Command Flow

Command Flow

The Command Flow diagram illustrates how commands flow through the system, from command handlers to repositories, generating events along the way. This provides a detailed view of the system’s implementation architecture following the Command Query Responsibility Segregation (CQRS) pattern.

What is Command Flow?

The Command Flow diagram shows:

• Command Handlers: Classes that process commands
• Commands: User actions or system operations
• Domain Events: Facts that have happened in the system
• Repositories: Data storage components
• Flow: How commands flow through the system to generate events

The Bartendie Command Flow

The diagram below shows the command flow for the Bartendie system:

flowchart TD
    %% Command Handlers
    subgraph Command Handlers
        %% Event Planning Handlers
        CH1[ScheduleEventHandler]
        CH2[DefineEventThemeHandler]
        CH23[CreateGuestListHandler]
        CH24[AddGuestHandler]
        CH25[RemoveGuestHandler]
        CH26[TrackGuestRSVPHandler]
        CH27[SetGuestPreferencesHandler]
        CH28[SetAttendanceEstimateHandler]
        
        %% Menu Handlers
        CH3[CreateMenuHandler]
        CH17[AddRecipeToMenuHandler]
        
        %% Inventory Handlers
        CH4[CheckInventoryHandler]
        CH5[GenerateShoppingListHandler]
        CH6[PurchaseSuppliesHandler]
        CH11[UpdateInventoryHandler]
        CH48[ScanProductBarcodeHandler]
        CH49[LookUpProductDataHandler]
        CH50[AddProductToInventoryHandler]
        CH51[UpdateProductLevelHandler]
        CH52[MarkProductEmptyHandler]
        CH53[AddProductToShoppingListHandler]
        CH29[RecalculateShoppingQuantitiesHandler]
        
        %% Bar Setup Handlers
        CH7[PrepareBarSetupHandler]
        CH8[CreateBatchedCocktailsHandler]
        CH9[ServeDrinksHandler]
        CH10[CollectGuestFeedbackHandler]
        
        %% Recipe Handlers
        CH12[CreateRecipeHandler]
        CH13[UpdateRecipeHandler]
        CH14[RateRecipeHandler]
        CH15[TagRecipeHandler]
        CH16[SearchRecipesHandler]
        CH38[DefineFlavorProfileHandler]
        CH39[AddIngredientProfileHandler]
        CH40[UpdateIngredientProfileHandler]
        CH41[CalculateRecipeBalanceHandler]
        CH42[SuggestBalancingIngredientsHandler]
        CH43[FilterByFlavorProfileHandler]
        CH44[CalculateBatchQuantitiesHandler]
        CH45[ScaleRecipeHandler]
        CH46[ConvertUnitsHandler]
        CH47[SaveBatchRecipeHandler]
        
        %% Tagging System Handlers
        CH18[CreateTagHandler]
        CH19[UpdateTagHandler]
        CH20[ApplyTagHandler]
        CH21[RemoveTagHandler]
        CH22[SearchByTagHandler]
        
        %% Equipment Handlers
        CH30[AddBarToolHandler]
        CH31[UpdateBarToolHandler]
        CH32[RemoveBarToolHandler]
        CH33[AddEquipmentHandler]
        CH34[UpdateEquipmentHandler]
        CH35[RemoveEquipmentHandler]
        CH36[LinkToolsToRecipeHandler]
        CH37[CheckToolAvailabilityHandler]
        
        %% Venue Management Handlers
        CH54[CreateVenueHandler]
        CH55[UpdateVenueHandler]
        CH56[AddStorageHandler]
        CH57[UpdateStorageHandler]
        CH58[RemoveStorageHandler]
        CH59[AddBarHandler]
        CH60[UpdateBarHandler]
        CH61[RemoveBarHandler]
    end

    %% Commands
    %% Event Planning Commands
    C1[/"Schedule Event"/]
    C2[/"Define Event Theme"/]
    C23[/"Create Guest List"/]
    C24[/"Add Guest"/]
    C25[/"Remove Guest"/]
    C26[/"Track Guest RSVP"/]
    C27[/"Set Guest Preferences"/]
    C28[/"Set Attendance Estimate"/]
    
    %% Menu Commands
    C3[/"Create Menu"/]
    C17[/"Add Recipe To Menu"/]
    
    %% Inventory Commands
    C4[/"Check Inventory"/]
    C5[/"Generate Shopping List"/]
    C6[/"Purchase Supplies"/]
    C11[/"Update Inventory"/]
    C48[/"Scan Product Barcode"/]
    C49[/"Look Up Product Data"/]
    C50[/"Add Product To Inventory"/]
    C51[/"Update Product Level"/]
    C52[/"Mark Product Empty"/]
    C53[/"Add Product To Shopping List"/]
    C29[/"Recalculate Shopping Quantities"/]
    
    %% Bar Setup Commands
    C7[/"Prepare Bar Setup"/]
    C8[/"Create Batched Cocktails"/]
    C9[/"Serve Drinks"/]
    C10[/"Collect Guest Feedback"/]
    
    %% Recipe Commands
    C12[/"Create Recipe"/]
    C13[/"Update Recipe"/]
    C14[/"Rate Recipe"/]
    C15[/"Tag Recipe"/]
    C16[/"Search Recipes"/]
    C38[/"Define Flavor Profile"/]
    C39[/"Add Ingredient Profile"/]
    C40[/"Update Ingredient Profile"/]
    C41[/"Calculate Recipe Balance"/]
    C42[/"Suggest Balancing Ingredients"/]
    C43[/"Filter By Flavor Profile"/]
    C44[/"Calculate Batch Quantities"/]
    C45[/"Scale Recipe"/]
    C46[/"Convert Units"/]
    C47[/"Save Batch Recipe"/]
    
    %% Tagging System Commands
    C18[/"Create Tag"/]
    C19[/"Update Tag"/]
    C20[/"Apply Tag"/]
    C21[/"Remove Tag"/]
    C22[/"Search By Tag"/]
    
    %% Equipment Commands
    C30[/"Add Bar Tool"/]
    C31[/"Update Bar Tool"/]
    C32[/"Remove Bar Tool"/]
    C33[/"Add Equipment"/]
    C34[/"Update Equipment"/]
    C35[/"Remove Equipment"/]
    C36[/"Link Tools To Recipe"/]
    C37[/"Check Tool Availability"/]

    %% Venue Management Commands
    C54[/"Create Venue"/]
    C55[/"Update Venue"/]
    C56[/"Add Storage"/]
    C57[/"Update Storage"/]
    C58[/"Remove Storage"/]
    C59[/"Add Bar"/]
    C60[/"Update Bar"/]
    C61[/"Remove Bar"/]

    %% Domain Events
    %% Event Planning Events
    E1{{EventScheduled}}
    E2{{ThemeDefined}}
    E23{{GuestListCreated}}
    E24{{GuestAdded}}
    E25{{GuestRemoved}}
    E26{{GuestRSVPUpdated}}
    E27{{GuestPreferencesSet}}
    E28{{AttendanceEstimateSet}}
    
    %% Menu Events
    E3{{MenuCreated}}
    E17{{RecipeAddedToMenu}}
    E45{{MenuBalanceAnalyzed}}
    
    %% Inventory Events
    E4{{InventoryChecked}}
    E5{{ShoppingListGenerated}}
    E6{{SuppliesPurchased}}
    E11{{InventoryUpdated}}
    E29{{ShoppingQuantitiesRecalculated}}
    E50{{ProductBarcodeScanned}}
    E51{{ProductDataRetrieved}}
    E52{{ProductAddedToInventory}}
    E53{{ProductLevelUpdated}}
    E54{{ProductMarkedEmpty}}
    E55{{ProductAddedToShoppingList}}
    
    %% Bar Setup Events
    E7{{BarSetupCompleted}}
    E8{{CocktailsBatched}}
    E9{{DrinkServed}}
    E10{{FeedbackCollected}}
    
    %% Recipe Events
    E12{{RecipeCreated}}
    E13{{RecipeUpdated}}
    E14{{RecipeRated}}
    E15{{RecipeTagged}}
    E16{{RecipesSearched}}
    E39{{FlavorProfileDefined}}
    E40{{IngredientProfileAdded}}
    E41{{IngredientProfileUpdated}}
    E42{{RecipeBalanceCalculated}}
    E43{{BalancingSuggestionsGenerated}}
    E44{{RecipesFilteredByProfile}}
    E46{{BatchQuantitiesCalculated}}
    E47{{RecipeScaled}}
    E48{{UnitsConverted}}
    E49{{BatchRecipeSaved}}
    
    %% Tagging System Events
    E18{{TagCreated}}
    E19{{TagUpdated}}
    E20{{TagApplied}}
    E21{{TagRemoved}}
    E22{{ItemsSearchedByTag}}
    
    %% Equipment Events
    E30{{BarToolAdded}}
    E31{{BarToolUpdated}}
    E32{{BarToolRemoved}}
    E33{{EquipmentAdded}}
    E34{{EquipmentUpdated}}
    E35{{EquipmentRemoved}}
    E36{{ToolsLinkedToRecipe}}
    E37{{ToolAvailabilityChecked}}
    E38{{ToolShortageIdentified}}

    %% Venue Management Events
    E56{{VenueCreated}}
    E57{{VenueUpdated}}
    E58{{StorageAdded}}
    E59{{StorageUpdated}}
    E60{{StorageRemoved}}
    E61{{BarAdded}}
    E62{{BarUpdated}}
    E63{{BarRemoved}}

    %% Repositories
    subgraph Repositories
        R1[(EventRepository)]
        R2[(MenuRepository)]
        R3[(RecipeRepository)]
        R4[(TagRepository)]
        R5[(InventoryRepository)]
        R6[(ShoppingListRepository)]
        R7[(BarSetupRepository)]
        R8[(GuestRepository)]
        R9[(FeedbackRepository)]
        R10[(FlavorProfileRepository)]
        R11[(EquipmentRepository)]
        R12[(BatchRecipeRepository)]
        R13[(ProductRepository)]
        R14[(VenueRepository)]
    end

    %% Command flows - Event Planning
    C1 --> CH1
    CH1 --> R1
    CH1 --> R14
    CH1 --> E1
    
    C2 --> CH2
    CH2 --> R1
    CH2 --> E2
    
    C23 --> CH23
    CH23 --> R8
    CH23 --> E23
    
    C24 --> CH24
    CH24 --> R8
    CH24 --> E24
    
    C25 --> CH25
    CH25 --> R8
    CH25 --> E25
    
    C26 --> CH26
    CH26 --> R8
    CH26 --> E26
    
    C27 --> CH27
    CH27 --> R8
    CH27 --> E27
    
    C28 --> CH28
    CH28 --> R1
    CH28 --> E28
    
    %% Command flows - Menu
    C3 --> CH3
    CH3 --> R1
    CH3 --> R2
    CH3 --> E3
    
    C17 --> CH17
    CH17 --> R2
    CH17 --> R3
    CH17 --> E17
    
    %% Command flows - Inventory
    C4 --> CH4
    CH4 --> R5
    CH4 --> E4
    
    C5 --> CH5
    CH5 --> R5
    CH5 --> R6
    CH5 --> E5
    
    C6 --> CH6
    CH6 --> R6
    CH6 --> E6
    
    C11 --> CH11
    CH11 --> R5
    CH11 --> E11
    
    C29 --> CH29
    CH29 --> R6
    CH29 --> E29
    
    C48 --> CH48
    CH48 --> E50
    
    C49 --> CH49
    CH49 --> R13
    CH49 --> E51
    
    C50 --> CH50
    CH50 --> R5
    CH50 --> R13
    CH50 --> E52
    
    C51 --> CH51
    CH51 --> R5
    CH51 --> R13
    CH51 --> E53
    
    C52 --> CH52
    CH52 --> R5
    CH52 --> R13
    CH52 --> E54
    
    C53 --> CH53
    CH53 --> R6
    CH53 --> R13
    CH53 --> E55
    
    %% Command flows - Bar Setup
    C7 --> CH7
    CH7 --> R7
    CH7 --> R14
    CH7 --> E7
    
    C8 --> CH8
    CH8 --> R3
    CH8 --> R7
    CH8 --> R12
    CH8 --> E8
    
    C9 --> CH9
    CH9 --> R5
    CH9 --> E9
    
    C10 --> CH10
    CH10 --> R9
    CH10 --> E10
    
    %% Command flows - Recipe
    C12 --> CH12
    CH12 --> R3
    CH12 --> E12
    
    C13 --> CH13
    CH13 --> R3
    CH13 --> E13
    
    C14 --> CH14
    CH14 --> R3
    CH14 --> E14
    
    C15 --> CH15
    CH15 --> R3
    CH15 --> R4
    CH15 --> E15
    
    C16 --> CH16
    CH16 --> R3
    CH16 --> E16
    
    C38 --> CH38
    CH38 --> R10
    CH38 --> E39
    
    C39 --> CH39
    CH39 --> R10
    CH39 --> E40
    
    C40 --> CH40
    CH40 --> R10
    CH40 --> E41
    
    C41 --> CH41
    CH41 --> R3
    CH41 --> R10
    CH41 --> E42
    
    C42 --> CH42
    CH42 --> R3
    CH42 --> R10
    CH42 --> E43
    
    C43 --> CH43
    CH43 --> R3
    CH43 --> R10
    CH43 --> E44
    
    C44 --> CH44
    CH44 --> R3
    CH44 --> R12
    CH44 --> E46
    
    C45 --> CH45
    CH45 --> R3
    CH45 --> R12
    CH45 --> E47
    
    C46 --> CH46
    CH46 --> E48
    
    C47 --> CH47
    CH47 --> R12
    CH47 --> E49
    
    %% Command flows - Tagging System
    C18 --> CH18
    CH18 --> R4
    CH18 --> E18
    
    C19 --> CH19
    CH19 --> R4
    CH19 --> E19
    
    C20 --> CH20
    CH20 --> R4
    CH20 --> E20
    
    C21 --> CH21
    CH21 --> R4
    CH21 --> E21
    
    C22 --> CH22
    CH22 --> R4
    CH22 --> E22
    
    %% Command flows - Equipment
    C30 --> CH30
    CH30 --> R11
    CH30 --> E30
    
    C31 --> CH31
    CH31 --> R11
    CH31 --> E31
    
    C32 --> CH32
    CH32 --> R11
    CH32 --> E32
    
    C33 --> CH33
    CH33 --> R11
    CH33 --> E33
    
    C34 --> CH34
    CH34 --> R11
    CH34 --> E34
    
    C35 --> CH35
    CH35 --> R11
    CH35 --> E35
    
    C36 --> CH36
    CH36 --> R3
    CH36 --> R11
    CH36 --> E36
    
    C37 --> CH37
    CH37 --> R11
    CH37 --> E37
    CH37 -.-> E38

    %% Command flows - Venue Management
    C54 --> CH54
    CH54 --> R14
    CH54 --> E56

    C55 --> CH55
    CH55 --> R14
    CH55 --> E57

    C56 --> CH56
    CH56 --> R14
    CH56 --> E58

    C57 --> CH57
    CH57 --> R14
    CH57 --> E59

    C58 --> CH58
    CH58 --> R14
    CH58 --> E60

    C59 --> CH59
    CH59 --> R14
    CH59 --> E61

    C60 --> CH60
    CH60 --> R14
    CH60 --> E62

    C61 --> CH61
    CH61 --> R14
    CH61 --> E63

    %% Event triggers based on Policies from Event Storm
    %% P1
    E1 -.-> C2
    %% P2
    E2 -.-> C3
    %% P3
    E3 -.-> C4
    %% P4
    E4 -.-> C5
    %% P5
    E6 -.-> C11
    %% P6
    E3 -.-> C7
    %% P7
    E7 -.-> C8
    %% P8
    E2 -.-> C16
    %% P9
    E17 -.-> C4
    %% P10
    E1 -.-> C20
    %% P11
    E12 -.-> C20
    %% P12
    E1 -.-> C23
    %% P13, P16
    E24 -.-> C28
    E25 -.-> C28
    E26 -.-> C28
    %% P14
    E28 -.-> C29
    %% P15
    E27 -.-> C17
    %% P17
    E3 -.-> C37
    %% P18
    E17 -.-> C36
    %% P19
    E38 -.-> C5
    %% P20
    E7 -.-> C37
    %% P21
    E40 -.-> C41
    %% P22
    E12 -.-> C41
    %% P23
    E42 -.-> C42
    %% P24
    E3 -.-> C41
    %% P25
    E27 -.-> C43
    %% P26
    E28 -.-> C44
    %% P27
    E47 -.-> C46
    %% P28
    E8 -.-> C44
    %% P29
    E50 -.-> C49
    %% P30
    E51 -.-> C50
    %% P31
    E54 -.-> C53
    %% P32
    E53 -.-> C53

    %% Styles
    classDef command fill:#5D9CEC,stroke:#333,stroke-width:1px;
    classDef event fill:#FF9900,stroke:#333,stroke-width:1px;
    classDef handler fill:#4CAF50,stroke:#333,stroke-width:1px;
    classDef repository fill:#9C27B0,stroke:#333,stroke-width:1px,color:#fff;
    
    %% Apply styles to all nodes
    %% Event Planning
    class C1,C2,C23,C24,C25,C26,C27,C28 command;
    class E1,E2,E23,E24,E25,E26,E27,E28 event;
    class CH1,CH2,CH23,CH24,CH25,CH26,CH27,CH28 handler;
    
    %% Menu
    class C3,C17 command;
    class E3,E17,E45 event;
    class CH3,CH17 handler;
    
    %% Inventory
    class C4,C5,C6,C11,C29,C48,C49,C50,C51,C52,C53 command;
    class E4,E5,E6,E11,E29,E50,E51,E52,E53,E54,E55 event;
    class CH4,CH5,CH6,CH11,CH29,CH48,CH49,CH50,CH51,CH52,CH53 handler;
    
    %% Bar Setup
    class C7,C8,C9,C10 command;
    class E7,E8,E9,E10 event;
    class CH7,CH8,CH9,CH10 handler;
    
    %% Recipe
    class C12,C13,C14,C15,C16,C38,C39,C40,C41,C42,C43,C44,C45,C46,C47 command;
    class E12,E13,E14,E15,E16,E39,E40,E41,E42,E43,E44,E46,E47,E48,E49 event;
    class CH12,CH13,CH14,CH15,CH16,CH38,CH39,CH40,CH41,CH42,CH43,CH44,CH45,CH46,CH47 handler;
    
    %% Tagging System
    class C18,C19,C20,C21,C22 command;
    class E18,E19,E20,E21,E22 event;
    class CH18,CH19,CH20,CH21,CH22 handler;
    
    %% Equipment
    class C30,C31,C32,C33,C34,C35,C36,C37 command;
    class E30,E31,E32,E33,E34,E35,E36,E37,E38 event;
    class CH30,CH31,CH32,CH33,CH34,CH35,CH36,CH37 handler;
    
    %% Venue Management
    class C54,C55,C56,C57,C58,C59,C60,C61 command;
    class E56,E57,E58,E59,E60,E61,E62,E63 event;
    class CH54,CH55,CH56,CH57,CH58,CH59,CH60,CH61 handler;
    
    %% Repositories
    class R1,R2,R3,R4,R5,R6,R7,R8,R9,R10,R11,R12,R13,R14 repository;
    
    %% Legend
    subgraph Legend
        L1[/"Command"/]:::command
        L2{{Domain Event}}:::event
        L3[Command Handler]:::handler
        L4[(Repository)]:::repository
        L5-- Direct Flow -->L6
        L7-. Event Trigger .->L8
    end

Key Components

Command Handlers

Command handlers are responsible for processing commands and producing domain events. Each handler typically:

1. Validates the command
2. Retrieves data from repositories
3. Performs business logic
4. Persists changes to repositories
5. Generates domain events

Examples include:

• ScheduleEventHandler: Handles event creation
• CreateMenuHandler: Handles menu creation
• CheckInventoryHandler: Handles inventory checking
• AddBarHandler: Handles adding bars to venues
• UpdateBarHandler: Handles updating bar details
• RemoveBarHandler: Handles removing bars from venues

Commands

Commands are instructions to do something in the system. They are typically initiated by users or other parts of the system. Commands are named in the imperative tense:

• Schedule Event: Create a new event
• Check Inventory: Check current stock levels
• Add Recipe To Menu: Add a recipe to a menu
• Add Bar: Add a new bar to a venue
• Update Bar: Modify bar details and features
• Remove Bar: Remove a bar from a venue

Domain Events

Domain events represent something that has happened in the system. They are named in the past tense:

• EventScheduled: An event has been scheduled
• InventoryChecked: Inventory has been checked
• RecipeAddedToMenu: A recipe has been added to a menu
• BarAdded: A bar has been added to a venue
• BarUpdated: A bar’s details have been updated
• BarRemoved: A bar has been removed from a venue

Repositories

Repositories provide access to persistent storage for domain entities:

• EventRepository: Stores event data
• MenuRepository: Stores menu data
• InventoryRepository: Stores inventory data
• RecipeRepository: Stores recipe data
• VenueRepository: Stores venue data including bars and storage areas

Event Triggers

Event triggers (shown as dotted lines) represent event-driven behavior where an event triggers a new command:

• EventScheduled triggers Define Event Theme
• ThemeDefined triggers Create Menu
• MenuCreated triggers Check Inventory

Main Workflows

The Command Flow diagram shows several key workflows:

Event Planning Workflow

1. Schedule Event command is processed by ScheduleEventHandler
2. EventScheduled event is generated
3. This triggers the Define Event Theme command
4. DefineEventThemeHandler processes the command
5. ThemeDefined event is generated
6. This triggers the Create Menu command

Inventory Management Workflow

1. MenuCreated event triggers Check Inventory command
2. CheckInventoryHandler processes the command
3. InventoryChecked event is generated
4. This triggers Generate Shopping List command
5. ShoppingListGenerated event is produced
6. When supplies are purchased, Update Inventory is triggered

Recipe Management Workflow

1. Create Recipe command is processed by CreateRecipeHandler
2. RecipeCreated event is generated
3. This triggers Calculate Recipe Balance command
4. RecipeBalanceCalculated event is generated
5. If the recipe is unbalanced, it triggers Suggest Balancing Ingredients

Bar Management Workflow

1. Add Bar command is processed by AddBarHandler
2. AddBarHandler validates the bar data and venue existence
3. AddBarHandler persists the new bar to VenueRepository
4. BarAdded event is generated
5. Update Bar and Remove Bar commands follow similar patterns through their respective handlers
6. All bar management operations are scoped within the Venue Aggregate boundary

Benefits of Command Flow Modeling

The Command Flow diagram provides several benefits:

1. Clear Implementation Path: Provides a clear path for implementing the system
2. Separation of Concerns: Clearly separates commands, events, and repositories
3. Event-Driven Architecture: Shows how events trigger subsequent commands
4. Traceability: Makes it easy to trace how a user action flows through the system
5. Testability: Each command handler can be tested in isolation

This diagram complements the Event Storming and Domain Model diagrams by focusing more on the implementation details of the system’s architecture, particularly the command handling and event generation mechanisms.