Aug. 30, 2013
SW Engineering Notes

Design - figuring out how to implement requirements
  Systems Engineering - HW vs SW implementations, esp. for Real-time systems
  SW Architecture - decide how to divide SW into subsystems and how those subsystems interact
     Many arch. patterns/styles exist
  Detailed design - subsystem details
  Look & Feel or UI Design - how user interacts with system
  DB interaction - how project interacts with database

Modeling - representing the domain or software
  Use case modeling - representing sequences of actions performed by users
    How user will do something (Click this, select that, open something)
  Structural modeling - representing classes and objects
    present in domain/SW (Unified Modeling Language (UML))
  Dynamic or behavioral modeling - representing system states and actions 
  therein
    (State space diagrams and others)

Programming - Design-->Code-->Executable
  Tools exist to turn UML (Class Diagrams and ER diagrams) into code
  Design is much more important

Quality Assurance - ensure quality objectives are met
  Review and inspection of design and code
  Testing - systematically executing SW to ensure it behaves as expected
  Examples include validation and verification

Deployment - distribution and installation
  Managing SW configurations

Management - cost estimation and planning

Maintenance

We will emphasize understanding the customer and user, OO Techniques, UML, and Agile

Agile for our purposes = iterative and adaptive development

Waterfall model -
  requirements gathering -> design -> programming -> testing -> deployment -> maintenance

  In the original model, you don't go back to the previous step

  Improved versions allow for return to the previous step, but lead to better
  models such as Agile.

  Agile models assume software engineering is a highly iterative process.
    They requirements gathering, repeat design, implementation, etc., again 
    and again.

  Example:
    Create a prototype with little functionality and rough requirements
    to help find requirements for the next iteration.

    Complete several iterations of prototypes before the stakeholders are
    satisfied.

    Complete smaller units of work more frequently.

    We find out if something doesn't work for the client much faster.

Difficulties and Risks in SW Engineering

  SW Systems have large numbers of details and complexity

    - easy to add new features
    - esp. without understanding the system
    - system might not accomodate new features

  Solution:

    Flexibility added from the start
    Division of system into subsystems
    Limited features

Uncertainty about:
  Requirements
    You can't be sure of what the client wants until deployment!
  Technology
    Can't be sure how SW will work on various platforms
    Solution: Don't use strange HW
      Don't use weird features
      Complete prototypes on planned HW

  SW Eng. Skillset
    Team members may have different skills
    Solution:  Education
      Practice/Training
      Communication about skillsets to ensure all necessary skills are
      available

  Change in project
    Solution: Be flexible!

Deterioration of Design
  Continuous changes cause bugs
  Solution:
    Make SW flexible (e.g. use a framework)
    Training
    Don't rush
    Use Quality Assurance

Political Risks
  Some folks might not like the requirements
  They might not understand the project or why you are using SW
  Might not understand why it takes time

  Solution: Communication through meetings, marketing, and negotiation