News KrakenD CE v2.7 released with better rate-limiting and security options

Understanding API Calls: The KrakenD Approach

by Albert Garcia

Jun 5, 2023

6 min read
post image

KrakenD, a market leader in high-performance API Gateway solutions, enables seamless and efficient API interactions within today’s complex digital landscape. This comprehensive guide delves into the intricate details of API calls and their pivotal role within the microservices architecture, specifically in a KrakenD environment.

Understanding API Calls: The Essence of Software Interactions

APIs, or Application Programming Interfaces, form the core of sophisticated software interactions, providing the pathways for communication between different software modules. API calls serve as the couriers of these pathways, transmitting instructions for task execution.

Dissecting an API Call: The Fundamental Elements

An API call is composed of several key elements:

  • Endpoint: The specific URL designated for API interaction.
  • Method: The action type desired from the API. Common methods encompass GET, POST, PUT, and DELETE.
  • Headers: Parameters that provide contextual information for the request, such as content type or authentication tokens.
  • Data/Body: Contains the core information or instructions to be sent, applicable for POST and PUT methods.

Example of an API call using curl:

Example API Call 
$curl -X POST \
  -H "Content-Type: application/json" \
  -d '{"id": 1234, "username":"krakend-user"}' \

Lifecycle of an API Call in KrakenD

Understanding the journey of an API call—from initiation to response receipt—is essential to ensuring efficient system interactions within KrakenD.

Initiation Stage in KrakenD

In a KrakenD environment, an API call commences with a structured request from client software to the KrakenD API Gateway. This request aligns with the HTTP protocol and principles of the REST architectural style.

KrakenD takes the incoming API calls and, depending on the configuration, might aggregate results from several different endpoints before returning a consolidated response. This reduces the complexity of client-side operations, enabling smoother and faster interactions.

Response Receipt and Decoding in KrakenD

Following initiation, KrakenD returns a response comprising an HTTP status code reflecting the request’s success or failure, and where applicable, relevant data in the response body.

HTTP status codes give users insight into the results of their request. Some common codes include:

  • 200 OK: The request was successful, and the response body contains the requested data.
  • 401 Unauthorized: The request requires user authentication.
  • 404 Not Found: The server could not find the requested resource.
  • 500 Internal Server Error: The server encountered an unexpected condition which prevented it from fulfilling the request.

KrakenD optimizes the response delivery by removing unnecessary fields and ensuring the client receives a clean, streamlined response. Here’s an example response:

HTTP/1.1 200 OK
Date: Tue, 02 Aug 2023 09:28:53 GMT
Server: KrakenD Version 1.4.0
Content-Type: application/json
Content-Length: 49
    "id": "1234",
    "username": "krakend-user",
    "other": "fields"

In this response, we see a status code of 200, indicating a successful request, and the body of the response contains a username and a token. This means that our API call was successful, and the server has returned the requested data.

It’s important to understand the meaning of these HTTP status codes, as they can guide users in diagnosing and fixing any issues that might arise in their API calls.

Error Management in KrakenD

API calls may occasionally encounter errors due to factors like an incorrect endpoint, an invalid method, or insufficient authorization. Within KrakenD’s ecosystem, understanding these error messages is key to resolving issues and ensuring successful API calls.

KrakenD offers a range of error handling features to ensure users can quickly identify and resolve issues. From detailed error logging to robust retry mechanisms, KrakenD is built to help manage the unpredictable nature of distributed systems.

API Calls and Microservices Architecture: A Symbiotic Relationship

API calls are integral to a microservices architecture, a model embraced for its flexibility and scalability. API calls enable communication among services, augmenting functionalities, enhancing integration, and promoting interoperability. They provide a robust foundation for scalable applications tailored to dynamic business needs.

KrakenD shines as a facilitator in this scenario, acting as a single entry point to all your microservices. It consolidates and manages the communication between the client and multiple services, providing load balancing, failover, circuit breaking, and rate limiting functionalities out of the box, optimizing the API calls flow.

Harnessing the Power of API Calls with KrakenD

API calls underpin digital interaction, creating a seamless communication path between diverse software applications. A solid understanding of their structure, execution process, and response interpretation can significantly aid in managing complex digital ecosystems.

KrakenD’s stateless, distributed, high-performance API Gateway maximizes the potential of API calls, enabling true linear scalability and facilitating smooth adoption of microservices. Harnessing API calls effectively is a cornerstone of creating resilient, integrated software solutions.

KrakenD is a powerful ally in mastering API calls, providing enhanced visibility, control, and scalability, empowering you to navigate the digital landscape with confidence.


API calls are not just mere software interactions; they are pivotal elements in constructing resilient and adaptive digital ecosystems. With KrakenD, understanding and mastering API calls becomes accessible and convenient. The versatility and power of the KrakenD API Gateway offer an unrivaled platform for leveraging API calls to their fullest potential, ensuring true linear scalability, and fostering a seamless transition to a microservices architecture.

Armed with this knowledge, you are better equipped to navigate the complex world of API calls and microservices, ensuring your organization remains at the forefront of technological innovation.

Frequently Asked Questions (FAQs) about API Calls

What is an API call?

An API call is a process that sends a request to a server using an Application Programming Interface (API). The server then responds to the request, completing the API call. It essentially is a communication method between two software components.

Why are API calls important in a microservices architecture?

In a microservices architecture, each microservice is a self-contained unit providing a unique functionality. API calls are the mechanisms that allow these distinct microservices to communicate and coordinate, effectively linking these individual functionalities into a coherent system.

How does KrakenD optimize the execution of API calls?

KrakenD, as a high-performance API Gateway, acts as a middleware between client software and microservices. It consolidates requests and responses, reducing the number of API calls required and enhancing the system’s overall performance and scalability.

What common errors can occur during an API call?

API call errors can result from several factors, including incorrect endpoints, invalid methods, or lack of proper authentication. Understanding and interpreting error messages is crucial for quick resolution and efficient software communication.

How does understanding API calls benefit my organization?

A comprehensive understanding of API calls enhances your ability to manage software interactions and address potential issues swiftly. With the role of digital services growing, effectively managing API calls becomes vital to maintaining a robust and adaptive software infrastructure.

 Stay up to date with KrakenD releases and important updates