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Sequence Diagrams

Visualize interactions between different actors over time

Quick Start

Basic Syntax

sequenceDiagram
participant A as Alice
participant B as Bob
A->>B: Hello!
B-->>A: Hi there!

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Message Types

A->>B: Message
Solid arrow (synchronous call)
A-->>B: Message
Dashed arrow (asynchronous response)
A-)B: Message
Open arrow (fire and forget)
A-x B: Message
Cross arrow (lost message)
A->>+B: Message
Activate participant
A-->>-B: Message
Deactivate participant

Complete Examples

Basic Sequence Diagram
Simple interaction between two participants

Code

sequenceDiagram
    participant A as Alice
    participant B as Bob
    
    A->>B: Hello Bob, how are you?
    B-->>A: Great!
    A-)B: See you later!

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Use Case

Perfect for documenting simple API calls or basic user interactions

Complex API Flow
Multiple participants with loops and conditions

Code

sequenceDiagram
    participant C as Client
    participant S as Server
    participant DB as Database
    participant Cache as Redis
    
    C->>+S: Login Request
    S->>+DB: Validate User
    DB-->>-S: User Data
    
    alt User Valid
        S->>+Cache: Store Session
        Cache-->>-S: Session ID
        S-->>C: Login Success
    else Invalid User
        S-->>C: Login Failed
    end
    
    Note over C,S: User is now authenticated
    
    loop Every 30 minutes
        S->>Cache: Refresh Session
    end

Preview

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Use Case

Ideal for complex system interactions with multiple services