PetstoreAPI RAML Protocol Guide

Overview

RAML Specification: https://api.petstoreapi.com/v1/specs/modern-petstore.raml Protocol: RESTful API over HTTP/HTTPS RAML Version: RAML 1.0 Format: YAML-based API description language RAML is a YAML-based language for describing RESTful APIs. It provides a structured, human-readable format for API design that emphasizes reusability, modularity, and developer experience.

What is RAML?

RAML (RESTful API Modeling Language) is a YAML-based language specifically designed for describing RESTful APIs. It focuses on making API design simple, reusable, and human-readable while providing powerful features for complex API specifications.

Key Features

✅ Human-Readable: YAML syntax is clean and intuitive
✅ Reusable Components: Types, traits, and resource types
✅ Design-First: Facilitates API-first development
✅ Documentation: Auto-generates interactive documentation
✅ Code Generation: Generates server stubs and client SDKs
✅ Validation: Strong typing with built-in validation
✅ Modular: Split specifications across multiple files

When to Use RAML

RAML is particularly useful when:

Designing APIs before implementation (design-first approach)
Need highly modular, reusable API specifications
Working with MuleSoft or other RAML-first tools
Requiring strong type validation
Building APIs with consistent patterns
Collaborating with API designers and developers

RAML Structure

A RAML specification consists of these main sections:

#%RAML 1.0
title: Modern Petstore API
version: v1
baseUri: https://api.petstoreapi.com/{version}
protocols: [HTTPS]
mediaType: application/json

documentation:
  - title: Introduction
    content: |
      Modern Petstore API demonstrating RESTful best practices
      and OpenAPI 3.2 features.

# Types (Data Models)
types:
  Pet:
    type: object
    properties:
      id:
        type: string
        description: Unique identifier
      name:
        type: string
        description: Pet name
        minLength: 1
        maxLength: 100
      species:
        type: string
        enum: [DOG, CAT, RABBIT, BIRD, REPTILE, OTHER]

# Traits (Reusable Behaviors)
traits:
  paginated:
    queryParameters:
      page:
        type: integer
        default: 1
        minimum: 1
      limit:
        type: integer
        default: 20
        minimum: 1
        maximum: 100

  searchable:
    queryParameters:
      q:
        type: string
        required: false
        description: Search query

# Resource Types (Reusable Resources)
resourceTypes:
  collection:
    get:
      description: List all <<resourcePathName>>
      responses:
        200:
          body:
            application/json:
              type: <<resourcePathName | !uppercamelcase>>Collection
    post:
      description: Create a new <<resourcePathName | !singularize>>
      body:
        application/json:
          type: <<resourcePathName | !uppercamelcase | !singularize>>
      responses:
        201:
          body:
            application/json:
              type: <<resourcePathName | !uppercamelcase | !singularize>>

# API Resources
/pets:
  type: collection
  is: [paginated, searchable]
  get:
    queryParameters:
      species:
        type: string
        enum: [DOG, CAT, RABBIT, BIRD, REPTILE, OTHER]
      status:
        type: string
        enum: [AVAILABLE, PENDING, ADOPTED, NOT_AVAILABLE]
        default: AVAILABLE

  /{id}:
    uriParameters:
      id:
        type: string
        description: Unique pet identifier
    get:
      description: Get a specific pet
      responses:
        200:
          body:
            application/json:
              type: Pet
        404:
          body:
            application/json:
              type: Error

Understanding RAML Elements

Types (Data Models)

RAML uses types to define data structures:

types:
  # Object type
  Pet:
    type: object
    properties:
      id:
        type: string
        pattern: ^pet_[a-zA-Z0-9]+$
      name:
        type: string
        minLength: 1
        maxLength: 100
      species:
        type: PetSpecies
      ageMonths:
        type: integer
        minimum: 0
      status:
        type: PetStatus
      adoptionFee?:  # Optional property (?)
        type: number
        minimum: 0
    required: [id, name, species, ageMonths, status]

  # Enum type
  PetSpecies:
    type: string
    enum:
      - DOG
      - CAT
      - RABBIT
      - BIRD
      - REPTILE
      - OTHER

  # Enum type
  PetStatus:
    type: string
    enum: [AVAILABLE, PENDING, ADOPTED, NOT_AVAILABLE]

  # Array type
  PetArray:
    type: Pet[]

  # Collection wrapper
  PetCollection:
    type: object
    properties:
      data:
        type: Pet[]
      pagination:
        type: PaginationMetadata
      links:
        type: NavigationLinks

  # Nested type
  PaginationMetadata:
    type: object
    properties:
      page:
        type: integer
      limit:
        type: integer
      totalItems:
        type: integer
      totalPages:
        type: integer

  # Union type (polymorphism)
  PaymentSource:
    type: CardPaymentSource | BankAccountPaymentSource
    discriminator: object

  CardPaymentSource:
    type: object
    discriminatorValue: CARD
    properties:
      object:
        type: string
        enum: [CARD]
      cardNumber:
        type: string
        pattern: ^\d{13,19}$

  BankAccountPaymentSource:
    type: object
    discriminatorValue: BANK_ACCOUNT
    properties:
      object:
        type: string
        enum: [BANK_ACCOUNT]
      accountNumber:
        type: string

Traits (Reusable Behaviors)

Traits are reusable method characteristics:

traits:
  # Pagination trait
  paginated:
    queryParameters:
      page:
        type: integer
        default: 1
        minimum: 1
        description: Page number
      limit:
        type: integer
        default: 20
        minimum: 1
        maximum: 100
        description: Items per page

  # Search trait
  searchable:
    queryParameters:
      q:
        type: string
        required: false
        description: Search query

  # Authentication trait
  authenticated:
    headers:
      Authorization:
        type: string
        pattern: ^Bearer .+$
        description: Bearer token
        example: Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9...

  # Rate limiting trait
  rateLimited:
    responses:
      429:
        description: Rate limit exceeded
        headers:
          RateLimit-Limit:
            type: integer
            description: Request limit per window
          RateLimit-Remaining:
            type: integer
            description: Remaining requests
          RateLimit-Reset:
            type: integer
            description: Reset timestamp (Unix time)

# Apply traits to resources
/pets:
  get:
    is: [paginated, searchable, rateLimited]
  post:
    is: [authenticated, rateLimited]

Resource Types (Reusable Resources)

Resource types define reusable resource patterns:

resourceTypes:
  # Standard collection pattern
  collection:
    description: Collection of <<resourcePathName>>
    get:
      description: List all <<resourcePathName>>
      is: [paginated]
      responses:
        200:
          body:
            application/json:
              type: <<resourcePathName | !uppercamelcase>>Collection
    post:
      description: Create a new <<resourcePathName | !singularize>>
      is: [authenticated]
      body:
        application/json:
          type: <<resourcePathName | !uppercamelcase | !singularize>>
      responses:
        201:
          description: Created successfully
          headers:
            Location:
              description: URL of created resource
          body:
            application/json:
              type: <<resourcePathName | !uppercamelcase | !singularize>>

  # Standard member pattern
  member:
    description: Single <<resourcePathName | !singularize>>
    get:
      description: Get <<resourcePathName | !singularize>>
      responses:
        200:
          body:
            application/json:
              type: <<resourcePathName | !uppercamelcase | !singularize>>
        404:
          body:
            application/json:
              type: Error
    put:
      description: Update <<resourcePathName | !singularize>>
      is: [authenticated]
      body:
        application/json:
          type: <<resourcePathName | !uppercamelcase | !singularize>>
      responses:
        200:
          body:
            application/json:
              type: <<resourcePathName | !uppercamelcase | !singularize>>
    delete:
      description: Delete <<resourcePathName | !singularize>>
      is: [authenticated]
      responses:
        204:
          description: Deleted successfully

# Apply resource types
/pets:
  type: collection
  /{id}:
    type: member

/users:
  type: collection
  /{id}:
    type: member

/orders:
  type: collection
  /{id}:
    type: member

Code Examples

TypeScript

import axios from 'axios';

const baseURL = 'https://api.petstoreapi.com/v1';

// List pets with filtering and pagination
async function listPets() {
  const response = await axios.get(`${baseURL}/pets`, {
    params: {
      species: 'DOG',
      status: 'AVAILABLE',
      page: 1,
      limit: 20
    }
  });

  const { data, pagination } = response.data;
  console.log(`Found ${pagination.totalItems} pets`);
  return data;
}

// Get a specific pet
async function getPet(id: string) {
  const response = await axios.get(`${baseURL}/pets/${id}`);
  return response.data;
}

// Create a new pet
async function createPet(token: string) {
  const response = await axios.post(
    `${baseURL}/pets`,
    {
      name: 'Buddy',
      species: 'DOG',
      breed: 'Golden Retriever',
      ageMonths: 24,
      status: 'AVAILABLE',
      adoptionFee: 150.00,
      currency: 'USD'
    },
    {
      headers: {
        'Authorization': `Bearer ${token}`,
        'Content-Type': 'application/json'
      }
    }
  );

  console.log(`Created pet: ${response.data.id}`);
  return response.data;
}

// Update a pet
async function updatePet(id: string, token: string) {
  const response = await axios.put(
    `${baseURL}/pets/${id}`,
    {
      name: 'Buddy',
      species: 'DOG',
      ageMonths: 25,
      status: 'ADOPTED'
    },
    {
      headers: {
        'Authorization': `Bearer ${token}`
      }
    }
  );

  return response.data;
}

// Delete a pet
async function deletePet(id: string, token: string) {
  await axios.delete(`${baseURL}/pets/${id}`, {
    headers: {
      'Authorization': `Bearer ${token}`
    }
  });

  console.log('Pet deleted successfully');
}

Python

import requests

BASE_URL = 'https://api.petstoreapi.com/v1'

# List pets with filtering
def list_pets():
    response = requests.get(f'{BASE_URL}/pets', params={
        'species': 'DOG',
        'status': 'AVAILABLE',
        'page': 1,
        'limit': 20
    })

    data = response.json()
    print(f"Found {data['pagination']['totalItems']} pets")
    return data['data']

# Get a specific pet
def get_pet(pet_id):
    response = requests.get(f'{BASE_URL}/pets/{pet_id}')
    response.raise_for_status()
    return response.json()

# Create a new pet
def create_pet(token):
    response = requests.post(
        f'{BASE_URL}/pets',
        json={
            'name': 'Buddy',
            'species': 'DOG',
            'breed': 'Golden Retriever',
            'ageMonths': 24,
            'status': 'AVAILABLE',
            'adoptionFee': 150.00,
            'currency': 'USD'
        },
        headers={
            'Authorization': f'Bearer {token}',
            'Content-Type': 'application/json'
        }
    )

    response.raise_for_status()
    pet = response.json()
    print(f"Created pet: {pet['id']}")
    return pet

# Handle errors with RAML-defined error format
try:
    pet = get_pet('invalid_id')
except requests.HTTPError as e:
    if e.response.status_code == 404:
        error = e.response.json()
        print(f"Error: {error['title']} - {error['detail']}")

cURL

# List pets with filtering
curl "https://api.petstoreapi.com/v1/pets?species=DOG&status=AVAILABLE&page=1&limit=20"

# Get a specific pet
curl https://api.petstoreapi.com/v1/pets/pet_fYrZzCW9E1WIOyGw

# Create a new pet (requires authentication)
curl -X POST https://api.petstoreapi.com/v1/pets \
  -H "Authorization: Bearer YOUR_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "name": "Buddy",
    "species": "DOG",
    "breed": "Golden Retriever",
    "ageMonths": 24,
    "status": "AVAILABLE",
    "adoptionFee": 150.00,
    "currency": "USD"
  }'

# Update a pet
curl -X PUT https://api.petstoreapi.com/v1/pets/pet_fYrZzCW9E1WIOyGw \
  -H "Authorization: Bearer YOUR_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{
    "name": "Buddy",
    "species": "DOG",
    "ageMonths": 25,
    "status": "ADOPTED"
  }'

# Delete a pet
curl -X DELETE https://api.petstoreapi.com/v1/pets/pet_fYrZzCW9E1WIOyGw \
  -H "Authorization: Bearer YOUR_TOKEN"

RAML Tools

API Console

Interactive API documentation:

# Install RAML API Console
npm install -g api-console-cli

# Serve API Console
api-console dev https://api.petstoreapi.com/v1/specs/modern-petstore.raml

# Opens at http://localhost:8080

Code Generation

Generate Node.js Server (Osprey)

# Install Osprey
npm install -g osprey-cli

# Generate Express.js server
osprey-gen --language node https://api.petstoreapi.com/v1/specs/modern-petstore.raml ./server

cd server
npm install
npm start

Generate Client SDK (raml-client-generator)

# Install generator
npm install -g raml-client-generator

# Generate TypeScript client
raml-client-generator https://api.petstoreapi.com/v1/specs/modern-petstore.raml \
  --language typescript \
  --output ./client

Validation

Validate RAML Specification

# Install RAML parser
npm install -g raml-1-parser

# Validate RAML
raml-validate petstore.raml

# Parse and display structure
raml-parse petstore.raml

Design Patterns

1. Modular Specifications

Split large RAML files into modules: main.raml:

#%RAML 1.0
title: Petstore API
version: v1

uses:
  types: ./types.raml
  traits: ./traits.raml

/pets:
  type: types.collection
  is: [traits.paginated]

types.raml:

#%RAML 1.0 Library

types:
  Pet:
    type: object
    properties:
      id: string
      name: string

  collection:
    get:
      responses:
        200:
          body:
            application/json

traits.raml:

#%RAML 1.0 Library

traits:
  paginated:
    queryParameters:
      page:
        type: integer
        default: 1

2. Overlays

Extend RAML specifications without modifying the original: base.raml:

#%RAML 1.0
title: Petstore API

/pets:
  get:
    description: List pets

overlay.raml:

#%RAML 1.0 Overlay
extends: base.raml

/pets:
  get:
    queryParameters:
      species:
        type: string
        enum: [DOG, CAT]

3. Examples

Include realistic examples:

types:
  Pet:
    type: object
    properties:
      id: string
      name: string
      species: string
    example:
      id: pet_fYrZzCW9E1WIOyGw
      name: Buddy
      species: DOG

/pets:
  get:
    responses:
      200:
        body:
          application/json:
            type: PetCollection
            example:
              data:
                - id: pet_fYrZzCW9E1WIOyGw
                  name: Buddy
                  species: DOG
                - id: pet_abc123
                  name: Whiskers
                  species: CAT
              pagination:
                page: 1
                limit: 20
                totalItems: 2
                totalPages: 1

RAML vs OpenAPI

Feature	RAML	OpenAPI
Format	YAML only	YAML or JSON
Reusability	Excellent (traits, types, resource types)	Good (components)
Modularity	Libraries, overlays, fragments	$ref (external files)
Learning Curve	Moderate	Easier
Tooling	MuleSoft-focused	Broader ecosystem
Type System	Built-in types	JSON Schema
Design Patterns	Resource types, traits	Components, schemas
Community	Smaller	Larger (OpenAPI Initiative)
Use Case	API design, MuleSoft	API documentation, tooling

When to Use RAML

✅ Choose RAML when:

Using MuleSoft Anypoint Platform
Need highly modular specifications
Want design-first approach with strong patterns
Require reusable resource types and traits
Building APIs with consistent patterns
Team prefers YAML

When to Use OpenAPI

✅ Choose OpenAPI when:

Need broad tooling support
Want industry-standard format
Building APIs for multiple platforms
Using Swagger/Redoc documentation
Integrating with API gateways
Want JSON Schema compatibility

Best Practices

1. Use Descriptive Resource Names

✅ GOOD:
/pets              # Plural, descriptive
/orders            # Clear purpose
/users             # Standard naming

❌ BAD:
/pet               # Singular
/get-pets          # Verb in URL
/p                 # Too short

2. Leverage Resource Types

resourceTypes:
  collection:
    get:
      is: [paginated]
    post:
      is: [authenticated]

# Apply to multiple resources
/pets: { type: collection }
/users: { type: collection }
/orders: { type: collection }

3. Use Traits for Cross-Cutting Concerns

traits:
  authenticated: ...
  paginated: ...
  searchable: ...
  rateLimited: ...

/pets:
  get:
    is: [paginated, searchable, rateLimited]
  post:
    is: [authenticated, rateLimited]

4. Document with Examples

/pets/{id}:
  get:
    description: Retrieve pet details
    responses:
      200:
        body:
          application/json:
            type: Pet
            example:
              id: pet_fYrZzCW9E1WIOyGw
              name: Buddy
              species: DOG
              ageMonths: 24
              status: AVAILABLE

Migration Guide

From RAML to OpenAPI

Convert RAML specifications to OpenAPI:

# Install oas-raml-converter
npm install -g oas-raml-converter

# Convert RAML to OpenAPI 3.0
oas-raml-converter --from RAML --to OAS30 petstore.raml > petstore-openapi.yaml

Manual Mapping:

RAML	OpenAPI 3.x
Types	Components/Schemas
Traits	Reusable parameters/responses
Resource Types	Path item templates
Security Schemes	Security Schemes
Examples	Examples

From OpenAPI to RAML

Our conversion script generates RAML from OpenAPI:

npm run oas30-to-raml

Additional Resources

RAML Specification: https://api.petstoreapi.com/v1/specs/modern-petstore.raml
RAML 1.0 Spec: https://github.com/raml-org/raml-spec/blob/master/versions/raml-10/raml-10.md
RAML Official Site: https://raml.org
MuleSoft Documentation: https://docs.mulesoft.com/
Related Protocols:

Support

For questions or issues with the RAML specification:

GitHub Issues: https://github.com/petstoreapi/PetstoreAPI/issues
Documentation: https://docs.petstoreapi.com
API Reference: https://docs.petstoreapi.com

Getting Started

Protocol Guides

Overview

What is RAML?

Key Features

When to Use RAML

RAML Structure

Understanding RAML Elements

Types (Data Models)

Traits (Reusable Behaviors)

Resource Types (Reusable Resources)

Code Examples

TypeScript

Python

cURL

RAML Tools

API Console

Code Generation

Generate Node.js Server (Osprey)

Generate Client SDK (raml-client-generator)

Validation

Validate RAML Specification

Design Patterns

1. Modular Specifications

2. Overlays

3. Examples

RAML vs OpenAPI

When to Use RAML

When to Use OpenAPI

Best Practices

1. Use Descriptive Resource Names

2. Leverage Resource Types

3. Use Traits for Cross-Cutting Concerns

4. Document with Examples

Migration Guide

From RAML to OpenAPI

From OpenAPI to RAML

Additional Resources

Support

Getting Started

Protocol Guides

​Overview

​What is RAML?

​Key Features

​When to Use RAML

​RAML Structure

​Understanding RAML Elements

​Types (Data Models)

​Traits (Reusable Behaviors)

​Resource Types (Reusable Resources)

​Code Examples

​TypeScript

​Python

​cURL

​RAML Tools

​API Console

​Code Generation

​Generate Node.js Server (Osprey)

​Generate Client SDK (raml-client-generator)

​Validation

​Validate RAML Specification

​Design Patterns

​1. Modular Specifications

​2. Overlays

​3. Examples

​RAML vs OpenAPI

​When to Use RAML

​When to Use OpenAPI

​Best Practices

​1. Use Descriptive Resource Names

​2. Leverage Resource Types

​3. Use Traits for Cross-Cutting Concerns

​4. Document with Examples

​Migration Guide

​From RAML to OpenAPI

​From OpenAPI to RAML

​Additional Resources

​Support

Overview

What is RAML?

Key Features

When to Use RAML

RAML Structure

Understanding RAML Elements

Types (Data Models)

Traits (Reusable Behaviors)

Resource Types (Reusable Resources)

Code Examples

TypeScript

Python

cURL

RAML Tools

API Console

Code Generation

Generate Node.js Server (Osprey)

Generate Client SDK (raml-client-generator)

Validation

Validate RAML Specification

Design Patterns

1. Modular Specifications

2. Overlays

3. Examples

RAML vs OpenAPI

When to Use RAML

When to Use OpenAPI

Best Practices

1. Use Descriptive Resource Names

2. Leverage Resource Types

3. Use Traits for Cross-Cutting Concerns

4. Document with Examples

Migration Guide

From RAML to OpenAPI

From OpenAPI to RAML

Additional Resources

Support