Building Blocks
Context diagrams can be developed with the use of two types of building blocks:
- Entities (Actors): labeled boxes; one in the center representing the system, and around it multiple boxes for each external actor
- Relationships: labeled lines between the entities and system
For example, "customer places order." Context diagrams can also use many different drawing types to represent external entities. They can use ovals, stick figures, pictures, clip art or any other representation to convey meaning. Decision trees and data storage are represented in system flow diagrams.
A context diagram can also list the classifications of the external entities as one of a set of simple categories (Examples:), which add clarity to the level of involvement of the entity with regards to the system. These categories include:
- Active: Dynamic external entities which frequently initiate events to achieve some goal or purpose (Examples: "Article readers" or "customers").
- Passive: Static external entities which infrequently interact with the system (Examples: "Article editors" or "database administrator").
- Cooperative: Predictable external entities which are used by the system to bring about some desired outcome (Examples: "Internet service providers" or "shipping companies").
- Autonomous (Independent): External entities which are separated from the system, but affect the system indirectly, by means of imposed constraints or similar influences (Examples: "regulatory committees" or "standards groups").
Read more about this topic: System Context Diagram
Famous quotes containing the words building and/or blocks:
“Are we not madder than those first inhabitants of the plain of Sennar? We know that the distance separating the earth from the sky is infinite, and yet we do not stop building our tower.”
—Denis Diderot (1713–1784)
“In any case, raw aggression is thought to be the peculiar province of men, as nurturing is the peculiar province of women.... The psychologist Erik Erikson discovered that, while little girls playing with blocks generally create pleasant interior spaces and attractive entrances, little boys are inclined to pile up the blocks as high as they can and then watch them fall down: “the contemplation of ruins,” Erikson observes, “is a masculine specialty.””
—Joyce Carol Oates (b. 1938)