The flow chart

introduce

Flow chart can also be called input-output diagram, mainly used to describe an input-output process, suitable for project development in the process of drawing the specific logical steps (a series of actions), how to achieve the final result step by step, and then programming.

The symbol of

Commonly used symbols

Flow chart structure

Sequential structure

Choose structure

Loop structure

Draw the considerations in the flow chart

1. To improve the logic of your flowchart, follow the sequence from left to right and top to bottom.

2. A process begins with a start character and ends with an end character. The opening symbol may appear only once, and the closing symbol may appear more than once. If the flow is clear enough, omit the beginning and end symbols.

3. Diamond as a judgment symbol, there must be “yes and no (or Y and N)” two processing results, meaning that the diamond judgment box must have two arrows flow out; “Yes (or Y)” is generally used to judge the inflow and outflow of the upper and lower ends of the symbol, and “no (or Y)” is used to judge the inflow and outflow of the left and right ends.

4. Within the same flow chart, the symbol size should be consistent, and the connecting line should not cross, and the connecting line should not bend without reason

5. If the process relationship is parallel, the process needs to be placed at the same height.

6. Annotations should be used where necessary to clearly illustrate the process, annotated with special notation.

7. The process shall be drawn with a single entry and a single exit

8. There should be only one arrow indicating the same path

The sample

This is a flow chart of the rental car login system

The sequence diagram

introduce

Sequence diagram, also called sequence diagram, sequential diagram or sequence diagram, is a KIND of UML interaction diagram. It shows dynamic collaboration between multiple objects by describing the chronological order in which messages are sent between them. Suitable for describing the process of interactive behavior, such as the process from scanning posters to filling in identity information and then buying products to create a sequence diagram.

Constituent elements

• role

  System roles, which can be people, machines, other systems, subsystems; Represented by small humanoid ICONS in sequence diagrams

• object

• Lifelines are represented in a sequence diagram as a dotted line running down from the object icon, indicating the time of the object’s existence

• Control the focus

• Message messages are typically classified as Synchronous Message, Asynchronous Message, and Return Message.

  • The sender of the message passes control to the receiver of the message and then stops the activity, waiting for the receiver of the message to relinquish or return control. Used to indicate the meaning of synchronization;
  • The message sender passes the signal through the message to the message receiver and then continues its activities without waiting for the receiver to return the message or take control. The receiver and sender of an asynchronous message work concurrently.
  • The return message represents a return from the procedure call.

• A self-associated message represents a call to a method itself or a method within an object that calls another method

• Combination fragment

  

  • Choice, equivalent to if else.
  • Option that contains a sequence that may or may not occur
  • Loop: the number of times a fragment is repeated, indicating the condition under which the fragment is repeated in the criticality
  • Parallel, parallel processing, events in fragments can be interleaved

The sample

This is a student in the educational administration system to query their personal course results of the flow chart drawing

Use case diagram

introduce

Use-case diagrams are often used to express requirements when writing requirements specification. They are used to explain the relationship between users and system functional units in requirements to development and test colleagues.

Use case diagram structure

• participants

• Use cases

  A use case is a functional unit visible outside the system. It is a set of a series of activities from the beginning to the end of a certain participant doing something in the system, and the observable and meaningful results should be returned at the end. It also includes all possible branches. Specific use cases are described in the use case properties.

  • Use cases are verb-object; For example, login account
  • Use cases are independent of each other
  • Use cases are initiated by actors
  • There are observable execution results

• The relationship between actors and use cases

  • correlation

    • Relationship description: Represents the relationship between the actor and the use case
    • Presentation form: connected in a straight line
    • Example: A user logs in to the system

    

  • Induction (generalization) relations

    • Relationship description: Represents relationships between participants and between use cases
    • Presentation form: arrows point from child actor (child use case) to parent actor (base use case). General parent actor (base use case) is more abstract than child actor (child use case)
    • For example: VIP members and ordinary users, summarized as users; Account login and wechat login can also be summarized as login system.

    

  • Contains the relationship

    • Relationship description: Represents the relationship between use cases
    • Presentation: Represented by an arrow with “include” pointing from the base use case to the include use case
    • Example: During account login, users can enter the account, password, and confirm login

    

  • Develop relationships

    • Relationship description: Represents the relationship between use cases; Enhancements to base use cases for extended use cases; An extension use case is a use case that is executed only when certain conditions arise
    • Presentation form: represented by an arrow with “extension”, from extension to base use cases
    • For example, a user forgets the password during login

    

  • dependencies

    • Relationship description: Represents the relationship between use cases; One use case depends on the execution of another use case during the execution of an activity
    • Presentation form: connected in a straight line
    • For example: Users can view the home page information only after logging in to the system
    • Supplementary note: A use case depends on B use case, A use case either returns results after using B use case execution, or uses B use case to perform some functions. Dependencies are similar to inclusion relationships in that other use cases are invoked to complete part of the task during use case execution.

    

  • annotation

    For some use cases supported by special conditions, you can add comments to explain them. For example, after VIP users and common users log in to the system, the menus, data, and even system operations are different. In this case, you can add comments to application cases to emphasize the special requirements of this use case.

    

  • The subsystem

    Relationship description: Used to emphasize the strong relevance of some use cases, for example, the portal contains system login, home page information display, etc.

    

    \

The resources

1. Quick Learning flow chart
2. Learn sequence diagrams quickly
3. Uml use case drawing

tool

Visual Paradigim Online processOn recommends using Visual Paradigim Online, this drawing is more standard, in addition to the use of more convenient and smooth