Token-Based Cache Invalidation for API Data Freshness

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Solution Overview

Problem

Current content delivery networks (CDNs) face inefficiencies in accelerating traffic for non-store or explicit-TTL caching approaches, particularly for content accessed through application programmer interfaces (APIs), where conventional caching methods fail to balance latency and data freshness.

Innovation Solution

Implementing a caching model that supports indefinite caching periods with notification-based invalidation, using tokens to annotate responses and control caching behavior, allowing for flexible and database-agnostic caching that remains valid until underlying data changes, thereby accelerating API traffic without relying on time-expiration based methods.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If conventional time-to-live (TTL) based caching is used, then content delivery speed is improved, but data freshness deteriorates because cached content becomes stale after TTL expires

Engineering Contradiction:

Improvecontent delivery speedVSAvoiddata freshness

Core Design Contradiction:

SpeedVSLoss of information

Solution Approach 1:

The system implements feedback through token invalidation mechanisms where the origin server sends invalidation tokens to CDN caches when content changes. This feedback loop allows caches to know when their cached content is no longer fresh, enabling them to revalidate or refresh content proactively rather than waiting for TTL expiration, thus maintaining both speed and data freshness

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system performs preliminary action by pre-fetching and caching content before it is actually needed, using URL pattern matching and predictive algorithms. This allows the CDN to have content ready in advance, improving delivery speed while the invalidation mechanism ensures freshness by replacing cached content when underlying data changes

Inventive Principle:

Principle #10Preliminary action

2Loss of information

If non-store caching approach is used for API traffic, then data freshness is maintained, but content delivery speed deteriorates because every request must be validated with the origin server

Engineering Contradiction:

Improvedata freshnessVSAvoidcontent delivery speed

Core Design Contradiction:

Loss of informationVSSpeed

Solution Approach 1:

The system applies partial caching by caching only certain API responses that are determined to be cacheable through URL pattern matching and response analysis. Not all API traffic is cached - only those that meet specific criteria, allowing the system to maintain data freshness for uncached requests while improving speed for cached ones, thus applying the action partially rather than universally

Inventive Principle:

Principle #16Partial or excessive action

3Ease of operation

If explicit-TTL caching is used, then cache management is simplified, but flexibility in controlling cacheability deteriorates because content must be cached for fixed time periods

Engineering Contradiction:

Improvecache management simplicityVSAvoidcacheability control flexibility

Core Design Contradiction:

Ease of operationVSAdaptability or versatility

Solution Approach 1:

The system implements dynamic cache management where caching behavior is not fixed but adapts based on content characteristics, request patterns, and invalidation signals. The cacheability of content is determined dynamically through analysis of response headers, content type, and invalidation token reception, allowing the system to adjust caching strategies in real-time rather than relying on static TTL configurations

Inventive Principle:

Principle #15Dynamics

4Reliability

If token-based invalidation is implemented, then cache accuracy is improved by rapidly updating cached content, but system complexity increases due to the invalidation token mechanism

Engineering Contradiction:

Improvecache accuracyVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The system uses invalidation tokens as intermediaries between the origin server and CDN caches. These tokens serve as a simplified communication mechanism that conveys content change information without requiring complex real-time synchronization protocols. The tokens act as mediators that trigger cache invalidation or revalidation, improving cache accuracy while keeping the implementation relatively simple through standardized token handling

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS10404820B2Systems and methods for controlling cacheability and privacy of objects

Publication Date: 2019.09.03 AKAMAI TECHNOLOGIES INC

AI summary

Described herein are systems, devices, and methods for content delivery on the Internet. In certain non-limiting embodiments, a caching model is provided that can support caching for indefinite time periods, potentially with infinite or relatively long time-to-live values, yet provide prompt updates when the underlying origin content changes. Origin-generated tokens can drive the process of caching, and can be used as handles for later invalidating origin responses within caching proxy servers delivering the content. Tokens can also be used to control object caching behavior at a server, and in particular to control how an object is indexed in cache and who it may be served to. Tokens may indicate, for example, that responses to certain requested URL paths are public, or may be used to map user-id in a client request to a group for purposes of locating valid cache entries in response to subsequent client requests.