# @mermaid-js/mermaid-zenuml MermaidJS plugin for ZenUML integration - A powerful sequence diagram rendering engine. > A Sequence diagram is an interaction diagram that shows how processes operate with one another and in what order. Mermaid can render sequence diagrams with [ZenUML](https://zenuml.com). Note that ZenUML uses a different syntax than the original Sequence Diagram in mermaid. ```mermaid zenuml BookLibService.Borrow(id) { User = Session.GetUser() if(User.isActive) { try { BookRepository.Update(id, onLoan, User) receipt = new Receipt(id, dueDate) } catch (BookNotFoundException) { ErrorService.onException(BookNotFoundException) } finally { Connection.close() } } return receipt } ``` ## Installation ### With bundlers ```sh npm install @mermaid-js/mermaid-zenuml ``` ```ts import mermaid from 'mermaid'; import zenuml from '@mermaid-js/mermaid-zenuml'; await mermaid.registerExternalDiagrams([zenuml]); ``` ### With CDN ```html ``` > [!NOTE] > ZenUML uses experimental lazy loading & async rendering features which could change in the future. ## Basic Usage Once the plugin is registered, you can create ZenUML diagrams using the `zenuml` syntax: ```mermaid zenuml Controller.Get(id) { Service.Get(id) { item = Repository.Get(id) if(item) { return item } else { return null } } return result } ``` ## ZenUML Syntax Reference ### Participants The participants can be defined implicitly as in the first example on this page. The participants or actors are rendered in order of appearance in the diagram source text. Sometimes you might want to show the participants in a different order than how they appear in the first message. It is possible to specify the actor's order of appearance by doing the following: ```mermaid zenuml title Declare participant (optional) Bob Alice Alice->Bob: Hi Bob Bob->Alice: Hi Alice ``` ### Annotators If you specifically want to use symbols instead of just rectangles with text you can do so by using the annotator syntax to declare participants as per below. ```mermaid zenuml title Annotators @Actor Alice @Database Bob Alice->Bob: Hi Bob Bob->Alice: Hi Alice ``` Available annotators include: - `@Actor` - Human figure - `@Database` - Database symbol - `@Boundary` - Boundary symbol - `@Control` - Control symbol - `@Entity` - Entity symbol - `@Queue` - Queue symbol ### Aliases The participants can have a convenient identifier and a descriptive label. ```mermaid zenuml title Aliases A as Alice J as John A->J: Hello John, how are you? J->A: Great! ``` ## Messages Messages can be one of: 1. Sync message 2. Async message 3. Creation message 4. Reply message ### Sync message You can think of a sync (blocking) method in a programming language. ```mermaid zenuml title Sync message A.SyncMessage A.SyncMessage(with, parameters) { B.nestedSyncMessage() } ``` ### Async message You can think of an async (non-blocking) method in a programming language. Fire an event and forget about it. ```mermaid zenuml title Async message Alice->Bob: How are you? ``` ### Creation message We use `new` keyword to create an object. ```mermaid zenuml new A1 new A2(with, parameters) ``` ### Reply message There are three ways to express a reply message: ```mermaid zenuml // 1. assign a variable from a sync message. a = A.SyncMessage() // 1.1. optionally give the variable a type SomeType a = A.SyncMessage() // 2. use return keyword A.SyncMessage() { return result } // 3. use @return or @reply annotator on an async message @return A->B: result ``` The third way `@return` is rarely used, but it is useful when you want to return to one level up. ```mermaid zenuml title Reply message Client->A.method() { B.method() { if(condition) { return x1 // return early @return A->Client: x11 } } return x2 } ``` ## Advanced Features ### Nesting Sync messages and Creation messages are naturally nestable with `{}`. ```mermaid zenuml A.method() { B.nested_sync_method() B->C: nested async message } ``` ### Comments It is possible to add comments to a sequence diagram with `// comment` syntax. Comments will be rendered above the messages or fragments. Comments on other places are ignored. Markdown is supported. ```mermaid zenuml // a comment on a participant will not be rendered BookService // a comment on a message. // **Markdown** is supported. BookService.getBook() ``` ### Loops It is possible to express loops in a ZenUML diagram. This is done by any of the following notations: 1. while 2. for 3. forEach, foreach 4. loop ```zenuml while(condition) { ...statements... } ``` Example: ```mermaid zenuml Alice->John: Hello John, how are you? while(true) { John->Alice: Great! } ``` ### Alt (Alternative paths) It is possible to express alternative paths in a sequence diagram. This is done by the notation ```zenuml if(condition1) { ...statements... } else if(condition2) { ...statements... } else { ...statements... } ``` Example: ```mermaid zenuml Alice->Bob: Hello Bob, how are you? if(is_sick) { Bob->Alice: Not so good :( } else { Bob->Alice: Feeling fresh like a daisy } ``` ### Opt (Optional) It is possible to render an `opt` fragment. This is done by the notation ```zenuml opt { ...statements... } ``` Example: ```mermaid zenuml Alice->Bob: Hello Bob, how are you? Bob->Alice: Not so good :( opt { Bob->Alice: Thanks for asking } ``` ### Parallel It is possible to show actions that are happening in parallel. This is done by the notation ```zenuml par { statement1 statement2 statement3 } ``` Example: ```mermaid zenuml par { Alice->Bob: Hello guys! Alice->John: Hello guys! } ``` ### Try/Catch/Finally (Break) It is possible to indicate a stop of the sequence within the flow (usually used to model exceptions). This is done by the notation ``` try { ...statements... } catch { ...statements... } finally { ...statements... } ``` Example: ```mermaid zenuml try { Consumer->API: Book something API->BookingService: Start booking process } catch { API->Consumer: show failure } finally { API->BookingService: rollback status } ``` ## Contributing This package is part of the [Mermaid](https://github.com/mermaid-js/mermaid) project. See the main repository for contributing guidelines. ## Contributors - [Peng Xiao](https://github.com/MrCoder) - [Sidharth Vinod](https://sidharth.dev) - [Dong Cai](https://github.com/dontry) ## License MIT ## Links - [ZenUML Official Website](https://zenuml.com) - [Mermaid Documentation](https://mermaid.js.org) - [GitHub Repository](https://github.com/mermaid-js/mermaid)