of the page then data flows are used to connect the entities to the central process
  10. 10. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:RequirementsModeling Data Flow Diagrams (DFD): Context Diagram Grading System Students Records System Student Instructor 0 Graded Work Class Roster Submitted Work Final Grade Grade Report Grading Parameters
  11. 11. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:RequirementsModeling Data Flow Diagrams (DFD): Diagram 0 Assign Final Grade Students Records System Student Instructor 2 Graded Work Class Roster Submitted Work Final Grade Grade Report Grading Parameters Establish Grade Book Grade Student Work Produce Grade Report Grade Book 1 3 Grading Detail Class Detail Grade Book Student Grade 4
  12. 12. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:Data&ProcessModeling Data Flow Diagrams (DFD): Strategies & Rules • There are different strategies for developing a set of DFDs: – Top-Down – Bottom-Up • Conventions for DFDs: – Each context diagram must fit in one page – The process name in the context diagram should be the name of the IS – Use unique names within each set of symbols – Do not cross lines – Use a unique reference number for each process symbol • Balancing: preserving the I/P & O/P data flows of the parent on the child DFD
  13. 13. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:Data&ProcessModeling Data Dictionary: Overview • A set of DFDs produces a logical model of the system but the details within those DFDs are documented separately in a Data Dictionary • A Data Dictionary or Data Repository is a central storehouse of information about the system’s data, where analysts collect, document & organize specific facts about the system including the contents of data flows, data stores, external entities & processes • Data Dictionary defines & describes all data elements & meaningful combinations of data elements • Data Element (item or field) is the smallest piece of data that has meaning within an IS (e.g. student grade, salary, social security number, account balance, company name) • Data Elements are combined into records or data structures, where a Record is a meaningful combination of related data elements that is included in a data flow or data store
  14. 14. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:Data&ProcessModeling Data Dictionary: Documenting Data Elements • Data Element Name / Label • Alternate Names • Type & length • O/P format • Default value • Prompt, Column header, or Field Caption • Source • Security • Responsible user(s) • Acceptable values & data validation • Derivation formula • Description / Comments
  15. 15. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:Data&ProcessModeling Data Dictionary: Documenting Data Flows • Data flow Name / Label • Alternate Names • Description • Origin / Source • Destination • Record • Volume & frequency
  16. 16. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:Data&ProcessModeling Data Dictionary: Documenting Data Stores • Data Store Name / Label • Alternate Names • Description • I/P Data flows • O/P Data flows • Record • Volume & frequency
  17. 17. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:Data&ProcessModeling Data Dictionary: Documenting Processes • Process Name / Label • Purpose / Description • Process Number • I/P Data flows • O/P Data flows • Process Description
  18. 18. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:Data&ProcessModeling Data Dictionary: Documenting External Entities • External Entity Name • Alternate Names • Description • I/P Data flows • O/P Data flows
  19. 19. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:Data&ProcessModeling Data Dictionary: Documenting Records • Records or Data Structure Name • Alternate Names • Definition / Description • Record content or composition
  20. 20. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:ObjectModeling Object Oriented Concepts: Overview • Object Oriented analysis describes IS by identifying things called objects that can represent a real person, place, event or transaction (e.g. patient makes appointment with a doctor: all 3 are objects) • The Object Oriented analysis is a new approach that sees a system from the viewpoint of the objects themselves as they function & interact with system • The end product of Object Oriented analysis is an Object Model, which represents the IS in terms of Objects & Object Oriented concepts • The main benefit of Object Oriented approach is using objects and program code modules that can be reused • Structured Analysis modeling using DFDs treated data & processes separately, while in Object Oriented analysis, Objects include data & the processes that affect that data; Attributes that characterize the object & Methods that the object performs when it receives a message
  21. 21. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:ObjectModeling Object Oriented Concepts: Objects STUDENT STUDENT Object Attributes Methods Student Number Name Telephone Date of Birth Fitness Record Status Add fitness class Drop fitness class Change telephone Change status Update fitness record Instances of the STUDENT Object 970075 Soha Sayed 0105005000 10-10-80 X Current Characteristics that describe the STUDENT Object Tasks that the STUDENT Object can perform Encapsulation means that all data & methods are self contained making the object appear as a black box
  22. 22. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:ObjectModeling Object Oriented Concepts: Objects INSTRUCTOR INSTRUCTOR Object Attributes Methods Instances of the INSTRUCTOR Object 101 Zaki Morad 0101001000 Aerobics Part Time Current Characteristics that describe the INSTRUCTOR Object Tasks that the INSTRUCTOR Object can perform Instructor Number Name Telephone Fitness Class taught availability Status Teach fitness class Change telephone Change availability Change status
  23. 23. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:ObjectModeling Object Oriented Concepts: Objects FITNESS CLASS SCHEDULE Fitness Class Schedule Object Attributes Methods Fitness Class Number Date Time Type Location Instructor Number Max Enrollment Add fitness class Delete fitness class Change date Change time Change Instructor Change Location Change Enrollment REGISTRATION RECORD Registration Record Object Attributes Student Number Fitness Class Number Registration Date Fee Status Methods Add Student Drop Student Notify Instructor of add Notify Instructor of drop Notify all of fitness-class cancellations
  24. 24. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:ObjectModeling Object Oriented Concepts: Attributes STUDENT Object State Future Registered but has not started to attend Current Registered attending 1 or more classes Past Attended 1 or more classes in the past Status
  25. 25. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:ObjectModeling Object Oriented Concepts: Methods Method: Steps Add Student 1. Add new student instance 2. Record student number 3. Record student name 4. Record student telephone number 5. Record student date of birth 6. Record sex of student 7. Record state of student 8. Save new student data
  26. 26. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:ObjectModeling Object Oriented Concepts: Messages STUDENT Attributes Methods Student Number Name Telephone Date of Birth Fitness Record Status Add student Delete student Add fitness class Drop fitness class Change telephone Change status Update fitness record Message: ADD tells the STUDENT class to perform all the steps needed to add a STUDENT instance Message: DELETE tells the STUDENT class to perform all the steps needed to delete a STUDENT instance Polymorphism is the concept when a message gives different meanings to different objects
  27. 27. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:ObjectModeling Object Oriented Concepts: Classes VEHICULE Attributes Methods Make Model Year Weight color Start Stop park Attributes Car Attributes Load Limit Truck Attributes Emergency Exit Location School Bus Uncommon Attributes Uncommon Attributes Common Attributes Common Methods
  28. 28. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:ObjectModeling Relationship among Objects & Classes: Dependency School Bus Attributes Methods Bus Number Route Number Start Time Finish Time Driver Pick Up Drop Off Bus Route Attributes Route Number Stop Number Stop Location Stop Time Passengers Methods Add Stop Delete Stop Change Time Dependency Follows
  29. 29. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:ObjectModeling Relationship among Objects & Classes: Association Student Attributes Methods Student Number Name Telephone Date of Birth Fitness Record Status Add Student Delete Student Add fitness class Drop fitness class Change telephone Change status Update fitness record Registration Record Attributes Student Number Fitness Class Number Registration Date Fee Status Methods Add Student Drop Student Notify Instructor of add Notify Instructor of drop Notify all of fitness-class cancellations Association Adds/Drops Fitness Class
  30. 30. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:ObjectModeling Relationship among Objects & Classes: Aggregation Employee Attributes Methods Name Date of Birth Social Security Number Telephone Hire Date Title Pay Rate Department Get Hired Terminate Change Department Department Attributes Department Number Department Name Budget Code Department Head Employees Methods Prepare Budget Hire Employees Develop Plans Aggregation Belongs To
  31. 31. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:ObjectModeling Relationship among Objects & Classes: Inheritance Employee Attributes Methods Social Security Number Telephone Hire Date Title Pay Rate Get Hired Get Fired Change Telephone Instructor Attributes Type of instructor Social Security Number Telephone Hire Date Title Pay Rate Methods Get Hired Get Fired Change Telephone Inheritance
  32. 32. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd UML: Use Case ModelingANALYSIS:ObjectModeling Produce Fitness Class Roster Student Add Fitness Class <<uses>> Instructor Change Availability <<uses>> Update Instructor Information Use Case Modeling Examples
  33. 33. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:ObjectModeling UML: Use Case Modeling Add New StudentAdd New Student Use Case Name: Successful Completion: 1. Managers Checks Fitness-Class Schedule object for availability 2. Managers notifies student 3. Fitness-Class is open and student pays fee 4. Manager registers student Alternative: 1. Managers Checks Fitness-Class Schedule object for availability 2. Fitness-Class is full 3. Managers notifies student Add New Student Actor: Student/Manager Description: Describes the process used to add a student to a fitness class Precondition: Student requests fitness class Postcondition: Describes the process used to add a student to a fitness class Assumptions: None Use Case Description to document the process
  34. 34. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:Data&ProcessModeling UML: Use Case Diagrams Student Instructor Manager Add Fitness Class Add Instructor Change Schedule Adds Notifies Notifies NotifiesNotifies Notifies Get Assigned Check and update Use Case Diagram a visual summary of several related use cases within a system or subsystem
  35. 35. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:Data&ProcessModeling UML: Class Diagrams Sales Manager Attributes Methods Sales Rep Attributes Methods Sales Office Attributes Methods Customer Attributes Methods Order Attributes Methods Items Ordered Attributes Methods 1 1 1 1 1 1..*0..* 0..* 0..* 0..* 0..* 1 Manages Assigned to AssignedManages Places Includes Class Diagrams a detailed view of a single use case, and the relationship among the classes
  36. 36. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:Data&ProcessModeling UML: Sequence Diagrams Student Manager Fitness-Class Schedule Registration Record Request Fitness-Class Notify Pay Check Register Focus Sequence Diagrams: a dynamic model of a single use case, showing interaction among classes during a specified time period Messages
  37. 37. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:Data&ProcessModeling UML: State Transition Diagrams Future Current Past Enrolls Attends Fitness-Class Drops Fitness-Class Drops Fitness-Class Fitness-Class Canceled Inactivity for 12 months State Transition Diagram: shows how an object changes from one state to another, depending on events that affect the object
  38. 38. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:Data&ProcessModeling UML: Activity Diagrams Customer inserts ATM card Customer enters PIN Customer requests cash Customer needs cash Card is accepted PIN is accepted ATM adjusts balance ATM provides cash ATM notifies customer Sufficient funds available Sufficient funds not available Activity Diagrams: resembles a horizontal flow chart that shows the actions & events as they occur, their order and outcomes
  39. 39. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:Data&ProcessModeling Completion of Systems Analysis: • Systems Requirements Document: – contains the requirements for the new system, describes the alternatives that were considered and makes a specific recommendation to management. – This important document is the starting point for measuring the performance, accuracy & completeness of the finished system before entering the system design phase – It represents the contract that identifies what must be delivered by system developers to users • Presentation to Management – Begin with purpose & primary goals & objectives of the system – Summarize the primary viable alternatives including cost, advantages & disadvantages – Chosen alternative and explanation • Management decision: – Develop in-house system – Modify current system – Purchase / customize S/W package – Perform additional systems analysis work – Stop all further work
  40. 40. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:Data&ProcessModeling Transition to Systems Design • The transition from systems analysis to design is the transition from the logical design to the physical design of the system • Logical Design (conceptual design or essential model): defines the functions & features of the system and the relationships among its components. It includes the system’s O/P produced, I/P needed, and processes performed without regard to how tasks will be accomplished physically and methods of implementation (What? Completed in Analysis Phase) • Physical design (functional design): is a plan for the actual implementation of the system. It is built on the system’s logical design and describes the implementation of a specific set of systems components (How? Completed in Design Phase) • Logical & Physical Design are closely related as good systems design is impossible without careful & accurate systems analysis. In fact, the design phase typically cannot begin until analysis work is complete
  41. 41. BIS AnalysisCopyright © 2003 Abou-Bakr Zayd ANALYSIS:References • H. Deitel, P. Deitel & K. Steinbuhler, e-Business and e- Commerce for Managers, 2001 • G. Shelly, T. Cashman & H. Rosenblatt, Systems Analysis and Design (4th ), 2000 • J. Whitten, L. Bentley & K. Dittman, Systems Analysis and Design Methods (5th ), 2000

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