Section 2 of book
Section 2: Dependability and Security
Introductory statement Dependability and Security can be more important
than functionality Insulin pump Ancestry.com Voter targeting MS Word Flight controller
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Systems
Author: A system is a purposeful collection of interrelated components of different kinds which work together to achieve some objective
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SocioTechnical Systems
Term since 1950s
System of more than hardware and software
Factors People Processes Laws, Regulations Organizaitons Physical Environment
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SocioTechnical SystemStack
Sociotechnical System Stack Equipment Operating System Communications and data management Application layer Business Process layer Organizational layer Social Layer
Issues in one area affect others
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Factors
Factors that affect the entire system (at creation or change) Process changes
Do you require a process change for a new s/w system? Desired change in process drives change
Job changes new roles obsolete roles
Organizational / political Important/unimportant roles
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Characteristicsof SocioTechnical Systems
Emergent properties Appear after system starts
Nondeterministic Hardware generally deterministic Software may change Other factors are hard to control
Acceptability of system will change due to various factors
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Emergent System Property
Emergent system properties Appear after systems implemented
CAD systems Multiple vendors No universal interchange format Attempts – plotting, consortium Autodesk file format
Initially, just another format After market share achieved, defacto standard
Level of sociotechnical system stack?
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Emergent System Properties
Until a sufficient population has the same technology, it is not accepted.
Collective understanding of email affects its use Etiquette (forwarding, tone) Attachments Standards of organizations
Security Storage allowances
Level of Sociotechnical Systems Stack?Chapter 10 – Socio Technical Systems9
Non Determinism
Voter tracking database
Created by incorporation of data from States Counties Data providers
Standardization of formats limited USPS, yes. Few follow the rules
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Multilevel Issues
Integration of data from diverse sources Different formats (csv, fixed cell, spreadsheet) Different intents (employee list, parent list, band
booster) Different standards of quality (employee list, band
booster, voter file) Different standards of content (fields – name,
address, phone, zip)
Human errors
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Wicked Problems
No clear solution Contradictory requirements Changing requirements Too many stakeholders
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Gradebook System
Goal: coordinate gradebook information.
Master Database of Teachers, Classes, Students, Grades
Individual database at teacher computer
Periodic grade reporting electronically Pre- internet Data card
Issues Acceptance, training, integration
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GIS System
Geograpic Information System
Datanbase of geographic features Streets Properties, Ownership, Easements Gas, Electric, Phone lines Political Boundaries (precincts, zip codes, …)
Uses Right of way procurements Maintenance – digging Public announcements
Issues: Usability of system before data set up
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