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Table of contents

• Introduction
  • What is ha-store
  • The competition
• Concepts
  • Coalescing
  • Batching
  • Retrying
  • Circuit-breaking
  • Micro-caching
• Formulas
  • Calculating the Zeta distribution
  • Optimizing ha-store settings
• Samples
  • Express+Mongo
• References
  • Micro-caching white paper

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Introduction

What is ha-store

ha-store, or High-Availability store, is wrapper to abstract common optimization and security patterns for data fetching.

It's goals are to

• Decouple performance, security and degradation fallback concerns from the rest of the application logic.
• Provide an extensible interface to control caching, batching, retrying and circuit-breaking.
• Reduce the infrastructure-related costs of orchestration-type applications with smart micro-caching.

The competition

Facebook's dataloader is a close competitor, but it lacks a few key features.

dataloader's documentation suggests implementing a new instance on each request, only coalescing data queries within the scope of that request- with a batching frequency that runs on node's event-loop (nextTick). This approach fits their caching strategy, since they do not have micro-caching, they are forced to make their entire stores short-lived so that they do not cause memory concerns.

ha-store, on the other end prefers global, permanent stores. This means that data query coalescing is application-wide, with the batching tick rate customizable- to allow users to really optimize roundtrips.

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Concepts

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Formulas

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Samples

Express+mongo

Includes all of the ha-store features (retry, circuit-breaker, batching, coalescing, caching) in this very classical Express+Mongo application: Gist

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References