Data Flow Models / Diagrams
Context
Context
Levels in Data Flow Diagrams (DFD) geeksforgeeks
Also known as a context diagram. An abstraction view, showing the system as a single process with its relationship to external entities. It represent the entire system as single bubble with input and output data indicated by incoming/outgoing arrows. Used to depict scope and interfaces.
The Context Diagram should mark the Software To-Be-Developed in the center, without any details, as a black box or circle, and all its interfaces with entities external to this software, showing just interfaces with descriptions what kind of information they carry in each direction, from the software towards the environment and back, from the environment to the software.
Normally, a Context Diagram has to include the interfaces featuring all interactions of the Software To-Be-Developed with the external environment. This includes the description of all signals, which are exchanged between the software and the environment.
http://itech.fgcu.edu/faculty/zalewski/CEN4935/RulesOfWritingSRS.pdf
In a level 1 DFD, the context diagram is decomposed into multiple bubbles/processes. In this level we highlight the main functions of the system and breakdown the high level process of the level 0 DFD into subprocesses.
A level 2 DFD goes one step deeper into parts of the level 1 DFD. It can be used to plan or record the specific/necessary detail about the system’s functioning.
Data Flow Diagram SmartDraw
and watch What is a DFD? video (4:13)
Discovering Requirements section 4.3
System context diagram wikipedia
Visio
How to Make Data Flow Diagrams (DFD) with SmartDraw video (4:32)
StarUML - you can use the free evaluation version which will include a watermark
draw.io - integrates with Jira and Trello