Example of DFD for Online Store (Data Flow Diagram)

This example was redesigned from the Wikipedia file: LastResortHotel BookRoom Process.png. [en.wikipedia.org/ wiki/ File:LastResortHotel_ BookRoom_ Process.png]
This file is licensed under the Creative Commons Attribution-ShareAlike 3.0 License. [creativecommons.org/ licenses/ by-sa/ 3.0/ ]
"Event partitioning is an easy-to-apply systems analysis technique that helps the analyst organize requirements for large systems into a collection of smaller, simpler, minimally-connected, easier-to-understand ‘mini systems’ / use cases. ...
Defining requirements.
Single process in a fictitious hotel using data flow diagram notation.
Single use case in a fictitious hotel using use case diagram notation.
This approach helps the analyst to decompose the system into ‘mentally bite-sized’ mini-systems using events that require a planned response. The level of detail of each response is at the level of ‘primary use cases’. Each planned response may be modelled using DFD notation or as a single use case using use case diagram notation.
The basic flow within a process or use case can usually be described in a relatively small number of steps, often fewer than twenty or thirty, possibly using something like ‘structured English’. Ideally, all of the steps would be visible all at once (often a page or less). The intention is to reduce one of the risks associated with short-term memory, namely, forgetting what is not immediately visible (‘out of sight, out of mind’). ...
Single process in a fictitious hotel using data flow diagram notation." [Event partitioning. Wikipedia]
The DFD example "Last resort hotel book room process" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the Data Flow Diagrams solution from the Software Development area of ConceptDraw Solution Park.

This example of a Top Level Context Diagram for an information system management process was redesigned from the Wikipedia file: IDEF Top-Level Context Diagram.jpg. [en.wikipedia.org/ wiki/ File:IDEF_ Top-Level_ Context_ Diagram.jpg]
"Graphical notation.
IDEF0 is a model that consists of a hierarchical series of diagrams, text, and glossary cross referenced to each other. The two primary modeling components are:
(1) functions (represented on a diagram by boxes), and
(2) data and objects that interrelate those functions (represented by arrows).
... the position at which the arrow attaches to a box conveys the specific role of the interface. The controls enter the top of the box. The inputs, the data or objects acted upon by the operation, enter the box from the left. The outputs of the operation leave the right-hand side of the box. Mechanism arrows that provide supporting means for performing the function join (point up to) the bottom of the box.
The IDEF0 process.
The IDEF0 process starts with the identification of the prime function to be decomposed. This function is identified on a “Top Level Context Diagram,” that defines the scope of the particular IDEF0 analysis. ... From this diagram lower-level diagrams are generated." [IDEF0. Wikipedia]
The IDEF0 diagram example "Top-level context diagram" was created using the ConceptDraw PRO diagramming and vector drawing software extended with the IDEF0 Diagrams solution from the Software Development area of ConceptDraw Solution Park.