CONTEXT of Context of System(s) To Be Developed
Putcha V. Narasimham
Knowledge Enabler Systems
Context---Online Dictionary
• the set of circumstances or facts that surround a particular event, situation, etc.
http://dictionary.reference.com/browse/context?s=t
23SEP13Context of Context of STBD
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What is off context is NOT shown
Context of Systems & Processes
Context is
1. What immediately surrounds referent
2. Specific to the referent
3. A close up view of the referent and its vicinity
4. NOT what is beyond
23SEP13Context of Context of STBD
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Context
Referent
Off Context or Irrelevant
For Correct Context Specification
The referent must be well-known at least as a black-box
Its internals may NOT be known (not shown)
It can be single or
Multiple—to be checked
What immediately surround the referent must be well-known and specified
The rest are deliberately ignored
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23SEP13Context of Context of STBD
SSAD Starts with Context Diagram
• The STBD .. a black-box
• No internal details are known / shown
• External Entities--independent of STBD
• Objects or Data flow between EEs and STBD
23SEP13Context of Context of STBD
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SystemTo Be
Developed
External
Entity 1
External
Entity 2
External
Entity 3
External
Entity n
OOAD Starts with Use Case Diagram
• System to be Developed STBD Provides named SERVICES
• Through separate Use Case Dialogs
• To each Role (Actor may play many roles)
• Leading to UC GOAL
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Use-case Name 1
Use-case Name 2
Use-case Name N
STBD Name
Syst
em
bo
un
dar
y
Act
or
: R
ole
Nam
e
23SEP13Context of Context of STBD
Implied Assumptions
• STBD is just ONE
• An unverified implied assumption
• A Single STBD is often force fitted
• STBD may NOT be single
• It may consist of SEPARATE INDEPENDENT parts
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23SEP13Context of Context of STBD
1
2
5
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Force Fitting a Single STBD?
• What is assumed to be a Single STBD
• May be better modeled as
• Two or more independent &
separate Systems to be Developed
• See some examples
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23SEP13Context of Context of STBD
12
5
4
3
Chess Game System
1. It is a game management software
2. Players are independent external entities
3. If 1 were to also play chess, would the software player be a part of 1 or separate?
A. Keep 1 &3 Separate?
B. Combine 1 & 3 ?
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23SEP13Context of Context of STBD
1 Chess
Game
System 3 Software
Player
2 Human
Player
Airport Check-in Kiosk
1.Is it a separate system or a part of combination of three?
2.How are they related
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23SEP13Context of Context of STBD
A:
Check-
in Kiosk
C:
Dispatch
Control
System
B:
Reservation
System
E-Shop
1.Is it a single system or separate systems?
2.How many?
3.Which of them can be combined
4.And which should NOT be combined?
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23SEP13Context of Context of STBD
1 E-Catalog
& Shopping
Cart
3 Warehouse
2 Billing
4 Delivery
5 Returns
Relating the SYSTEMS to be developed
The SYSTEMS to be developed are named but HOW are they RELATED?
23SEP13Context of Context of STBD
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1 Chess
Game
System3 Software
Player
2 Human
Player1 Check-
in Kiosk
3 Despatch
Control System
2 Reservation
System
1 E-Catalog &
Shopping Cart
3 Warehouse
2 Billing
4 Delivery
5 Returns
What is off CONTEXT is NOT shown
C
CONTEXT
CONTEXT of Context
1.At times we need to get a BIGGER picture
2.That is the CONTEXT of context
3.And the BIGGER Picture is:
4.TO BE PROCESS MAP
5.Can be a Class Diagram also
23SEP13Context of Context of STBD
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Context
Referent
Off CONTEXT & Irrelevant
The BIGGER Picture: TWO possibilities
TO BE Process Map Class Diagram
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23SEP13Context of Context of STBD
The BIGGER Picture: TO BE Process
• Provides a common visible & verifiable reference
• Makes implied assumptions and designs explicit
• Shows coupling and dependencies of entities and flows of objects, data and information
• Provides basis to assess and explore alternatives
• Exposes potential anomalies as modeling evolves
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23SEP13Context of Context of STBD
Start with Business Deliverables
• Select Customers to be served
• Determine what they want i.e. the Business Deliverables
• Now work backward
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23SEP13Context of Context of STBD
Evolve the TO BE Business Processes
Determine & Design What should be the Internal
Business Processes and
Inputs / Supplies
Get all stakeholders to agree
Now you have a well-designed TO BE Process
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Supplier
Organization
Business
Processes
cust
om
er
23SEP13Context of Context of STBD
Real-world conditions +
Organizational policies and decisions
Shape the TO BE Process Some parts have to be
manual MP1-3 Some others can be
Automated AP1-5
TO BE Process--Manual & Automated 18
MP1
MP2
AP4
AP3
AP2
MP3
AP5
AP1
Exte
rnal in
puts
Busi
ness
Delivera
ble
s
Internal Outputs and Inputs
AutomatedManual
23SEP13Context of Context of STBD
Further Partitioning of Automated Process
Partitioning criteria
Size (not applied)
Specialization, (not applied)
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MP1
MP2
AP4
AP3
AP2
MP3
AP5
AP1
Exte
rnal in
puts
Busi
ness
Delivera
ble
s
Internal Outputs and Inputs
AutomatedManual
23SEP13Context of Context of STBD
Further Partitioning of Automated Process
Partitioning criteria
Independence / Separable AP1 & AP2
Dependence / Coupling AP3, AP4 and AP5
So there are 3 STBDs
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MP1
MP2
AP4
AP3
AP2
MP3
AP5
AP1
Exte
rnal in
puts
Busi
ness
Delivera
ble
s
Internal Outputs and Inputs
AutomatedManual
23SEP13Context of Context of STBD
Context Diagram of AP1
A Context Diagram should have only ONE STBD,
Here AP1 has only two External Entities
Supplier (not shown) & MP2
Others are NOT in AP1’s context.
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MP2AP1
Exte
rnal in
puts
23SEP13Context of Context of STBD
Context Diagram of AP2
A Context Diagram should have only ONE STBD, here AP2
AP2 has only two External Entities
MP2 and MP3
Others are NOT in AP2’s context.
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MP2 AP2
MP3
23SEP13Context of Context of STBD
Context Diagram of AP3+AP4+AP5
The Context of STBD3 contains
3 External Entities
MP1, MP3 and External Customer (not shown)
Others are NOT in STBD3’s context.
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MP1
AP4
AP3 MP3
AP5
Busi
ness
Delivera
ble
s23SEP13Context of Context of STBD
Conclusion
• Context and Use Case Diagrams also have explicit logical basis for their creation & validity
• System To Be Developed is NOT always ONE
• There are criteria to determine and justify the number of Systems to be Developed
• Their utility, size and complexity can be estimated and managed with TO BE Process Maps
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23SEP13Context of Context of STBD
Class Diagram can also be used for C of C
• Each Class has it’s own Context
23SEP13Context of Context of STBD
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A
C
H
DB
G
E
F
Context of E: B & G
Context of A : C &F
Context of D: B, F & H
Some of A--H
maybe
combined
into one Unit
Design & Review Services
• Would be glad to create and or review the To Be Processes
• And proceed to identifying STBDs systematically
• Trial docs and demo sessions are free
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START
23SEP13Context of Context of STBD