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Part 3 - API Testing Interview Questions & Answers

Part 3 - API Testing Interview Questions & Answers

Naveen AutomationLabs

36:00

Overview

This video, the third in a series on API testing interview questions, delves into RESTful web services and HTTP methods. It explains the core characteristics of REST, emphasizing its stateless nature and contrasting it with stateful architectures. The discussion covers the components of an HTTP request, including methods, URIs, headers, and bodies. A significant portion is dedicated to detailing the functionalities and differences between common HTTP methods: GET, POST, PUT, PATCH, DELETE, OPTIONS, and HEAD. Practical examples and analogies are used to illustrate concepts like caching, payload limitations, and the distinction between updating entire resources (PUT) versus partial updates (PATCH). The video aims to provide practical, interview-ready knowledge beyond theoretical definitions.

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Chapters

  • •REST is stateless, meaning the server does not maintain session data or user context.
  • •Statelessness allows for easier horizontal scaling.
  • •Stateful APIs store user context on the server, leading to issues if a server fails.
  • •Stateless APIs store user context (like session IDs) in a cache or separate database, allowing any server to handle requests.
  • •An HTTP request includes a method (GET, POST, PUT, etc.), a URI to identify the resource, and the HTTP version.
  • •Headers provide metadata about the request, such as content type or authentication tokens.
  • •The request body (payload) contains data sent to the server, often in JSON or XML format.
  • •GET: Retrieves data; can be cached and bookmarked; should not be used for sensitive data.
  • •POST: Creates or updates data; generally used for creating resources; not cached or bookmarked.
  • •PUT: Replaces an entire resource with the provided payload; used for updates.
  • •PATCH: Partially updates a resource with only the specified fields.
  • •DELETE: Removes a specified resource.
  • •OPTIONS: Describes communication options for a target resource, indicating supported HTTP methods.
  • •HEAD: Similar to GET but returns only the response headers, not the response body.
  • •PUT is idempotent for updates (retrying has the same effect), while POST is not (retrying creates duplicates).
  • •POST requests are generally not cacheable, whereas PUT responses can be.
  • •GET is 'harmless' as it only retrieves data, while POST can resubmit data and create new entries.
  • •GET can be bookmarked and cached; POST cannot.
  • •GET requests have a URL length limit (approx. 2048 characters) for data, making them unsuitable for large payloads.
  • •POST requests have no theoretical limit on payload size, allowing for large data transfers in the request body.
  • •Caching stores data temporarily to improve retrieval speed, reducing server load and response times.
  • •URI (Uniform Resource Identifier) locates a resource on the server, including protocol, domain, and resource path.
  • •Payload is the actual data being transferred in an HTTP request or response, distinct from headers or metadata.

Key Takeaways

  1. 1REST APIs are fundamentally stateless, enhancing scalability by not storing client session data on the server.
  2. 2Understanding the nuances between HTTP methods (GET, POST, PUT, PATCH, DELETE) is crucial for correct API implementation and testing.
  3. 3PUT is used for full resource replacement, while PATCH is for partial updates, ensuring data integrity and efficiency.
  4. 4GET requests are safe and idempotent for retrieval and can be cached, but should not carry sensitive data or large payloads due to URL limitations.
  5. 5POST requests are typically used for creating new resources and are not cached or idempotent in the same way as PUT.
  6. 6The OPTIONS method is vital for discovering the supported operations on a specific API resource.
  7. 7Caching mechanisms significantly improve performance by storing frequently accessed data closer to the client.
  8. 8Distinguishing between URL length limits (GET) and request body flexibility (POST) is key for handling varying data sizes.
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