Microservices and Redis

Chris Richardson

Founder of Eventuate.io Founder of the original CloudFoundry.com Author of POJOs in Action

@crichardson chris@chrisrichardson.net http://eventuate.io

@crichardson

About Chris

@crichardson

Why microservices?

@crichardson

The monolithic architecture

Tomcat

Browser

WAR

SQL database

HTML

REST/JSON

Client App

Simple to ….

Develop Test

Deploy Scale

Catalog Module

Reviews Module

Orders Module

StoreFront UI Module

@crichardson

But successful applications

keep growing ….

Eventually, agile development

and deployment becomes

impossible

@crichardson

Microservice architecture = functional decomposition

Browser

Mobile Device

Store Front UI

API Gateway

Catalog Service

Review Service

Order Service

… Service

Catalog Database

Review Database

Order Database

… Database

HTML

REST

REST

@crichardson

Develop and deploy faster

@crichardson

Scale more easily

@crichardson

Pick the best technology

@crichardson

Microservices are not a free lunch

BUT

for most large, complex applications are good choice

@crichardson

Where does Redis fit in?

Using Redis within a service

Caching High performance messaging High performance database

Catalog Service

Catalog DB

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Using Redis for inter-service communication

API Gateway

Catalog Service

Review Service

… Service

Pub/Sub

Need Product Details X

GET /product/X

Need … Need … Need …Info Info Info

@crichardson

Redis and the API Gateway

API Gateway

Caching Rate limiting Routing

@crichardson

How to maintain data consistency?

@crichardson

Database per serviceCatalog Service

Review Service

Order Service

… Service

Catalog Database

Review Database

Order Database

… Database

How to maintain data consistency without 2PC?

@crichardson

Customer DB

How to maintain data consistency without 2PC?

Order DB

Order Service

placeOrder()

Customer Service

updateCreditLimit()

Customer

creditLimit ...

has ordersbelongs toOrder

total

Invariant: sum(open order.total) <= customer.creditLimit

?

@crichardson

Use event-driven, eventually consistent order processing

Order Service

Customer Service

Order created

Credit Reserved

Credit Check Failed

Place Order

OR

@crichardson

How to atomically update database and publish an event without 2PC?

Order Service

Order Database

Message Broker

insert Order

publish OrderCreatedEvent

dual write problem

?

@crichardson

Use event sourcing

Order Service

Order Database

Event Store

insert Order

Save OrderCreatedEvent

X Persistence and notification

@crichardson

Event sourcing: persists events NOT current state

Event table

Entity type Event id

Entity id

Event data

Order 902101 …OrderApproved

Order 903101 …OrderShipped

Event type

Order 901101 …OrderCreated Order

state total

Replay

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How to implement queries?

@crichardson

Find recent, valuable customers

SELECT * FROM CUSTOMER c, ORDER o WHERE c.id = o.ID AND o.ORDER_TOTAL > 100000 AND o.STATE = 'SHIPPED' AND c.CREATION_DATE > ?

Customer ServiceOrder Service

What if event sourcing is used?

…. is no longer easy

@crichardson

Command Query Responsibility Segregation (CQRS)

Command side

Commands

Aggregate

Event Store

Events

Query side

Queries

Materialized View

Events

POST PUT DELETE GET

@crichardson

Food to Go example - on github.com http://bit.ly/redis-pia

94619:Monday [0700_2:1430, 1130_1:1430, ...]

94619:Tuesday [0700_2:1430, 1130_1:1430, ...]

… …

Restaurant View

Updater Service

Restaurant View Query

Service

ZRANGEBYSCORE

Event Store

Restaurant events Materialized view of

restaurant locations and opening hours

GET available

restaurants

ZADD ZREM

Sorted sets

@crichardson

Summary

Organize into small, agile, autonomous teams responsible for one or more microservices Use an event-driven architecture, based on event sourcing and CQRS Use Redis throughout a microservices architecture

Thank you!

@crichardson

http://eventuate.io