IMS 5024

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IMS 5024

• Event-driven modelling

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Content

• Individual assignment
• Pitfall revisited
• Group assignment
• BSD
• SAP R/3
• Place in ISD
• Evaluation of event driven modelling
• Reading list for next week

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Individual assignment

• Date due 29 August 2002
• Difference between social and technical
• Show understanding of the subject matter
• Questions e-mail Bahar directly

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Teaching Assistant

• Bahar Jamshidi
• E-mail
• bahar.jamshidi_at_infotech.monash.edu.au
• Queries about marks
• Other queries
• Thursday 6 7 PM

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My consultation times

• Monday 10 11.30 am
• Tuesday 2 3.30 pm

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Pitfalls

• Not starting early
• Reading, more reading and then some reading.
• Plagiarism !!!!!

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Different perspectives

• Process
• Data
• Behaviour / Stimulus response how system reacts
  to external and internal events
• Difference

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Techniques

• State transition diagrams
• Business rules diagram (BRD)
• Event-driven process chain methodology
• Petri nets
• Finite state machines

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Key constructs of BRD
State
Condition
Event
Signal
Blob
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Definition of a business rule

• An explicit state change context in an
  organisation which describes the states,
  conditions and signals associated with events
  that either change the state of a human activity
  system so that subsequently it will respond
  differently to external stimuli or reinforce the
  constraints which govern a human activity system

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Business rule types
Policy rules
Processing rules
Implementation rules
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Steps in creating BRD

• Identify candidate business (policy) rules
• Identify candidate events and signals
• Identify candidate objects in problem situation
• Construct object life histories (OLH) for each
  object identified
• Construct user business rule diagrams (UBRD)
• Construct business rules diagram
• Construct event specification table (EST)

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Example of candidate business rules (Policy
rules) (1)

• Orders sent by mail or telephone
• Omissions on order line leads to deletion
• Credit balance gt order value to accept order
  else reject
• Stock qty gt order qty to accept order otherwise
  reject
• One invoice for one order
• Sum of payments order value sum of credit
  notes
• One order may have many credit notes

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Example of candidate business rules (Policy
rules) (2)

• Many payments per invoice possible
• Overdue invoices occur 30 days after statement
• If product not carried reject item
• If unobtainable multiples reject item
• New order created for outstanding items
• Only good customers may obtain credit orders
• Credit balance reduced for all items on an order
  including outstanding items

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Example of candidate list of business events and
signals

• Receive customer order T
• Delete line E
• Reject order E
• Create new order E
• Send invoice M
• Generate credit note E
• Receive payment T
• Create outstanding item E
• Create new customer E
• Move to good customer E
• Move to bad customer E

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Example of a OLH
Temp cust

• Customer

Good cust
Bad cust
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Example of UBRD
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Example of BRD
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Example of EST
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SAP R/3

• Why?
• Blend business processes and technology
• Best practice processes then focus on unique
  aspects
• Blueprint used as reference model
• Business process takes center stage

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Blueprint

• Help organisations to define needs, develop
  solutions and optimize their processes
• Do not need to start from scratch
• Customisation possible
• Include functions, process, information flow and
  organisation views
• Business processes are shown in the Event-driven
  process chains

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Modelling approach

• Define / redefine the organisations goals
• Create a model to reflect the goals
• Develop unique applications
• Implement the applications

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SAP approach

• Map company processes to the blue print (reflect
  best practice)
• Define target situation
• Focus on unique aspects
• Customize and configure

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Key elements of SAP blueprint

• Events (when should something be done?)
• Tasks or functions (what should be done?)
• Organisation (who should do what?)
• Communication (What information is required to
  the right task?)

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Event-driven process chain (EPC) methodology (1)

• Event e.g.. Goods arrived
• Task / function e.g.. Verify goods
• Organisation e.g. Good receiving dept
• Information e.g. Delivery note

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Event-driven process chain (EPC) methodology (2)

• Process path
• Logical operator
• Control flow
• Information/material flow
• Resource/organisation unit assignment

Xor
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Legend

• EPC is the central view
• Event always trigger a task
• Start and end with an event
• Organisational units are added
• Navigation between process models by start and
  final event

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Example of an EPC
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Other views

• Component model describe what is done
• Organisation model Who does what and who is
  responsible
• Data model what is needed to do something
• Interaction model what information must be
  exchanged between different units

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Example of a component model
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Example of Organisation model
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Example of data model
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Example of an Interaction model
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Evaluation of Data modelling
Problem oriented Product oriented
Concep-tual Structured analysis Entity relationship modelling Logical construction of systems Modern structured analysis Object oriented analysis Structured design Object oriented design
Formal PSL/PSA JSD VDM Levels of abstraction Stepwise refinement Proof of correctness Data abstraction JSP Object oriented programming
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Advantages of Event driven modelling

• Concentrate on the problem area
• Identify business processes
• Cost

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Disadvantages of event driven modelling

• Difficult to implement
• Early days
• Cost

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Process modelling view of ISD
Objectives
Development group
Object system
Object system
Change process
Environment
Hirschheim et al see reading list
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Reading for next week

• Rumbaugh, J., Blaha, M., Premerlani, W., Eddy,
  F., Lorensen, W. (1991) Object oriented modeling
  and design. Prentice Hall, Inc. USA. Chapter
  1,2,3,4