System Perspectives

Systems use a variety of means to organize their parts and coordinate interactions. Uses include the following.

structure parts and concerns
prioritize concerns
evaluate approaches

This page surveys the following strategies.

Logical: how the parts and processes depends logically
Design Aspects: the issues addressed in design and specification
Programming Level: skills and focus of programming a systems

Refer to the bibliography for more details.

Logical

Decomposes the systems into logical levels.
Outer levels depend and build on the inner levels.
Changes tend to occur more frequently at the outer levels.
Ideally, a change in technology, say a new sales force automation tool, will not force changes in business objects.

Objects: The basic concepts the enterprise deals with and how they relate to each other.

Process: How the enterprise transforms the objects to accomplish its goals.

Tools: The technology used to implement the process.

Procedure: Specific ways that the tools are used to accomplish the processes.

Example

Objects	Customers, orders, and products. exactly one customer to an order.
Process	Verify inventory. Verify payment befor shipment.
Tools	Data base. Multicolor, Paper form with .
Procedure	Customer gets yellow copy. exactly one customer to an order.

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Design Aspects

The following model identifies three basic aspects of an entity's design.

Architecture describes the top-level form or structure with an emphasis on function.

Identifies functions, their groupings, and their interactions.
Addresses how users think of the system
Documentation includes Functional block diagrams.

Implementation describes theoretical and mechanistic aspects in terms of functional units and processes.

identifies subsystems, technology, operating principles, interfaces, etc.
Documentation includes Schematic block diagrams.

Realization describes the concrete and physical aspects in terms of specific measurable parameters

identifies specific components, parts, physical layout, tolerances, data representation, etc
Documentation includes Detail drawings. blue prints.

Development methodologies tend to focus on firming successive aspects

Mission/business analysis focuses on architecture.
Preliminary desing focuses on implementation.
Detail design focuses on on realization.

Example

Architecture	Three hands rotate about a circular face. Hands indicate hours, minutes, seconds.
Implementation	Quartz crystal for timing. Power from a battery. Gears control movement of hands.
Realization	Face is pearlly white. Battery is CR03025. Detail drawing.

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Programming

The following model identifies basic configuring an application and its components. Operator the end user.

configures application to realize enterprise procedures.
done by end user.
requires detail expertise in business procedure

install application to accomplish enterprise procedures.
done by application specialist.
requires expertise in application and understanding of procedures

integrates and configure technology to implement process and objects.
done by end user.
requires broad and detailed understanding of objects, process, techology, and systems

realize detail technical functions.
done by technology specialists.
requires expertise in technology

Example

Operational	Search parameters. Scripts.
Application	GUI layouts Data base connections
System	Data base schema. Widget interactions. Services.
Technology	Data base engine. GUI widgets. Device drivers

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Architecture	describes the top-level form or structure with an emphasis on function. Identifies functions, their groupings, and their interactions. Addresses how users think of the system Documentation includes Functional block diagrams.
Implementation	describes theoretical and mechanistic aspects in terms of functional units and processes. identifies subsystems, technology, operating principles, interfaces, etc. Documentation includes Schematic block diagrams.
Realization	describes the concrete and physical aspects in terms of specific measurable parameters identifies specific components, parts, physical layout, tolerances, data representation, etc Documentation includes Detail drawings. blue prints.