Introduction to REST APIs
REST APIs form the backbone of modern enterprise integrations. In Oracle Fusion,
REST APIs are widely used to exchange data securely and efficiently between systems
such as Oracle Integration Cloud (OIC), Visual Builder Cloud Service (VBCS),
and external applications.
1. The Foundation: HTTP vs HTTPS
REST APIs rely on the HTTP protocol to transfer data between a client and a server.
Understanding the difference between HTTP and HTTPS is essential before working
with APIs in production environments.
-
HTTP (Hypertext Transfer Protocol):
Transfers data in clear text. Any data sent over HTTP can be read if intercepted,
making it unsuitable for sensitive information. -
HTTPS:
Adds a security layer using TLS/SSL encryption. Data is encrypted between the
client and server, ensuring confidentiality and integrity.
Although developers often say “HTTP” in general discussions, all production REST APIs,
including Oracle Fusion REST APIs, must use HTTPS.
2. Client Server Model
All REST APIs follow the client server architecture.
-
Client:
The consumer of the API, such as a browser, Postman, OIC integration, or VBCS application. -
Server:
The system hosting the API and business logic, such as Oracle Fusion Applications.
The client sends a request, the server processes it, and a response is returned.
This request response lifecycle is the foundation of all REST based communication.
3. HTTP Methods (Action Verbs)
HTTP methods define the action to be performed on a resource.
Commonly Used Methods
- GET: Retrieve data
- POST: Create new data
- PUT: Replace an existing resource
- PATCH: Partially update a resource
- DELETE: Remove a resource
Less Used but Important Methods
- HEAD: Retrieve only response headers
- OPTIONS: Discover supported operations for a resource
4. HTTP Headers
Headers are key value pairs that provide metadata about a request or response.
They do not carry business data but control how the request is handled.
Common Headers
- Accept: Defines the response format, for example application/json
- Content-Type: Specifies the request payload format
- Authorization: Sends credentials such as tokens
- User-Agent: Identifies the client application
5. HTTP Status Codes
Status codes communicate the outcome of an API request.
- 1xx: Informational responses
- 2xx: Successful responses (200 OK, 201 Created, 204 No Content)
- 3xx: Redirection responses
- 4xx: Client errors (400 Bad Request, 401 Unauthorized, 404 Not Found)
- 5xx: Server errors (500 Internal Server Error)
6. API Authentication
Basic Authentication
Uses a username and password encoded in Base64 and sent with every request.
It is simple but not recommended for modern production systems without HTTPS.
API Key Authentication
A unique key is sent in the request header or query parameter.
API keys are typically long lived and used for basic access control.
Bearer Token and JWT
Bearer tokens are commonly implemented using JWT.
The token is issued by an authentication service and sent in the Authorization header.
OAuth 2.0
OAuth 2.0 is a secure authorization framework used extensively in Oracle Fusion.
It uses access tokens and refresh tokens and supports flows such as Authorization Code Grant.
Postman can automate the OAuth flow for testing APIs.
7. REST API Design Best Practices
- Use resource based URLs and meaningful hierarchy
- Keep URIs lowercase and consistent
- Use correct HTTP methods for each operation
- Ensure APIs are stateless
- Implement proper API versioning
8. Security Best Practices
- Always use HTTPS
- Implement strong authentication and authorization
- Use role based access control
- Validate and sanitize inputs
- Apply security headers
9. Performance and Scalability
Rate Limiting
Rate limiting protects APIs from abuse using strategies such as fixed window,
sliding window, and token bucket.
Monitoring and Logging
Monitoring tools and structured logging improve observability and troubleshooting.
10. REST API Caching
Application Layer Caching
Uses in memory stores such as Redis or Memcached to reduce database calls.
Request Level Caching
Caches entire GET responses using cache keys derived from request parameters.
Conditional Caching
Uses ETag and Last Modified headers to avoid sending unchanged data.
11. Fusion REST API Concepts
Oracle Fusion REST APIs provide advanced query parameters such as q,
pagination, sorting, finder, expand, fields, and onlyData options.
These features allow efficient data retrieval and optimized integrations.
Conclusion
Understanding REST API fundamentals is essential before working with Oracle Fusion
integrations. Mastering HTTP concepts, authentication, security, and performance
best practices ensures scalable and reliable enterprise integrations.