System Engineering

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System Engineering
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Overview

• Before software can be engineered, the system it
  is part of must be understood. The overall
  objective of the system must be determined, the
  role of the system elements (hardware, software,
  people, data, etc.) must be identified, and the
  operational requirements must be created.

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Systems

• Don't take a "software-centric" view of the
  system consider all system elements before
  focusing on software.
• Good system engineering begins with a clear
  understanding of the "world view" and
  progressively narrows until technical detail is
  understood.
• Complex systems are actually a hierarchy of
  macro-elements that are themselves systems.

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Example

• Denver International Airport
• A baggage handling system using a system of
  conveyors and carts which would deliver
  individual bags to specified destinations.

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Systems?

• over 17 miles of track
• 5.5 miles of conveyors
• 4000 carts
• 2700 photo cells
• 59 bar code readers
• 311 radio frequency readers
• more than 150 computers

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Computer-Based System

• Software
• Hardware
• People (Users/Operators)
• Database
• Documentation
• Procedures (Workflow)

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System Modeling

• Define the processes that serve the needs of the
  view under consideration.
• Represent the process behavior and the
  assumptions on which the behavior is modeled.
• Explicitly define the exogenous (links between
  constituents) and endogenous (links between
  constituent components) input to the model.
• Represent all linkages (including outputs)
  required to understand the view.

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Product Engineering

• Requirements engineering (world view)
• Component engineering (domain view)
• Analysis and Design modeling (element view -
  software engineers)
• Construction and Integration (detailed view -
  software engineers)  

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• Requirements elicitation
• find out from customers what the product
  objectives are, what is to be done, how the
  product fits into business needs, and how the
  product is used on a day to day basis

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• Requirements analysis and negotiation
• requirements are categorized and organized
  into subsets, relations among requirements
  identified, requirements reviewed for
  correctness, requirements prioritized based on
  customer needs

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• Requirements specification
• work product produced describing the function,
  performance, and development constraints for a
  computer-based system

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• System modeling
• system representation that shows relationships
  among the system components

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• Requirements validation
• examines the specification to ensure requirement
  quality and that work products conform to agreed
  upon standards

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• Requirements management
• set of activities that help project team to
  identify, control, and track requirements and
  changes as project proceeds