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Fusioncat is currently in its alpha stage. The main API server is located at: https://api.staging.fusioncatalyst.io/Please note that breaking changes and bugs are to be expected, as the product is still under active development.

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Message Management Commands

The paw messages commands allow you to create and manage messages that are based on your schema definitions.

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Commands

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messages list

List all messages in a project. 
paw messages list --project-id <id>

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Options

  • --project-id (required): The ID of the project

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Examples

# List all messages
paw messages list --project-id "project-uuid"

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messages new

Create a new message based on a schema. 
paw messages new --project-id <id> --name <name> --schema-id <id> --schema-version <version> [--description <description>]

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Options

  • --project-id (required): The ID of the project
  • --name (required): Name of the message
  • --schema-id (required): The ID of the schema this message is based on
  • --schema-version (required): The version of the schema to use
  • --description: Description of the message

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Examples

# Create a message
paw messages new --project-id "project-uuid" --name "UserCreatedEvent" --schema-id "user-schema-uuid" --schema-version "v1.0.0"

# Create with description
paw messages new --project-id "project-uuid" --name "OrderShippedNotification" --schema-id "order-schema-uuid" --schema-version "v2.1.0" --description "Sent when order ships"

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Understanding Messages

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What is a Message?

A message is a concrete implementation of a schema used for:
  • Event definitions in event-driven architectures
  • API request/response definitions
  • Data transfer objects (DTOs)
  • Queue message formats

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Message vs Schema

  • Schema: The abstract data structure definition
  • Message: A specific use case of that schema
Example:
  • Schema: User (defines user data structure)
  • Messages: UserCreatedEvent, UserUpdatedEvent, UserProfileResponse

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Message Versioning

Messages are tied to specific schema versions:
  • When a schema updates, existing messages continue using their version
  • Create new messages for new schema versions
  • Allows gradual migration

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Event-Driven Architecture

Messages are particularly useful for event-driven systems: 
# Create event schemas
paw schemas new --project-id "project-uuid" --name "OrderEvent" --type jsonschema --schema-file ./order-event.json

# Create specific event messages
paw messages new --project-id "project-uuid" --name "OrderCreated" --schema-id "order-event-uuid" --schema-version "v1.0.0"
paw messages new --project-id "project-uuid" --name "OrderShipped" --schema-id "order-event-uuid" --schema-version "v1.0.0"
paw messages new --project-id "project-uuid" --name "OrderDelivered" --schema-id "order-event-uuid" --schema-version "v1.0.0"
paw messages new --project-id "project-uuid" --name "OrderCancelled" --schema-id "order-event-uuid" --schema-version "v1.0.0"

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Best Practices

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Naming Conventions

  1. Events: Use past tense - UserCreated, OrderShipped
  2. Commands: Use imperative - CreateUser, ShipOrder
  3. Requests/Responses: Be descriptive - GetUserRequest, UserProfileResponse

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Message Organization

Group related messages: 
User Domain:
- UserCreatedEvent
- UserUpdatedEvent
- UserDeletedEvent
- GetUserRequest
- UserResponse

Order Domain:
- OrderPlacedEvent
- OrderShippedEvent
- OrderDeliveredEvent
- CreateOrderCommand
- OrderStatusResponse

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Schema Reuse

Multiple messages can use the same schema: 
# One schema, multiple messages
paw messages new --project-id "pid" --name "CreateUserRequest" --schema-id "user-schema" --schema-version "v1"
paw messages new --project-id "pid" --name "UpdateUserRequest" --schema-id "user-schema" --schema-version "v1"
paw messages new --project-id "pid" --name "UserResponse" --schema-id "user-schema" --schema-version "v1"

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Examples

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API Message Definitions

# Request/Response pairs
paw messages new --project-id "project-uuid" \
  --name "CreateProductRequest" \
  --schema-id "product-schema-uuid" \
  --schema-version "v1.0.0" \
  --description "API request to create a new product"

paw messages new --project-id "project-uuid" \
  --name "ProductResponse" \
  --schema-id "product-schema-uuid" \
  --schema-version "v1.0.0" \
  --description "API response containing product data"

paw messages new --project-id "project-uuid" \
  --name "ProductListResponse" \
  --schema-id "product-list-schema-uuid" \
  --schema-version "v1.0.0" \
  --description "API response for product listings"

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Event Sourcing

# Define events for an aggregate
paw messages new --project-id "project-uuid" --name "AccountOpened" --schema-id "account-event-uuid" --schema-version "v1"
paw messages new --project-id "project-uuid" --name "MoneyDeposited" --schema-id "transaction-event-uuid" --schema-version "v1"
paw messages new --project-id "project-uuid" --name "MoneyWithdrawn" --schema-id "transaction-event-uuid" --schema-version "v1"
paw messages new --project-id "project-uuid" --name "AccountClosed" --schema-id "account-event-uuid" --schema-version "v1"

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Microservices Communication

# Service A publishes
paw messages new --project-id "project-uuid" \
  --name "InventoryUpdatedEvent" \
  --schema-id "inventory-schema-uuid" \
  --schema-version "v2.0.0"

# Service B consumes and publishes
paw messages new --project-id "project-uuid" \
  --name "PriceRecalculationCommand" \
  --schema-id "pricing-command-uuid" \
  --schema-version "v1.0.0"

# Service C responds
paw messages new --project-id "project-uuid" \
  --name "PriceUpdatedEvent" \
  --schema-id "price-event-uuid" \
  --schema-version "v1.0.0"

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Working with Servers and Resources

Messages are often used with servers and resources: 
# Create a Kafka server
paw servers new --project-id "project-uuid" --name "Event Bus" --type "async+kafka" --description "Main event bus"

# Create topics for messages
paw resources new --server-id "server-uuid" --name "user-events" --type topic --mode write
paw resources new --server-id "server-uuid" --name "order-events" --type topic --mode readwrite

# Messages can now be published to these topics