What is an API? Understanding the API Lifecycle

Today, we all expect information to be immediately available, right at our fingertips, whenever we want it. Application programming interfaces (APIs) make that kind of instant connectivity possible. APIs are crucial building blocks of programming code that allow an app or service to communicate with other digital products and services. The code in the API allows data to be transmitted from one piece of software to another.

Developers save time and money using APIs. They can use these pre-designed blocks of code rather than having to do all the coding themselves, from scratch. APIs provide developers with greater flexibility and allow for simplified designs while also creating a wealth of opportunities for innovation.

What is an API?

An API (Application Programming Interface) is a set of rules and protocols that allows different software applications to communicate with each other. It acts as an intermediary that enables two systems to exchange data or functionality in a controlled and structured way.

How Do APIs Work?

APIs feature a set of rules that determine how programs and computers communicate. User interfaces you see on web pages or programs are designed for humans to communicate with computers. But APIs are interfaces designed for systems or programs to communicate with one another. In the chain of interaction, the API sits between the application (being used by a human) and the server.

The human user starts an API call, telling the application to perform a task. The application then uses the API to communicate with the server to process the user’s request.

A good metaphor for understanding APIs is to think of an API as a server at a restaurant. The customer places an order and the server returns to the kitchen to process and fill that order. In this metaphor, the server acts as the intermediary between the customer and the kitchen, much as the API acts as the intermediary between the user and the server.

Examples of APIs in Action

Here are a few examples of common uses of APIs:

• Login functionality: An increasing number of apps and websites allow logins with existing social accounts, such as Facebook or Twitter. This type of login functionality uses an API. The user clicks the button to log in with their platform of choice and confirms their account and password. The API communicates with the server to validate that login information and process the request to allow the login to proceed.
• Reservation booking: When booking flights, hotel rooms or dinner reservations, you may use booking apps or websites to confirm your reservation. The API confirms availability of reservations in your selected timeslots. Travel services especially rely on APIs for their bookings because they allow machines to rapidly exchange data and requests, such as flight availability and requested reservations.
• Weather forecasts: Many websites have built-in weather widgets. If you have a smartphone, you probably also have a weather app. These features use APIs to gather weather details for the user’s specified location from a third party and then deliver them back to the user.
• Map applications: The map applications you use on your smartphone rely on APIs to deliver accurate directions and location data. Users submit addresses for directions, the API communicates with the server and then brings the directions back to the user. Other websites and applications can embed Google Maps widgets into their platforms, using an API to draw data from the Google Maps servers to deliver to their users.

Types of APIs

There are several main categories of APIs: public, private, partner and composite.

• Public APIs are available for use by any third-party developer. These APIs can be free for use or proprietary APIs owned by a developer and available for purchase or subscription.
• Private APIs are specifically designed for in-house use to improve the organization’s services or operations. In-house developers or contractors hired by a company might use private APIs to integrate internal IT systems and applications or to build entirely new systems. All private APIs are, by definition, only available for those working with the developer.
• Partner APIs are promoted publicly but shared only with partners that have a signed contract with the API developer. This type of API is most likely to be used in a scenario in which two different parties need to integrate their software.
• Composite APIs are designed to group multiple API requests into a single call. This allows for more efficient operation. One API request can comprise multiple tasks or information requests while returning a single response to the user.

What is an API Endpoint?

An API endpoint is a specific URL or URI (Uniform Resource Identifier) within an API where requests are sent to access resources or perform actions. It represents one end of a communication channel between the client and the server, enabling interaction with the API to either retrieve, modify, or delete data, or perform specific operations.

API endpoints are important to businesses to keep an eye on. API endpoints can make systems vulnerable to attacks, so API monitoring is imperative. Additionally, API endpoints can get a lot of traffic, which can cause bottlenecks if not monitored properly.

What are the Types of API Architectures?

1. REST (Representational State Transfer)

• Overview: REST is the most widely used API architecture, designed around resources and stateless communication. REST APIs use standard HTTP methods (GET, POST, PUT, DELETE) to perform operations on these resources, and data is typically exchanged in formats like JSON or XML.
• Key Characteristics:
  • Statelessness: Each request from a client must contain all the necessary information for the server to understand and process it. The server does not store client context.
  • Resource-Based: Resources (e.g., users, products) are identified by URLs.
  • Scalability: REST is highly scalable because it’s based on standard web protocols.
  • Caching: Responses can be cached to improve performance.
• Use Cases: Web services, mobile applications, and public APIs (e.g., Twitter API, Google Maps API).

Example of a RESTful API Endpoint:

GET https://api.example.com/users/123 – Fetches user data with ID 123.

2. SOAP (Simple Object Access Protocol)

• Overview: SOAP is an older, more rigid architecture compared to REST, often used for enterprise applications. SOAP APIs rely on XML for message format and follow a strict set of rules. SOAP supports more complex messaging patterns (e.g., message security, transaction control).
• Key Characteristics:
  • Protocol-Based: SOAP has a well-defined structure and uses protocols like HTTP, SMTP, or TCP.
  • Security: SOAP offers built-in security (WS-Security) and transactional reliability, making it suitable for sensitive operations like banking or payment processing.
  • Heavyweight: Requires more bandwidth and processing power than REST due to its verbose XML messages.
  • Error Handling: Built-in error handling via standardized fault messages.
• Use Cases: Applications where high security and strict standards are critical, such as financial services and government systems.

Example of a SOAP Request:

<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/">

   <soapenv:Header/>

   <soapenv:Body>

      <GetUserRequest>

         <UserID>123</UserID>

      </GetUserRequest>

   </soapenv:Body>

</soapenv:Envelope>

3. GraphQL

• Overview: GraphQL is a query language for APIs, developed by Facebook, that allows clients to request exactly the data they need. Unlike REST, where fixed endpoints return specific data, GraphQL allows clients to specify the structure of the response, minimizing over-fetching or under-fetching of data.
• Key Characteristics:
  • Flexible Queries: Clients specify exactly what data they want, and in what shape.
  • Single Endpoint: All requests are sent to a single endpoint, and the query defines what data is retrieved.
  • Self-Documenting: GraphQL APIs come with built-in introspection capabilities, making them self-documenting.
  • Real-Time Support: Through subscriptions, GraphQL allows real-time data updates.
• Use Cases: Applications where efficient data fetching is critical, such as mobile apps or dashboards where network performance is important.

Example of a GraphQL Query:

query {

  user(id: 123) {

    name

    email

    posts {

      title

      content

    }

  }

}

4. gRPC (gRemote Procedure Call)

• Overview: gRPC is a high-performance, open-source framework developed by Google. It allows for direct communication between clients and servers using protocol buffers (a lightweight binary data format). It supports multiple programming languages and is ideal for microservices architectures.
• Key Characteristics:
  • Efficient Data Format: Uses Protocol Buffers, which are smaller and faster than JSON or XML.
  • Bidirectional Streaming: Supports real-time streaming data, enabling faster communication in both directions.
  • Strong Typing: Enforces type safety, which reduces errors during runtime.
  • Multi-Language Support: Supports multiple programming languages and environments.
• Use Cases: Microservices architectures, high-performance systems, real-time systems, and inter-service communication within distributed systems.

Example of gRPC Syntax (Protocol Buffers Definition):

Copy code

service UserService {

  rpc GetUser (UserRequest) returns (UserResponse);

}

message UserRequest {

  int32 user_id = 1;

}

message UserResponse {

  string name = 1;

  string email = 2;

}

5. WebSockets

• Overview: WebSockets provide full-duplex communication channels over a single TCP connection. Unlike REST or GraphQL, which rely on request-response patterns, WebSockets allow continuous bi-directional communication between a client and server, making it ideal for real-time applications.
• Key Characteristics:
  • Real-Time Communication: Clients and servers can send and receive messages at any time, without the need for repeated HTTP requests.
  • Persistent Connection: After the initial handshake, the connection stays open, reducing latency for real-time data.
  • Event-Driven: WebSockets are ideal for event-driven applications, such as chat apps, online games, or live updates.
• Use Cases: Real-time applications like chat applications, live dashboards, collaborative tools, and online multiplayer games.

Example of WebSocket Usage:

• WebSocket URL: ws://example.com/socket
• The client and server can continuously exchange messages after the connection is established.

6. RPC (Remote Procedure Call)

• Overview: RPC allows a program to execute a procedure (subroutine) on another system as if it were a local call. The client makes a request, and the server executes the function and returns the result.
• Key Characteristics:
  • Direct Method Calls: Clients call functions/methods on remote servers as if they were local, without worrying about the underlying network communication.
  • Tight Coupling: RPC typically requires tight coupling between the client and server, making it less flexible than REST or GraphQL.
  • Synchronous and Asynchronous: RPC supports both types of communication, but it’s generally synchronous.
• Use Cases: Systems that require simple, fast remote procedure calls between two systems, like early microservices communication or legacy systems.

Example of RPC Call:

import xmlrpc.client

server = xmlrpc.client.ServerProxy("http://localhost:8000/")

print(server.add(10, 20))

7. SOAP vs. REST vs. GraphQL

• SOAP: Complex, enterprise-grade, standardized security and transactional support.
• REST: Lightweight, stateless, resource-oriented, and widely used for web services.
• GraphQL: Flexible, single endpoint, and designed for efficient data fetching.

What is an API Lifecycle?

The term “API lifecycle” refers to the phases that must occur for an API to be successfully designed and deployed.

The general stages of an API lifecycle are:

1. Planning: The business team and developers meet to discuss what’s needed and how the API can be designed to fulfill those requirements.
2. Development: The developers create the API based on those discussions.
3. Testing: Developers thoroughly test the API for functionality and performance before turning it over for implementation.
4. Deployment: The finished API is put into operation. After deployment, developers may need to create updated versions of APIs to stay current with changing needs for functionality and security.
5. Retirement: All good things do come to an end. Eventually, an API will outlive its usefulness and that will result in retiring it from service.

How Boomi Approaches API Management

The Boomi AtomSphere Platform supports customers with API management throughout the entire API lifecycle – from early concepts to retirement. Boomi configures APIs that meet clients needs and then publishes them with comprehensive security and authentication. Once the API is live, Boomi monitors APIs via traffic control and a usage dashboard.

Boomi constantly works to ensure maximum performance of your APIs and deliver the most efficient, seamless customer and partner experiences possible.

See how Boomi iPaaS empowers IT teams to manage the full API lifecycle with our API Management Demo

Check out some of our previous posts on APIs:

• What Is API Management and Why Is It Important?
• Why APIs Are Key for Modernizing Your Enterprise IT Infrastructure
• Why API Management Tools are Beneficial for Developers
• APIs and Microservices: A Catalyst for the Data-Driven Enterprise
• What Is API-led Connectivity, and Is It Right for You?