Dfd of Fee Management System of University

							    Event-driven analysis
               of
Essential System Requirements
What is requirements analysis?



   Gathering, analyzing, understanding and
  documenting functional requirements of an
             information system.
Steps in …

    ing
      …

Business modeling
      ------
 Data Modeling
     -------
Process modeling
          What is ‘essential’

Set of system requirements that meets institutional
 information needs without including unnecessary
                system capabilities.
                       ------
      Requirement are conceptual in nature.
What is ‘event-driven approach’


 Based on ‘Institutional’ Events.
 System-partitioning based on responses to
 those Events.
 Early and effective involvement of subject-
 matter experts and prospective users.
 Event-driven approach supports incremental
 (iterative) development and implementation.
 Concept: Event and Response


Event is some change in an IS’s environment…
Institutional (business) event is an activity in the
users’ environment that requires a response
from the proposed IS.
Response is set of actions performed by the IS
itself whenever a certain event occurs.
Iterative System Development Process
                                               Conceptual

       Feasibility              Requirements
         Study                    Analysis
                                                            Try to avoid this
                                                               transition



    Plan Increment              Design and
                                Construction       Real data test



                     Physical

                                                     Accepted




                                                  Implemented
Iterative System Development process
       Feasibility     Requirements
         Study           Analysis




    Plan Increment      Design and    Real data test
                          Build




                                        Accepted
                     Prototyping



                                      Implemented
        Partitioning



Event partitioning scheme
Object partitioned approach
Data model
Spiral or waterfall
Prototyping
Events and Data Stores
Concept: Types of events

      External events
           ------
      Temporal events
           ------
        State events
Concept: Event and Response …
                       response
  Event


          trigger

                       IS partition



                            IS partition

Event        trigger

                               response
  Concept: Event and Response

  Student                response
  applies

            trigger
                          Register
                         application

                               Register
                              grade/mark
 Student
               trigger
sits exam
                                response
    Concept: System partitioning



For each institutional (business) event a response
   must be defined by its data inputs, its data
  processing, and its interface to stored data.
                       -----
Each response is ‘encapsulated’ in a single system
                      unit.
 Four dimensions of
System requirements


   System environment.
     System behavior.
      System data.
    System processing.
  Deliverables of the Requirement Analysis
                   Process
 General Aspects: objectives, critical success factors,
                    constraints
System Behavior Aspects: Business Events List, Event
 Scenarios, System Response Table, Context Diagram
 System Data Aspects: Entity/Relationship Diagram
  System Processing Aspects: Event Diagram, Data
     Flow Diagrams(DFD), DFD Specification
   Data/Process Interaction: CRUD matrix, Entity
                   Process View
Overview Requirements Analysis Process
Behaviour Model
Context Diagram
Description                   Process Model
Event List                    Event Diagram
System Response Table         DFD Specs
Event Scenario



              Data Model             Interaction Model
              Entities               CRUD matrix
              Relationship           Entity/Process View
              Attributes
              Normalization                        Primary path
                                                   Iterative path
System Behavior Modeling

  Users of the proposed system.
      Institutional Events.
       System Response.
        System Context.
  Institutional Event Scenario.
  Functional System Structure.
System Behavior Modeling
  Users of the proposed system
             Student
              Dean
            Examiner
       Examinations office
      University Management
            Lecturer
          Finance Office
System Behavior Modeling
          Events List Example


1. Customer places order.
2. Student Applies
3. Student pays admission fee.
4. Student passes examination,
5. Student leaves the university.
6. Examiner submits examination marks/grades.
7. Time to generate ‘marksheets’
       System Behavior Modeling
                Events List Design Tips

1. Ask the user to describe anything that occurs in their
   work that might involve the proposed system.
2. Use the language of the organization when describing
   events.
3. Make sure that the user understands that, at a high
   level, the scope of the system is being established.
4. Scenarios will be used to describe each event in more
   detail.
5. Temporal events are documented as ‘Time to ……’.
            System Behavior Modeling
                System Response List Example


Event Source Trigger      Response Name       Major output   Destination
E1    Student Application Register Application Application   …
E1    Examiner Mark/Grade Register             Mark table
….
            System Behavior Modeling
               System Response List Design Tips


For each event response, identify the source of the trigger. It should be a role
and not a specific person.
Name each trigger.
Document the major outputs that will be generated by each response.
Name the destination of each output.
Only one trigger can activate an event-response, but more terminator can be
the source of a particular trigger.
The Context Diagram will represent this table diagrammatically.
Many custodial functions (update, delete) are not identified as events and
therefore not modeled.
 System Behavior Modeling
   System Context Diagram Example

              Finance          Parents
Student


                              Lecturer
 Dean
               ARIS

                            Planning Dept
Mngmnt

               Financial
           System Behavior Modeling
            System Context Diagram Design Tips


Begin with a ‘first-cut’ model developed by the system analyst followed by
user joint sessions to complete.
Create a process representing the total system under development.
Add external database to which the system will interface (NOT the internal)
Don’t spend too much time on this diagram itself. Much more
understanding will be gained during event analysis.
Don’t iterate through this diagram too often….
Develop this diagram in parallel with event analysis.
When defining terminators, keep in mind that it is outside the system and
not part of the proposed system.
     System Behavior Modeling
     Institutional Event Scenario Example



An Examination department clerk receives…
….
….
The system should have produces the following:

- The list of all examination grades each student
- An overview of average of grades of each of the students
        System Behavior Modeling
       Institutional Event Scenario Design Tips


Describe step-by-step how the system user will interface with the
system.
Try to describe processes in a logical, conceptual way. Do not include
physical details about communication means, devices etc.
The user must be comfortable with the final scenarios.
System Data Modeling

       Data entities.
      Data attributes.
   Entity relationships.
   Normalized structure.
                 System Data Modeling
              Entity-Relationship Diagram Example

   Data Dictionary
                            Student         Course   StudyProgram
Student
ID
Surname
Date of birth             0…n         0…n
Course
Description
                          ExamGrade             Curriculum
                 System Data Modeling
          Entity-Relationship Diagram Design Tips


Identify objects in the area about which data must be stored.
Examine the events that have been identified; event often reveal data entities.
Give a textual description for each entity.
Define attributes for each entity.
Designing an E/R Diagram is an iterative process and cannot be completed in
a single step.
The E/R diagram must be completed. If not, it may not contain crucial
elements to support data access requirement for the proposed application.
The diagram must be validated as behavior and process models are build.
For details refer to the ‘Database Design’ set of slides…
Normalize…
System Processes Modeling

        Event Response.
     Process Decomposition.
  Event-Response Specification.
           System Processes Modeling
            Event-Response-Diagram Example


            StudentID
            Course
            Examdate
                                           P
            Grade
            …
                                      Check
Examiner
                                      student particulars
                                      and
                                       register Grade


                        D   Student
                                               D ExamGrade


     Event: Examiner grants examination grade
          System Processes Modeling
          Event-Response-Diagram Design Tips
      For each Event Response (row in SRT) create a DFD.
             Give the DFD the event-response name.
  Add all terminator, providing data or receiving information.
Draw data flows (arrows) between the terminator and the process.
Add data stores representing data entities for the Data Model that
           are needed and/or updated by the process.
          Draw data flows to and from the data stores.
        Specify attributes represented by the data flows.
Data/Process Interaction Modeling

          CRUD association.
         Entity Process View.
          Entity Life Cycle.
  Data/Process Interaction Modeling
                 Example CRUD Matrix.


Event-Response              Student    Exam Grade Course

Student applies               U
Student admitted              R
Examiner submits grade        R               U
Department updates course                              U
…..


 One row for each row in              One column for each
 System Response Table                    Data Entity
Data/Process Interaction Modeling
             CRUD Matrix Design Tips


     Use Event-Response-Diagrams as starting point.
An Event-Response requiring READ cannot be implemented
         without an event-Response with UDATE.
   Data/Process Interaction Modeling
                  Entity Process View Example


                                              P
 Student          Course
                                         Check
                                         student particulars
                                         and
0…n         0…n                           register Grade
ExamGrade


                             D Student
                                                  D ExamGrade

      Event: Examiner grants examination grade
Data/Process Interaction Modeling
          Entity/Process View Design Tips


Examine the data stores of an Event-Response-Diagram and
    identify corresponding entities in the Data Model.
      Draw these data stores and their relationship.
                  Show related entities.
     Data/Process Interaction Modeling
                Entity Life Cycle Diagram Example
                                 1

                                    Applicant

                   2        2                   3
                                                Admitted
                         Rejected
                                                    4
                                                        Registered
1.   Student applies
2.   Application not accepted
                                                                     5
3.   University admits student
4.   Student pays fees and selects program                       Graduated
5.   Student passes examinations
Data/Process Interaction Modeling
   Entity Life Cycle Diagram design tips
         Joint Design Workshop

Define conceptual system requirements by defining:
                  Objectives of the system.
             Scope (environment) of the system.
         All relevant Institutional (Business) Events.
   Event responses in terms of data input, data processing
         (‘business rules’), data stores, data output.

          Develop conceptual system model:
behavior diagrams, data dictionary, entity relationship diagram
Joint Design Workshop

         Participants
       Executive sponsor.
       Session chairman.
      Information Analyst.
     User representative(s).
   Subject-matter specialist(s).
   Joint Design Workshop

     Max 10 participant at one time.
Determine schedule and topics in advance.
Project Management


      Planning.
     Scheduling.
     Monitoring.
     Controlling.
      Directing.