Systems Engineering of Software-Intensive Systems

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Systems Engineering of Software-Intensive Systems
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What is Systems Engineering?- According to the
International Council on Systems Engineering

• Systems engineering is an interdisciplinary
  approach and means to enable the realization of
  successful systems. It focuses on defining
  customer needs and required functionality early
  in the development cycle, documenting
  requirements, then proceeding with design
  synthesis and system validation while considering
  the complete problem
• Operations
• Performance
• Test
• Manufacturing
• Cost and Schedule
• Training and Support
• Disposal

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What is Systems Engineering? (Contd) -
According to the International Council on Systems
Engineering

• Systems engineering integrates all the
  disciplines and specialty groups into a team
  effort forming a structured development process
  that proceeds from concept to production to
  operation. Systems Engineering considers both
  the business and the technical needs of all
  customers with the goal of providing a quality
  product that meets the user needs.

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Principles of Systems Engineering

• Know the problem, know the customer, and know the
  consumer.
• Use effectiveness criteria based on needs to make
  the system decisions.
• Establish and manage requirements.
• Identify and assess alternatives so as to
  converge on a solution.
• Verify and validate requirements and solution
  performance.
• Maintain the integrity of the system.
• Use an articulated and documented process.
• Manage against a plan.

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The Decomposition of Complex Systems

• The system is successively refined until
• The distribution and partitioning of
  functionality are optimized to achieve the
  overall functionality of the system with minimal
  costs and maximum flexibility.
• Each subsystem can be defined, designed, and
  built by a small, or at least modest-sized team.

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The Decomposition of Complex Systems (Contd)

• Each subsystem can be manufactured within the
  physical constraints and technologies of the
  available manufacturing processes.
• Each subsystem can be reliably tested as a
  subsystem, subject to the availability of
  suitable fixtures and harnesses that simulate the
  interfaces to the other subsystems.
• Appropriate deference is given to the physical
  domain the size, weight, location, and
  distribution of the subsystems that has been
  optimized in the overall context.

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Derived Requirements

• Subsystem requirements are those that must be
  imposed on the subsystems themselves but do not
  necessarily provide a direct benefit to the end
  user.
• Interface requirements may arise when the
  subsystems need to communicate with one another
  to accomplish an overall result. They will need
  to share data, power, or a useful computing
  algorithm.

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Changes in Systems Engineering

• Software, not hardware, determines the ultimate
  functionality of the system and the success of
  the system in the end users hands and in the
  marketplace.
• Software, not hardware, consumes the majority of
  the costs of research and systems development.
• Software, not hardware, is on the critical path
  and, therefore, ultimately determines when the
  system goes to the marketplace.

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Changes in Systems Engineering (Contd)

• Software, not hardware, absorbs most of the
  changes that occur during development and can
  even evolve to meet the changing needs of a
  system deployed in the field.
• The cost of software development and maintenance,
  taken in the aggregate and amortized over the
  full life of the produce, has become material to,
  or in some cases equal to or greater than, the
  contribution of hardware costs of goods sold to
  that holy grail of systems manufacturers total
  manufacturing costs.

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Systems Engineering Recommendations

• Develop, understand, and maintain the high-level
  requirements and use cases that span the
  subsystems and that describe the overall system
  functionality.
• Do the best possible job of partitioning and
  isolating functionality within subsystems.
• If possible, develop software as a whole, not as
  several individual pieces, one for each subsystem

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Systems Engineering Recommendations (Contd)

• When coding the interfaces, use common code on
  both sides of the interface.
• Define interface specifications that can do more
  than would be necessary to simply meet the known
  conditions
• See whether you can find one of those
  graybeards to help you with your systems
  engineering

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Case Study Systems Engineering for HOLIS

• HOLIS stands for Home Lighting automation System.
• This is a proposed new product for a company
  called Lumenations in the professional theater
  marketplace.
• The goal is to acquire new customers by offering
  a new product.

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HOLIS Well-Understood User Needs

• HOLIS will need to support soft key switches
  individually programmable key switches used to
  activate the lighting features in various rooms.
• Homeowners have requested a means to program
  HOLIS from a remote center so they can simply
  call in their needs and not be bothered with
  programming HOLIS at all.

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HOLIS Case Study Well -Understood User Needs
(Contd)

• Other prospective buyers have requested that
  HOLIS be programmable from their home PCs and
  that they be provided with the ability to do all
  the installation, programming, and maintenance
  themselves.
• Still others have requested that the system
  provide a simple, push-button, control panel-type
  interface they can use to change HOLIS
  programming, vacation settings, and so on,
  without having to use a PC.
• HOLIS needs to provide an emergency-contact
  system of some kind.

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Problem Statement for Lumenations
Element Description
The problem of . . . Slowing growth in the companys core professional theater marketplaces.
Affects . . . The company, its employees, and its shareholders.
And results in . . . Unacceptable business performance and lack of substantive opportunities for growth in revenue and profitability.
Benefits of a solution . . . Involving new products and a potential new marketplace for the companys products and services include Revitalization of the company and its employees Increased loyalty and retention of the companys distributors Higher revenue growth and profitability Upturn in the companys stock price
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Problem Statement for the Homeowner
Element Description
The problem of . . . The lack of product choices, limited functionality, and the high cost of existing home lighting automation systems.
Affects . . . The homeowners of high-end residential systems.
And results in . . . Unacceptable performance of the purchased systems or, more often than not, a decision not to automate.
Benefits of a solution . . . That comprised the right lighting automation solution could include Higher homeowner satisfaction and pride of ownership Increased flexibility and usability of the residence Improved safety, comfort, and convenience
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Problem Statement for the Distributor
Element Description
The problem of . . . The lack of product choices, limited functionality, and the high cost of existing home lighting automation systems.
Affects . . . The distributors and builders of high-end residential systems.
And results in . . . Few opportunities for marketplace differentiation and no new opportunities for higher-margin products.
Benefits of a solution . . . That comprised the right lighting automation solution could include Differentiation Higher revenues and higher profitability Increased market share