Development and Use of
Architectures in System Engineering
Motivated by
“System and Software Engineering:
Architecture Models Reconciliation”
Rosalind Lewis
USC-CSSE Workshop
October 2007
© 2007 The Aerospace Corporation
Issues Raised by
Systems & Software Architecture
Reconciliation*
•
Development budget spent on software and software-related
activities
–
–
•
•
functional richness and adaptability expected in modern products is
practically achievable (with current technology) only through large
software developments
structure of these systems is increasingly multilayer rather than
hierarchical
Systems engineering and system architecture descriptions are
often not well suited to support complex software developments
Integration problem within the context of the systems engineering
process
–
–
among design representations, specifically architecture
representations
examines reconciliation methods specific to systems and software
architecture
*Mark W. Maier, Systems Engineering, Vol. 9, No. 2, 2006 © 2006 Wiley Periodicals, Inc.
2
Composition VS Layered Hierarchies*
*Mark W. Maier, Systems Engineering, Vol. 9, No. 2, 2006 © 2006 Wiley Periodicals, Inc.
3
Formal Definitions from the
Community
“Architecture,” either of a system or of a piece of software, is taken to
mean its fundamental organization or structure. Architecture reflects basic
decisions about what a thing (system or piece of software) will consist of.
- Mark W. Maier, Systems Engineering, Vol. 9, No. 2, 2006 © 2006 Wiley Periodicals, Inc.
4
Some Architecting Scenarios
5
Determining User Needs
Air Force
CONOPS
STAR
JCD
ICD
CDD
CPD
Functional
Concepts
Enabling
Concepts
MSFD Scenario
Government
Users / Operators
Architecture
AoA
Ops Views
TEMP
Verification
Plan
Test
Plan
Sys & Tech
Views
TRD
Interface
Docs
System
Spec
Government
Acquisition
SPG
Seg X Spec
Seg Y Spec
Seg Z Spec
Seg X-1 Spec
Seg Y-1 Spec
Seg Z-1 Spec
CONOPS
Operational
Concept
Contractor
6
Three Views of the Architecture
Operational
Technical
What should the
architecture do?
What governs the
system design?
• Concept
• Opn’l Node Connectivity
• Information Exchanges
• Activity Model
• Etc.
• Technology
• Standards
System
How will the architecture
be built?
• System Node Connectivity
• System Info Exchanges
• System interfaces
• Etc.
System
Specifications
7
Translating from Operational (Capability)
to System Requirements
System
Analysis &
Control
(Balance)
Operational
Requirements
Functional Requirements
Analysis
Function 2
Function 1
Requirements
Analysis
Function 3
Function 4
Functional
Requirements Loop
Function 5
Notional Architecture(s)
U/L
Functional Analysis /
Allocation
D/L
Scheduled
Tx
Unprocessed
Data
Processed
Data
User Data & Prioritization
Mission
Data
Design Loop
Performance Requirements
Analysis
Verification
Synthesis
MoE 3
MoE 2
= funct (MOP 4)
MOP 2
= funct (MOP 1)
MoE 1
MOP 4
= funct (MOP 2,MOP 3)
MOP 1
8
MOP 3
Measures of Effectiveness
Measures of Performance
4.4 Architectural Design Process
Source: INCOSE SE Handbook
9
Synthesis
Functional-to-Physical Mapping
Synthesis transforms the functional architecture into a physical
architecture by defining the physical components needed to perform
the functions identified in Functional Analysis.
–
–
Each part of the
physical architecture
must meet at least
one functional
requirement, and any
part may support
many functions.
The physical
architecture is the
basic structure for
generating the
specifications and
baselines.
PHYSICAL ARCHITECTURE
System
SubSystem 1
SubSystem 2
SubSystem 3
x
x
x
x
SubSystem 4
SubSystem 5
Functions
Function 1
FUNCTIONAL ARCHITECTURE
•
Function 2
Sub-function 2-1
Sub-function 2-2
x
x
Sub-function 2-3
Sub-function 2-4
x
x
Sub-function 2-5
Function 3
Sub-function 3-1
x
x
Sub-function 3-2
Function 4
Sub-function 4-1
Sub-function 4-2
x
10
Example: Household Lighting –
Functional Decomposition
Control Room
Illumination
Provide
Power Source
Provide
User Control
Provide
On/Off
Control
Household
Power Lines
Simple
Switch
Contain
Controls
Provide
Variable
Control
Illuminate
Shade
Light
Source
Receive
Power
Provide
Light
Source
Dimmer
Switch
Switch
Housing &
Faceplate
Orient
Light
Source
Lamp
11
Space Communications Architecture
•
Communications architecture consists of many individual communications
links.
Relay
Satellite
Sensor
Satellite
Mission
Data
Satellite
In Orbit
TT&C
Uplink
Launch
Phase
Return
Link
Crosslinks or
Intersatellite Links
Forward
Link
TT&C
Downlink
Return Link
Forward Link
Mission
Data
Return
Link
Relay
Satellite
Relay
Satellite
TT&C
Forward
Link
Intersatellite
Links
Uplink
Downlink
Uplink
Downlink
TT&C
Ground Stations
12
Sensor
Satellite
Elements of Systems
Effectiveness
(a space communication example)
•
Constellation Availability
–
•
Connectivity
–
•
Percentage of time that the constellation is fully functional
How data flows from space to the user
Robustness
–
Ability to deal with failures and threats and continue to be effective
13
Practical Problem of Selecting
Most Cost-Effective Alternative
Effectiveness
ALT 4
Threshold
Effectiveness
ALT 3
ALT 1
ALT 2
Cost
Cost
Decision-maker considers:
- Cost *
- Effectiveness*
- Politics
- Force structure
- Schedule
- Risk*
- Flexibility (scenarios)*
- Budget (affordability)
- ...
*Covered in AoA
14
Alternatives Description and
Concepts of Operation (CONOPs)
•
A Concept of Operations (CONOPs) should be developed for
each design alternative
•
•
•
•
•
•
Describe the operation and maintenance of the system and how it
will be deployed during operations
Identify staffing levels to operate and support the system
Discuss how the system will be operated and maintained and its
interactions with other operating systems
Identify how the system fits into the existing (e.g. command and
control) system and identify any unique requirements
Describe the basing mode and any special requirements for
basing, support, etc.
Additional description may include:
–
–
Functional decomposition per system per alternative
Functional flow and typical timeline of alternatives
15
Architecting and Engineering
Functions
Architecting
Architecture
Definition
Very
Broad
Needs
Concept
Exploration
Performance
Requirements
Engineering
Design and
Development
Subsystem
Requirements
16
Production & Deployment
Req’t
Generation
Users &
Operators
Architecting &
Engineering
Usage of the INCOSE logo does not imply any endorsement
of the contents of this presentation.
All trademarks, service marks, and trade names are the
property of their respective owners.
17