System Modelling using UML

Source - It is where the system functionalities is came from and driven by the stakeholders. Sources of requirements are the origins where the corresponding business process is initiated. By this concept, one has to trace from a requirement back to its origins to see who is involved in its initiation. Bet it a person, an organization or an external entity that initiate some action and system responds back by completing that action

Sink - It is an output from the source to be consumed by the consumers or end-user. This are logical ends of requirements, or where all the requirements are consumed. For example, we may consider a user of a software application that retrieves a report from the system. In this case, user when reviews the report, becomes the sink of that report. Thus when analyzing the sink of the requirement of implementing a report, the analyst would naturally point towards the user who would get that report.

State Transition Diagram - Commonly known as STD's in Software term. describe all of the states that an object can have, the events under which an object changes state (transitions), the conditions that must be fulfilled before the transition will occur (guards), and the activities undertaken during the life of an object (actions).

Data Flow Diagram -  Commonly known as DFD. It is a presentation of flow of data in the system in parallel. It helps in developing an understanding of system's functionality. It describes data origination, transformation and consumption in a system.

Context Diagram - Also referred to as the Level 0 Data Flow Diagram, the Context diagram is the highest level in a Data Flow Diagram. It is a tool popular among Business Analysts who use it to understand the details and boundaries of the system to be designed in a project. It points out the flow of information between the system and external components.