API - Application Programming Interface

APIs - Application Programming Interface

APIs are used for Communications

Abstraction hiding the implementation of process , ex if you hit the POST call its will go to the Server and its post the data but actually the POST doesn’t know the How its implementing in Server

Platform Agnostic – Service are written in the Different language and different platform can easily Communicate with each other using APIs

Examples / Use Cases of APIs

Private APIs – Hidden APIs that only an Applications running on your Device or Phone its access to not for public use Ex : Payment Apps

Public APIs - Its available for public Ex : Google Map

Web APIs – Super set of Public & Private APIs , The Application which running on Cloud can Interact with each other using Web APIs Ex : Instagram Post

SDK / Library APIs – Threating Library which expose the function like Lock , Release , Fork , Join we can use this APIs

API Factors :

API Contracts

Documentation

Data format

Security

API Standards

RPC

SOAP

REST

Here’s a comparison between RPC , SOAP , and REST APIs:

1. RPC (Remote Procedure Call)

• Concept : RPC allows a program to execute procedures (methods or functions) on a remote server as if they were local calls. The server and client communicate using a specified protocol.

• Protocol : Can use various protocols (e.g., HTTP, XML-RPC, JSON-RPC).

• Message Format : Typically uses lightweight message formats like JSON or XML.

• Usage : It is ideal for scenarios where you need direct method/function calls across different systems.

• Pros :

  • Easy to understand and implement.

  • Suitable for microservices that need to expose simple function-based interactions.

• Cons :

  • Tight coupling between client and server.

  • Less flexibility than REST.

  2. SOAP (Simple Object Access Protocol)

• Concept : SOAP is a protocol for exchanging structured information in web services. It uses XML to format the data and operates over various application layer protocols like HTTP, SMTP.

• Protocol : Follows strict rules and standards (such as WS-Security, WS-AtomicTransaction, etc.).

• Message Format : XML-based message structure.

• Usage : Preferred in enterprise-level applications where security, ACID transactions, or complex operations are crucial (e.g., financial systems).

• Pros :

  • Built-in standards for security, transactions, etc.

  • Works well with stateful operations.

• Cons :

  • Heavyweight due to the extensive use of XML.

  • Slower performance compared to REST because of overhead.

  3. REST (Representational State Transfer)

• Concept : REST is an architectural style that uses standard HTTP methods (GET, POST, PUT, DELETE) for interacting with resources represented by URLs.

• Protocol : Uses HTTP/HTTPS for communication.

• Message Format : Flexible, often uses JSON or XML for data representation.

• Usage : Widely used for web services due to its simplicity and scalability (e.g., CRUD operations).

• Pros :

  • Lightweight and stateless.

  • Flexible and scalable.

  • Better performance than SOAP in most cases.

• Cons :

  • No built-in standards for security and transactions (can be added separately).

  • May not be suitable for highly complex interactions.

Key Differences:

Each has its strengths, depending on the use case (e.g., SOAP for secure enterprise systems, REST for scalable web services, RPC for simple function calls).