Docstoc

8 from flow charts to UML

Document Sample
8 from flow charts to UML Powered By Docstoc
					From Flow Charts to UML - 1




       Revised by Ivor Perry Sept. 2003
                     Agenda
• Process Analysis and Modelling
• Rich Picture
• Manual Flowchart
• Data Dictionaries




                Revised by Ivor Perry Sept. 2003
       Process Analysis and Modelling
• Most approaches are structured - why?
• To answer the following questions

• Why is an information system being developed?

• How should it be developed - the process?

• How can this process be managed - the project?

• What is the best way to set down this knowledge?

• What is the best way to teach or pass on this
  knowledge?

                 Revised by Ivor Perry Sept. 2003
                  Hard and Soft Approaches
   • Soft e.g. Soft Systems Methodology (SSM) -
     Checkland
       – Emphasis on human and organisational perspective
   • Hard e.g. SSADM, DSDM
                                                                 The
       – focus on
                                                              Commonest
           • processes and transactions
           • entities about which data is stored
                                                               Approach
   • Object Orientation (OO) approach e.g. Unified
     Modelling Language (UML)
       – seeks to bring together process and data
       – an object will have attributes, but also services (e.g.
         procedures, functions)
                                                                 Coming Up
                                                                   Fast!
Curtis & Cobham Ch 16      Revised by Ivor Perry Sept. 2003
            Using Graphical Tools
• Easier for users to understand
• Demonstrate processes and business rules
  consistently
• May show business rules more clearly (ERD)
• May show process bottlenecks (Manual Flowchart)
• Assist in defining boundaries (Rich Picture, ERD)
• Useful in preventing ‘scope creep’




                 Revised by Ivor Perry Sept. 2003
          Understanding the task -the Rich Picture

                                                     enquiries
                            Permanent staff
                                                                        Customers
                                                                book

                                            Bookings                    Casual staff
                      Courses
deliver
            order

                            Rooms & courts
  Suppliers                                                                   ?
                                                                       Health & Safety
                             Revised by Ivor Perry Sept. 2003            watches
           Curtis & Cobham Ch 16
                        The Rich Picture
   • Focusses attention on the important issues
   • Helps people to visualise and discuss their roles
   • Is used to define the boundaries of the project
   • Represents 3 important elements in systems
     design
   • Elements of structure
       – boundaries, physical layout, products and services
   • Elements of process
       – what happens
   • Elements of relationships
       – the relationship between structure and process

Curtis & Cobham Ch 16   Revised by Ivor Perry Sept. 2003
                        The Data Dictionary
   • A store of data about data
   It holds
   • the name of the data element
   • the type of data it is
   • the structure, e.g. for a flow or store, the
      aggregates or data items which comprise it
   • the usage characteristics, e.g. the processes a flow
      interacts with, or the aggregates which use a data
      item.




Curtis & Cobham Ch 10     Revised by Ivor Perry Sept. 2003
                        Manual Flowcharts
   • Considers the physical processes

   • Usually used to record flow of documents in a
     manual system

   • Use commonly agreed symbols

   • NOT a system design
       – would simply lead to replicating the manual system




Curtis & Cobham Ch 10    Revised by Ivor Perry Sept. 2003
                            Manual Flowcharts
 Claim           Validate
 form             policy

            No              Yes
                                                                          Motor
Rejection          Policy         Confirmation                          Insurance
  letter            OK?              letter                               Claim
             Yes
                                    Docs in
                  Request
                                  suspense file
                 inspection


Garage              fax                                          Yes- raise
                                                                                cheque
                                                                  cheque

 Garage                              Check
 report                                                   OK?
                                     against
                                      terms                                     letter
                                                                     No -
                              Revised by Ivor Perry Sept. 2003   refuse claim
Curtis & Cobham Ch 10
               Manual Flowcharts - Summary
   Advantages
   • Easier to understand than narrative
   • Preparing a chart means the analyst has to
     understand the process
   • Incompleteness of the process is easily discovered
   • Little technical knowledge is required to
     understand a chart
   • Weaknesses in the system are shown up, e.g.
     bottlenecks, duplication of work etc.




Curtis & Cobham Ch 10   Revised by Ivor Perry Sept. 2003
               Manual Flowcharts - Summary
   Disadvantages
   • With complex systems flowcharts become
     unwieldy
   • Difficult to amend
   • Flowchart does not show informal information
     flows




Curtis & Cobham Ch 10   Revised by Ivor Perry Sept. 2003
End of Lecture




 Revised by Ivor Perry Sept. 2003

				
DOCUMENT INFO
Shared By:
Categories:
Stats:
views:16
posted:4/7/2010
language:English
pages:13