Activity diagram

Activity diagrams are widely used in system analysis and design to model the behavior of a system, particularly for business processes and workflows. In system analysis and design, activity diagrams are used to model the steps or activities involved in a particular process or use case scenario.

Swimlane notation (AD)


Activity diagrams in system analysis and design typically have the following characteristics:


  • Start and end points: The diagram should begin with a start point, which represents the initiation of the process or use case, and end with an end point, which represents the completion of the process or use case.
  • Actions: The actions or steps involved in the process or use case should be represented by rectangular boxes, and the actions should be organized in a logical sequence.
  • Control flow: The flow of control between actions should be represented by arrows. Arrows should indicate the order in which actions are performed and the conditions that determine the path of the process or use case.
  • Decisions: Decision points are represented by diamond shapes and indicate a choice between two or more possible paths. Each decision point should be labeled with the condition that determines the path.
  • Loops: Loops are used to represent iterative steps in a process or use case, and are represented by arrows that loop back to a previous step.
  • Subprocesses: A subprocess represents a sequence of actions that can be treated as a separate process or use case. A subprocess is represented by a rectangle with its own start and end points.

Activity diagrams in system analysis and design are useful for modeling and understanding complex business processes or workflows, and for identifying potential issues or bottlenecks in the process. They can also be used to communicate the process or use case to stakeholders and to aid in the development of the system. Activity diagrams can be used in conjunction with other diagrams, such as use case diagrams and sequence diagrams, to provide a comprehensive view of the system.


Component Diagram

Component diagrams are a type of diagram used in system analysis and design to illustrate the components, interfaces, and dependencies of a system. They show how the different parts of a system are connected and how they interact with each other to form a cohesive whole.



The major elements of UML component diagram - component, provided interface, required interface, port, connectors. (CD)

Component diagrams consist of the following components:

  • Components: These are the modular parts of the system, such as classes, libraries, and executables. Each component has a name and a list of interfaces that it provides and requires.
  • Interfaces: These are the connectors between components, specifying the services that a component provides and the services that it requires from other components.
  • Dependencies: These show the relationships between components, indicating which components depend on which other components. Dependencies can be of different types, such as "uses", "requires", or "provides".
  • Connectors: These are the mechanisms by which interfaces are implemented, such as method calls, messages, or procedure calls.
  • Ports: These are the access points for interfaces, representing the points at which a component interacts with other components.

Component diagrams are useful for understanding the structure and organization of a system, and for identifying potential issues related to dependencies and interfaces. They can also be used to aid in system design and development, as they provide a high-level view of the system's architecture and can help in identifying opportunities for reuse and modularization.

Component diagrams can be used in conjunction with other diagrams, such as class diagrams and deployment diagrams, to provide a comprehensive view of the system.

Deployment Diagram

Deployment diagrams are a type of diagram used in system analysis and design to illustrate the physical architecture of a system. They show how the different components of a system are deployed on hardware or software environments, such as servers, workstations, or cloud services.

Specification level deployment diagram - web application deployed to Tomcat JSP server and database schemas - to database system. (DD)


Deployment diagrams consist of the following components:

  • Nodes: These represent the hardware or software environments on which components are deployed, such as servers, workstations, or cloud services.
  • Components: These are the modular parts of the system, such as classes, libraries, and executables. Each component has a name and a list of interfaces that it provides and requires.
  • Artifacts: These are the physical representations of components, such as files, executables, or libraries.
  • Communication paths: These show the connections between nodes and the components that are deployed on them, indicating how the components communicate with each other.
  • Dependencies: These show the relationships between components and nodes, indicating which components depend on which nodes.

Deployment diagrams are useful for understanding the physical architecture of a system, and for identifying potential issues related to hardware or software dependencies, performance, or scalability. They can also be used to aid in system design and development, as they provide a high-level view of the system's physical architecture and can help in identifying opportunities for optimization and resource allocation.


Deployment diagrams can be used in conjunction with other diagrams, such as component diagrams and sequence diagrams, to provide a comprehensive view of the system.