the evidence pattern

The Evidence Pattern

Simon A. Perry

INCOSE UK MBSE WG

Derby – 2016-03-03

Copyright © 2015

Overview

1. Introduction

2. A (Brief) Overview of the FAF

3. The Evidence Pattern

4. Summary

5. Questions

Copyright © 2015 2

1. Introduction

• The Evidence Pattern came out of idea suggested by Colin Wood at MBSE WG Meeting

– Transport Catapult – 2014-05-12

• Developed by Simon Perry & Scarecrow

• Presented below as a set of FAF Views

Copyright © 2015 3

2. A (Brief) Overview of the FAF

• The FAF (Framework for Architectural Frameworks) was developed to improve the definition of Architectural Frameworks (AFs) – Also used to define Patterns

• The FAF is designed to force anyone defining an AF or Pattern to consider the following six questions: – What is the purpose of the AF/Pattern? – What domain concepts must the AF/Pattern support? – What viewpoints are required? – What is the purpose of each viewpoint? – What is the definition of each viewpoint in terms of the

identified domain concepts? – What rules constrain the use of the AF/Pattern?

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The Framework for Architectural Frameworks (FAF) • The FAF addresses the six questions through an MBSE

approach based around the ideas of ontology, viewpoints and framework

• Ontology – Define concepts and relationships between them

• Viewpoints and Framework – Define viewpoints organised into a framework – Viewpoints can only use concepts from the ontology

• FAF consists of: – An ontology – Six viewpoints – Supporting processes

• The FAF is defined using the FAF

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The FAF Ontology

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«ontology element»

Viewpoint Element


Architectural Framework



Concern


Architecture


Ontology


Ontology Element


Perspectiv e


Standard


View


View Element


Viewpoint


Viewpoint Concern


Rule

{via}


System

1

is related to

1..*1

1

1

rep

rese

nts

ne

ed

fo

r

1..*

1..*

1

1

co

mp

lies w

ith

0..*

1

is related to

0..*

1..*

1

1..*

1

1..*

is derived from

1..*

1..*

visualises

1

1

pro

vid

es p

rove

na

nce

fo

r

1..*

1

is related to

1..*

1..*

1

1

is related to

1..*

1..*

1

1..*

de

scrib

es

1..*

1..*

uses elements from

1

1..*

represents need for

1

1

collects together

1..*

1

describes structure of

1

1..*

constrains

1

1..*

conforms to

1

1..*

corresponds to

1

1collects together

1..*


Viewpoint Element





Concern


Architecture


Ontology


Ontology Element


Perspectiv e


Standard


View


View Element


Viewpoint


Viewpoint Concern


Rule

{via}


System

1

is related to

1..*1

1

1

rep

rese

nts

ne

ed

fo

r

1..*

1..*

1

1

co

mp

lies w

ith

0..*

1

is related to

0..*

1..*

1

1..*

1

1..*

is derived from

1..*

1..*

visualises

1

1

pro

vid

es p

rove

na

nce

fo

r

1..*

1

is related to

1..*

1..*

1

1

is related to

1..*

1..*

1

1..*

de

scrib

es

1..*

1..*

uses elements from

1

1..*

represents need for

1

1

collects together

1..*

1

describes structure of

1

1..*

constrains

1

1..*

conforms to

1

1..*

corresponds to

1

1collects together

1..*

The FAF Viewpoints – Ontology Areas

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ODV

VRV

RDV

The FAF Viewpoints • AF Context Viewpoint (AFCV)

– What is the purpose of the AF? • Defines the context for the AF • Represents the AF concerns in context, establishing why the AF is

needed

• Ontology Definition Viewpoint (ODV) – What domain concepts must the AF support?

• Defines the ontology for the AF • Derived from the AF Context Viewpoint & and defines concepts that

can appear on a Viewpoint

• Viewpoint Relationships Viewpoint (VRV) – What viewpoints are required?

• Shows the relationships between the Viewpoints that make up an AF • Groups them into perspectives. It is derived from the Ontology

Definition Viewpoint

Copyright © 2016 8

The FAF Viewpoints continued • Viewpoint Context Viewpoint (VCV)

– What is the purpose of each viewpoint? • Defines the context for a particular Viewpoint • Represents the Viewpoint concerns in context for a particular

Viewpoint, establishing why the Viewpoint is needed. It is derived from the AF Context Viewpoint

• Viewpoint Definition Viewpoint (VDV) – What is the definition of each viewpoint in terms of the

identified domain concepts? • Defines a particular Viewpoint • Shows the Viewpoint Elements (and hence the Ontology Elements)

that appear on the Viewpoint

• Rules Definition Viewpoint (RDV) – What rules constrain the use of the AF?

• Defines the various rules that constrain the AF

Copyright © 2016 9

The FAF Viewpoints

Copyright © 2016 10

«perspective»

Architectural Perspectiv e

«viewpoint»

AF Context Viewpoint

«viewpoint»

Ontology Definition Viewpoint

«viewpoint»

Viewpoint Relationships Viewpoint

«viewpoint»

Rules Definition Viewpoint

«viewpoint»

Viewpoint Context Viewpoint

«viewpoint»

Viewpoint Definition Viewpoint

{The Rules Definition Viewpoint is

related to ALL the other Viewpoints

and defines the Rules that constrain

the Architectural Framework.

Relationships to other Viewpoints are

omitted from this diagram for clarity.}

1

is derived from

1

1

defines relationships between viewpoints defined in

1

1..*

is derived from

1

1..*

defines viewpoints using

elements from

1

1

defines viewpoint to meet needs from

1

1

is derived from

1

3. The Evidence Pattern

• Will be presented using FAF Views – AFCV

– ODV

– VRV

– RDV

– VCV, VDV & example for each of the Pattern’s four Viewpoints: • Claim Definition Viewpoint

• Argument Viewpoint

• Evidence Viewpoint

• Counter-Claim Viewpoint


AFCV [Package] Pattern Aims [Architectural Framework Context View showing Ev idence Pattern aims]

«concern»

Support definition of ev idence-

based claims

«concern»

Allow claims to be

made

«concern»

Allow supporting

arguments to be

established

«concern»

Allow reinforcing

ev idence to be

established

«concern»

Ensure linking

relationships are

established

«concern»

Must allow counter-

claims to be made

Evidence Pattern Context

Claimant

Refuter

«include»

«include»

«include»

«constrain»

«include»

3.1 AFCV showing Evidence Pattern aims

ODV [Package] Concepts [Ontology Definition View showing Ev idence Pattern concepts]


Claim-Argument Link


Argument


Argument-Ev idence Link


Claim


Claimable Item

{abstract}


Claimant


Counter-Claim


Ev idence


Subject

0..*

counters

0..*

0..*

supports

0..*

1

makes 1..*

1..*supports1..* 1..*reinforces1..*

1..*is made about

1

3.2 ODV showing Evidence Pattern concepts

VRV [Package] Ov erv iew [Viewpoint Relationship View showing Ev idence Pattern Viewpoints]

«viewpoint»

Ev idence Viewpoint

«viewpoint»

Argument Viewpoint

«viewpoint»

Claim Definition

Viewpoint

«viewpoint»

Counter-Claim Viewpoint

0..*

counters items on

0..*

0..*

counters items on

0..*

1..*

shows the evidence that

reinforces arguments on

1..*

0..*

counters items on

0..*

1..*

shows the arguments that support claims on

1

3.3 VRV showing Evidence Pattern Viewpoints

Evidence Pattern Viewpoints

• Claim Definition Viewpoint – Used to define Claims for a particular Subject and to

show who made the Claims

• Argument Viewpoint – Used to show the Arguments that support a Claim

• Evidence Viewpoint – Used to show the Evidence that reinforces Arguments

• Counter-Claim Viewpoint – Used to make Counter-Claims (or supporting Claims)

about Claimable Items


RDV [Package] Rules [Rules Definition View showing Ev idence Pattern Rules]

«rule»

Rule EP04

notes

Every Claim must be made about an

identified Subject.

«rule»

Rule EP01

notes

Every Claim must be supported by at

least one Argument.

«rule»

Rule EP02

notes

Every Argument must be reinforced

by at least one Evidence.

«rule»

Rule EP03

notes

Every Claim must be made by a

defined Claimant.

«rule»

Rule EP05

notes

As a minimum one Claim Definition

View, one Argument View and one

Evidence View must be produced.

«rule»

Rule EP06

notes

A Counter-Claim View must have

EITHER one Claim OR one Counter-

Claim and at least one Claimable

Item (Claim, Counter-Claim,

Argument, Claim-Argument Link,

Evidence or Argument-Evidence

Link) that the Claim or Counter-

Claim supports or counters.«rule»

Rule EP07

notes

The Claimable Items that appear on a

Counter-Claim View must appear on

another relevant View. E.g. an

Argument that appears on a Counter-

Claim View must also appear on an

Argument View etc.

3.4 RDV showing Evidence Pattern Rules

VCV [Package] Claim Definition Viewpoint (CDVp) [Viewpoint Context View showing Clai...

«concern»

Allow claims to be

made

Claimant

«concern»

Support definition of

ev idence-based claims

«concern»

Ensure linking

relationships are

established

Claim Definition Viewpoint Context

«include»«include»

3.5 VCV showing Claim Definition Viewpoint aims

VDV [Package] Description [Viewpoint Definition View showing the Ontology Elements that app...

«viewpoint»

Claim Definition Viewpoint


Claim


Claimant


Subject

1..*

11

1..*

is made about

11

makes

1..*

VDV showing the Ontology Elements that appear on the Claim Definition Viewpoint

bdd [package] Example [CDV - Definition of Claims by Safety Officer about System safety]

«claimant»

Safety Oficer

«claim»

System is safe to

use

«subject»

System safety

«claim»

Safety requirments

have been

exceeded

«claims»

«relates to»«claims»

«relates to»

Example CDV - Definition of Claims by Safety Officer about System safety

VCV [Package] Argument Viewpoint (AVp) [Viewpoint Context View showing Argument Vi...

«concern»



«concern»

Allow supporting

arguments to be

established

Claimant

«concern»

Ensure linking

relationships are

established

Argument Viewpoint Context

«include»

«include»

3.6 VCV showing Argument Viewpoint aims

VDV [Package] Description [Viewpoint Definition View showing the Ontology Elements that appear...

«viewpoint»

Argument Viewpoint


Argument


Claim


Claim-Argument Link

1

1..*supports

1..*

1..*

1..*

VDV showing the Ontology Elements that appear on the Argument Viewpoint

bdd [package] Example [AV - Example showing Arguments supporting "S...

«claim»

System is safe to

use

«argument»

System has been

tested

«argument»

Safety statistics

are good

«supports»

«supports»

Example AV - Arguments supporting "System is safe to use" Claim

VCV [Package] Ev idence Viewpoint (EVp) [Viewpoint Context View showing Ev idence Viewp...

«concern»

Ensure linking

relationships are

established

«concern»

Allow reinforcing

ev idence to be

establishedClaimant

«concern»



Evidence Viewpoint Context

«include»

«include»

3.7 VCV showing Evidence Viewpoint aims

VDV [Package] Description [Viewpoint Definition View showing the Ontology Elements that...

«viewpoint»

Ev idence Viewpoint


Argument


Ev idence



1..*

1..* reinforces 1..*

1..*

1..*

VDV showing the Ontology Elements that appear on the Evidence Viewpoint

bdd [package] Example [EV - Example showing Ev idence reinfor...

«evidence»

Simulation results

«evidence»

Safety case results

«argument»

System has been

tested

«argument»

Safety statistics

are good

«evidence»

Analysis of safteyy

statistics

«reinforces»

«reinforces»

«reinforces»

Example EV - Evidence reinforcing the Arguments 'System has been tested' and 'Safety statistics are good'

VCV [Package] Counter-Claim Viewpoint (CCVp) [Viewpoint Context View showing Counter-Claim Viewp...

«concern»

Ensure linking

relationships are

established

Claimant

«concern»

Must allow counter-

claims to be made

Refuter

«concern»



Counter-Claim Viewpoint Context

«constrain»

«include»

3.8 VCV showing Counter-Claim Viewpoint aims

VDV [Package] Description [Viewpoint Definition View showing the Ontology Elements that ...

«viewpoint»

Counter-Claim Viewpoint


Claimable Item

{abstract}


Claim


Counter-Claim


Argument


Ev idence




Claim-Argument Link

0..*

supports

0..*

1..*

0..*

counters

0..*

VDV showing the Ontology Elements that appear on Counter-Claim Viewpoint

Example CCV - Counter-Claim made against an Argument-Evidence Link

bdd [Package] Example [CCV - Example showing Counter-Claim made against an Argument-Ev idence Link]

«evidence»

Simulation results

«argument»

System has been

tested

«counter-claim»

Simulation doesn't cov er all

cases.

«evidence»

Safety case results

«counters»

«claimant,refuter»

Simulation Specialist

«reinforces»

«claims»

«reinforces»

4. Summary

• The Evidence Pattern defines four Viewpoints for the definition of Evidence-Argument-Claim chains: – Claim Definition Viewpoint allows Claims to be defined for

a particular Subject to show who made the Claims

– Argument Viewpoint allows the Arguments that support a Claim to be identified

– Evidence Viewpoint allows any supporting Evidence that reinforces Arguments to be identified.

– Counter-Claim Viewpoint allows Counter-Claims (or supporting Claims) to be made about any type of Claimable Item


5. Questions


the evidence pattern

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