REST API - Caching

Table of Contents

1. Introduction
2. Application Layer Caching
3. Request Level Caching
4. Conditional Caching
5. Cache Invalidation
   • Write-Through Cache
   • Write-Behind Cache
   • TTL-based Cache
6. Layered Caching
7. References

Introduction

Caching is a technique used to store frequently accessed data in a temporary storage location, such as memory or disk, to reduce the time it takes to retrieve that data from the original source. This improves the performance of the API and reduces the load on the server.

Source : Bytemonk

Application Layer Caching

Application layer caching is a technique used to cache the response of the API. This is done at the application level, which is the layer between the client and the server. In-memory caching is the most common application layer caching technique. Redis and Memcached are the most popular in-memory caching solutions. This reduces the load on the database and improves the performance of the API.

Request Level Caching

Request level caching is a technique used to cache the response of the API at the request level. This is done at the application level, which is the layer between the client and the server. This is mostly for read-heavy operations.

Uniques cache key

• Read-Heay APIs
• Expensive Queries
• Paginated Data

Conditional Caching

It ensures that the client recieve updated data only if it necessary. It reduces bandwidth usage and improves performance.

ETag

ETag is a unique identifier for a resource. It is a hash of the resource's content. It is used to check if the resource has been modified since the last request.

First request:

• Request:

GET /api/users/1

• Response:

200 OK
Headers: ETag: "1234567890"
Body: {
    "name": "Iraianbu",
    "email": "iraianbu011@gmail.com"
}

Second request:

• Request:

GET /api/users/1
Header: If-None-Match: "1234567890"

• Response:
  • If unchanged:

304 Not Modified

• If changed:

200 OK
Headers: ETag: "1234567891"
Body: {
    "name": "Iraianbu",
    "email": "iraianbu@gmail.com"
}

Last-Modified

Last-Modified is a header that is used to check if the resource has been modified since the last request. It is used to check if the resource has been modified since the last request.

Cache Invalidation

Cache invalidation is a technique used to invalidate the cache when the resource is modified. This is done at the application level, which is the layer between the client and the server. It is method to update or remove cached data when the underlying data changes.

Write-Through Cache

Write-Through Cache is a technique used to write data to the cache and the database at the same time.

Pros:

• Cache is always up to date with the database.
• Easy to implement.

Cons:

• Performance overhead because of the write to the database.

Write-Behind Cache

Write-Behind Cache is a technique in which cache is updated asynchronously after the database is updated.

Pros:

• Faster write operations.
• High write throughput.

Cons:

• Temporarily hold stale data.
• More complex to implement.

TTL-based Cache

TTL(Time To Live) - based Cache is a technique in which cache is expired after a certain time.

Layered Caching

Layered Caching is a technique in which cache is used at multiple layers.

• Browser Cache (Store content close to the user)
• CDN Cache (Store content close to the user geographically)
• Application Layer Cache (Store content in the application)
• Database Cache (Store content in the database)

References

• Bytemonk