What is cached response?

A cached response in the context of API design refers to the practice of storing the output of an API call for a certain period, so that subsequent requests for the same data can be served more quickly from the cache rather than re-executing the entire operation on the server. This technique is used to improve performance, reduce latency, and decrease the load on the server.

Key Concepts of Cached Responses

1. Definition and Purpose:

   • Cached Response: It is the stored result of an API call that can be reused for subsequent requests without hitting the server again. This helps in reducing the time taken to fetch the data and decreases the server load[1][2][3].
   • Purpose: The main goals are to enhance performance, improve user experience, and optimize resource utilization by reducing redundant operations[1][2][3].

2. Types of Caching:

   • Client-Side Caching: This involves storing the cache data on the client’s side, such as in a user's browser or app. It is particularly useful for static or infrequently changing data[1].
   • Server-Side Caching: This involves storing the cache data on the server side, which can be done using various caching mechanisms like in-memory caches (e.g., Redis, Memcached) or disk-based caches[2][3][7].
   • Reverse Proxy Caching: This involves an intermediary server that caches responses and serves them to clients, reducing the load on the origin server[1].

3. HTTP Headers for Caching:

   • Cache-Control: Specifies directives for caching mechanisms in both requests and responses. Common directives include max-age, no-cache, and no-store[2][3][6].
   • ETag: Provides a unique identifier for a specific version of a resource, allowing clients to validate cached responses[1][6].
   • Expires: Specifies an absolute expiry time for a cached response[6].

4. Benefits:

   • Reduced Latency: Cached responses can be served much faster than generating a new response from scratch, leading to quicker response times[1][2][7].
   • Decreased Server Load: By serving cached responses, the number of requests that need to be processed by the server is reduced, which can lead to better scalability and lower operational costs[1][2][7].
   • Improved User Experience: Faster response times contribute to a smoother and more responsive user experience[1][2][7].

5. Challenges and Considerations:

   • Stale Data: There is a risk of serving outdated data if the cache is not properly invalidated or refreshed[1][7].
   • Cache Invalidation: Strategies must be in place to ensure that the cache...