Overview of a Patternbased Reference Architecture

1
Overview of a Pattern-based Reference Architecture

• Carroll A. Hood
• GEOSS Chief Architect

2
Outline

• What is a Pattern-based Reference Architecture?
• Example
• Why is this relevant to GEOSS?

3
Pattern based Reference Architecture

• Patterns Abstractions of design solutions
• Reference Architecture (RA) Abstraction of an
  architecture with common characteristics and
  quality attributes
• Tailorable
• Reduces Risk
• Encourages Reuse
• What and Who NOT How and Why

RAs The Building Blocks for GEOSS
4
Characteristics of an RA

• Structure
• Entities
• Internal/External Interfaces
• Behaviors
• Global Rules
• Standards
• Constraints

5
Reference Architecture ExampleBuilding a Taco
6
Structure Value Stream and IPO Chart
High Level Value Stream
Go to Store
Buy Stuff
Take Stuff Home
Prepare Taco
Consume Taco
Paper
Go to Store
Pencil/Pen
Shopping List

• Check Pantry/Frig
• Make List
• Get in Car w/list
• Drive to Store

Keys
ATM Card
Input-Process-Output (IPO) Chart for one Step in
Value Stream
7
Structure Domain Collaboration Diagram
Structure provides a top-level organization,
defines entities, identifies interfaces, and
scopes the enterprise
8
Behaviors List of Use Cases

• Home
• Put Food Away (pattern)
• Into Pantry
• Into Refrigerator
• Prepare Beef
• Heat Shells
• Assemble Ingredients (pattern)
• From Pantry
• From Refrigerator
• Build Taco
• Ignore Cat (begging for people food)

• Grocery Store
• Select Commodity (pattern)
• Ground Beef
• Cheese
• Beer
• Etc.
• Manage Cart (pattern)
• Insert item
• Remove Item
• Pay for Groceries

Behaviors describe the interactions between
entities
9
Use Case Example Build Taco
Use Case ZZZ Build Taco

• Description This use case describes the
  construction of a fully-loaded taco, ready-to-eat
• Actors Me
• Preconditions All ingredients have been moved to
  the island (UC XXX Assemble Ingredients, etc)
• Flow of Events for Main Scenario
• Take heated shell from cookie sheet
• Spoon Beef inside empty shell
• Pour some taco sauce on top of beef
• Spoon dabs Sour Cream on top of that
• Sprinkle grated cheese across top
• Insert chopped tomato
• Stuff chopped lettuce on top of cheese
• Alternate Scenario
• If taco shell breaks at any point during steps
  1-7,
• place ingredients accumulated so far onto plate
  and continue with remaining step.
• put ingredients accumulated so far into new shell
  and continue with remaining steps
• Move Step 5 (cheese) to end.
• Post Conditions Ensure beer is still cold
  before moving to Dining Room
• Special Conditions none

10
Global Rules Standards and Constraints

• Standards
• To my knowledge, there are no ISO Standards that
  come into play here
• Perhaps some USDA Regulations (Food safety)
• Tastes Great, Less Filling (community-based
  standard)
• Constraints
• Budget
• Hours of Operation of Grocery Store
• Dinner Time

Constraints and standards do not define but help
shape the solution space
11
Relevance to GEOSS

• GEOSS is a system of system of systems
• No single large procurement
• Multiple entitles evolving toward GEOSS-level
  interoperability over time
• Some new elements will be developed hopefully
  with GEOSS-level interoperability in mind
• Enterprise-wide optimization will require
  collaboration between Government, Academia, and
  the Private Sector
• Reference Architectures for specific GEOSS
  elements or threads
• Provides a blueprint for development/evolution
  within a common GEOSS interoperability framework
• Allows for flexibility and innovation in design
  and implementation
• Private Sector is in best position to lead (not
  own) RA development for GEOSS
• Its what we do (This is why we are all here)
• RAs are not static they will evolve as our
  knowledge and capabilities expand
• Buy-in at a high level (i.e., RAs) will enable
  all of us to more forward at more detailed levels
  more smartly and will help GEOSS become real