Open Specifications for Assisted Living Infrastructure

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Open Specifications for Assisted Living
Infrastructure

• Elsa L Gunter

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Need for Specifcations

• What You See Is What You Get systems are
• Fragile, buggy, hard to revise
• Reliable and flexible architectures require
• Clear and precise statements of expected /
  guaranteed system behavior, and
• Clear statements of what expectations from
  environment where system is used

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Specification Artifacts

• W World Knowledge (Domain Knowledge or
  Environment)
• R Requirements (what the end user really needs)
• S Specification (restricted form of
  requirements, stated in terms understood by both
  the end user and the developer)
• P Program (Implementation deliverable)
• M Machine (Programming Platform)
• Most developer focus on P and at most S
• We need to focus on W and R

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Specification Artifacts
Environment
System
W
R
S
P
M
Domain (World) knowledge provides presumed
facts about the environment.
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Specification Artifacts
Environment
System
W
R
S
P
M
Requirements that indicate what the customer
needs from the system, described in terms of its
effect on the environment.
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Specification Artifacts
Environment
System
W
R
S
P
M
Specification providing enough information for a
programmer to build a system that satisfies the
requirements.
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Specification Artifacts
Environment
System
W
R
S
P
M
Program implementing the specification on the
given program platform.
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Specification Artifacts
Environment
System
W
R
S
P
M
Programming platform (Machine) provides a basis
for programming a machine to satisfy the
specification.
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Designations
Environment
System
eh
ev
sv
sh
Visibility
Control
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Specification Artifacts
Environment
System
W
R
S
P
M
End-user wishes for
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Specification Artifacts
Environment
System
W
R
S
P
M
Developer must supply
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Specification Artifacts
Environment
System
W
R
S
P
M
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Specification Artifacts
Environment
System
W
R
S
P
M
End-user must guarantee
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Specification Artifacts
Environment
System
W
R
S
P
M
Common Language Refinement
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Example Patient Monitoring System
Requirement a system to warn a nurse if a
patients heart stops beating.
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Artifacts

• Domain knowledge W
• A nurse is always at the nurses station and can
  hear a bell.
• If the patients heart has stopped, then a sensor
  on the patients chest ceases detecting the sound
  of a heartbeat.
• Programming platform M
• Sound sensor.
• Bell.
• Computer that can activate the bell based on
  information from the sensor.
• Specification S
• If the sensor has not reported a signal above a
  cutoff threshold in the last two seconds, sound
  the bell.

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Role of the Specification

• Specification provides communication between user
  and developer expressed in the common vocabulary
  of environment and system.
• Enables factorization of responsibilities between
  user and developer.
• Users work with designations visible in the
  environment (viz. W and R).
• Developers work with designations visible in the
  system (viz. P and M).

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Kinds of Formal Specifications

• Basic functional (relates input sequences to
  output sequences)
• Real-times specs
• Security specs
• Resource specs (e.g. power)

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What I Need From You

• Your Requirements
• What do elderly need
• Usability
• What does the medical profession need
• Reliability
• Security (HIPPA)
• Interoperability
• Medical Social Domain Knowledge
• How do patients actually live?
• How is information recorded and reported
• Review of Specifications

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What I Give (to You?)

• Open Database of
• Domain Knowledge
• Given in English as experts expressed it
• Model in formal mathematics suitable for proofs
• Proofs of sensibility
• Requirements
• English, math, sensibility proofs
• Specifications
• English, math
• Proofs that Specification satisfies Requirements
• Allows for multiple implementations
  (interoperablility)