REST API
REST API stands for Representational State Transfer Application Programming Interface. It is an architectural style, not a protocol or standard, which was introduced and defined in 2000 by Roy Fielding in his doctoral dissertation. This style is designed to take advantage of the existing protocols of the web, particularly HTTP.
Key Principles
- Stateless: Each request from a client to server must contain all of the information necessary to understand and process the request. The server should not store any client context between requests.
- Client-Server: The architecture must be separated into clients and servers where clients are not concerned with data storage, which remains internal to each server, and servers do not need to be concerned with the user interface or user state.
- Cacheable: Responses from the server must explicitly or implicitly define themselves as cacheable or not to prevent clients from reusing stale or inappropriate data in response to further requests.
- Layered System: A client cannot ordinarily tell whether it's connected directly to the end server, or an intermediary along the way. This allows for load balancing, shared caches, or security policies to be implemented in layers.
- Uniform Interface: The key to making the design simple is having a uniform interface. This simplifies and decouples the architecture, which enables each part to evolve independently.
- Code on Demand (optional): Servers can provide executable code to clients, like applets or scripts, allowing for dynamic functionality.
History and Context
The concept of REST was developed in response to the limitations of older web service protocols like SOAP. REST was designed to be more scalable, simple, and efficient for the web, leveraging HTTP methods directly for CRUD operations (Create, Read, Update, Delete) rather than inventing new protocols. It fits well with the architectural constraints of the web, making it an ideal choice for many web services.
Usage
REST APIs are widely used for:
- Web Services: Many web services, especially those requiring scalability and performance, use RESTful principles.
- Mobile Applications: REST APIs are commonly used for mobile app backends due to their stateless nature, which reduces server load and simplifies scaling.
- Internet of Things (IoT): RESTful services are often used in IoT for device-to-device communication where bandwidth and processing power might be limited.
Advantages
- Scalability: Due to its stateless nature, REST allows services to scale more easily.
- Performance: Caching can improve performance by reducing server load.
- Flexibility: Supports different types of data formats like JSON, XML, HTML, etc.
- Interoperability: Because it uses standard HTTP methods, it works well with existing web infrastructure.
Limitations
- Complexity in Large Applications: While REST simplifies many things, complex applications might require a lot of endpoints which can become unwieldy.
- Lack of Standards: There is no strict standard for REST, which can lead to inconsistent implementations.
- Overfetching/Underfetching: REST might retrieve more or less data than needed, which isn't as efficient as some alternatives like GraphQL.
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