Dwp from monolithtomicroservices

Department for Work & Pensions 1

From Monolith to Microservicesby Andrew Rea


From Monolith to Microservices by Andrew Rea

Know your MonolithAPI CONUSMERS

APPLICATION

DATABASE

API

BUSINESS LOGIC

DATA ACCESS

PRESENTATION

APIAPI

DATABASE

Service 1 Service 2 Service “n”

DB DB DB

Service 1 Service 2 Service “n”

Access

Postgres

MSSQL

WORD DOCUMENT

EXCEL DOCUMENT

VBA

APPLICATION

UI Business Logic

Data Access Database

Logging Reports

Open Monolith Database Monolith Distributed Monolith

Paper Monolith Office MonolithClosed Monolith



That’s another fine mess you’ve gotten me into

APPLICATION

DATABASE

CODE

CODECODE

CODE

TABLE

TABLETABLE

TABLE

STRONG CODE COUPLING STRONG DB COUPLING DATABASE COUPLING NO DOMAIN BOUNDARIES IMPLICIT RELATIONSHIPS



That’s another fine mess you’ve gotten me into

APPLICATION

DATABASE

CODE

CODECODE

CODE

TABLE

TABLETABLE

TABLE

£ £ £INCREASES COST

INCREASES IMPLEMENTATION TIME

DECREASES VELOCITY

INCREASES RISK

INCREASES DEPLOYMENT SIZE

INCREASES COMPLEXITY

INCREASES CODE FEAR

INCREASES BUILD TIME

INCREASES TEST TIME



Microservices?APPLICATION

DATABASE

SERVICE

SERVICESERVICE

SERVICE

TABLE TABLE

TABLE

TABLE

NOT YET BUT…THIS IS MANAGEABLE



APPLICATION

DATABASE

SERVICE

SERVICESERVICE

SERVICE

TABLE TABLE

TABLE

TABLE

Microservices?NOT YET BUT… THIS IS MANAGEABLE

LOOSE COUPLING HIGH COHESION ENCAPSULATION DATABASE DECOUPLING DOMAIN BOUNDARIES EXPLICIT RELATIONSHIPS SERVICE INTEGRATION SERVICE COMPOSITION



What are Microservices?

SMALL

HOW SMALL?

INTEROPERABLE

HOW?

INDEPENDENT

HOW?

A REASON TO RE-STRUCTURE YOUR TEAMS

WHY? RESILIENT

HOW?



How do you get there?

GOOD DESIGN PRACTICES& PRINCIPLES



SEPARATE PROCESS PER SERVICE

APPLICATIONS

DATABASES

TABLE

TABLE

EASIER TO ADOPT DIFFERENT TECH

INDEPENDENTLY HOSTED

INDEPENDENTLY DEPLOYABLEINDEPENDENTLY SCALABLE

SERVICE SERVICE

SERVICE

SERVICE

GRAPHKEY / VALUEDOC



INDEPENDENT - HOW?

DEVELOP INDEPENDENTLY

DEPLOY INDEPENDENTLY

BUILD INDEPENDENTLY

OPERATE INDEPENDENTLYMONITOR INDEPENDENTLYSURVIVE INDEPENDENTLY

VERSION INDEPENDENTLYPROCESS

CONTINUOUSINTEGRATION

CODE REPOSITORY

DATA STORES

CONTAINER IMAGE

SERVICEDISCOVERY

DNS (A-RECORD)

QUEUES

PROVISIONINGSCRIPTS

CERITIFICATES

LOGICAL Encapsulation

Boundary

REQUIREMENTS

LOAD BALANCERPOOL

MONITORINGGROUP

SERVICE

PHYSICAL Encapsulation

BoundaryVERSION



INTEROPERABLE - HOW?

COMMON TRANSPORT PROTOCOL

RESTFUL API

PUBLISH AND SUBSCRIBE CAPABILITY

EVENT STREAM

STRUCTURED LOGGING IN COMMON FORMAT

SERVICE

RESTFUL API OVER HTTPS

COMMANDS QUERIES EVENTS

STD OUTMETRICS STD ERROR

LOG AGENT LOG AGGREGATOR



SEPARATE SERVICES BY BUSINESS CAPABILITY

SERVICE

DOMAIN 1

DOMAIN 2

DOMAIN 3

SERVICE 1

DOMAIN 1

SERVICE 2

DOMAIN 2

SERVICE 3

DOMAIN 3

Monolith Microservices



HOW DO THEY SCALE?

SERVICE

DOMAIN 1

DOMAIN 2

DOMAIN 3

SERVICEDOMAIN 1

SERVICEDOMAIN 2

SERVICEDOMAIN 3

SERVICE

DOMAIN 1

DOMAIN 2

DOMAIN 3

SERVICE

DOMAIN 1

DOMAIN 2

DOMAIN 3

SERVICEDOMAIN 3

SERVICEDOMAIN 1

SERVICEDOMAIN 3

SERVICEDOMAIN 3

SERVICEDOMAIN 3

SERVICEDOMAIN 2

SERVICEDOMAIN 2

SERVICEDOMAIN 1

Monolith Microservices

SAVES MONEY



DOES THIS HELP SECURITY?WE CAN DEPLOY SEPARATE INSTANCES OF THE SAME SERVICE IN DIFFERENT SECURITY ZONES TO MATCH

THE SENSITIVITY OF THE DATA WHICH THE SERVICE INSTANCE WILL BE HANDLING.

TRUST 1 TRUST 2

SERVICESEARCH

SERVICESEARCH

SERVICESEARCH

SERVICESEARCH

SERVICESEARCH

SERVICEBOOKING

SERVICEBOOKING

SERVICEBOOKING

SERVICEAVAILABILITY

SERVICEAVAILABILITY

SERVICEAVAILABILITY

SERVICEAVAILABILITY

DMZ

SERVICESEARCH

SERVICEBOOKING

SERVICEAVAILABILITY



SEPARATE BUILD PIPELINES

SERVICE 1

SERVICE 2

SERVICE 3

COMMIT FUNCTIONAL NON-FUNCTIONAL SMOKE TESTSRELEASE

SERVICE 1

SERVICE 1

SERVICE 1

SERVICE 1

INDEPENDENT BUILD PIPELINESINDEPENDENT BUILD SCRIPTSINDEPENDENT PROVISION SCRIPTSISOLATED TEST ENVIRONMENTS



SEPARATE SOURCE CONTROL

SERVICE

SERVICE

SERVICE

SERVICE

SERVICE

SERVICE SERVICE SERVICE

SERVICE SERVICE

GIVE EACH SERVICE ITS OWN SOURCE REPOSITORY



SEPARATE SOURCE CONTROL

GIVE EACH SERVICE ITS OWN SOURCE REPOSITORYTEAMTEAM

TEAM

SERVICE

SERVICE

SERVICE

SERVICE

SERVICE

SERVICE SERVICE SERVICE

SERVICE SERVICE

WhoOwnsThis?



A REASON TO RESTRUCTURE YOUR TEAMS

SERVICEAVAILABILITY

SERVICEBOOKING

SERVICESEARCH

SERVICEPROVIDERS

SERVICESEARCH

SERVICEPROVIDERS

SERVICEAVAILABILITY

SERVICEBOOKING

SERVICE (NOT COMPONENT) TEAMSFEATURE TEAMS

OR BOTH?BOTH CAN PLAY A VALUABLE PART IN A MICROSERVICES ARCHITECTUREBOTH HAVE THE SAME TEAM STRUCTURE

PULL REQUESTS ANYONE?



HOW SMALL (OR LARGE)?

2000 LINES OF CODE?

TWO PIZZA TEAM SIZE?

CAN BE RE-WRITTEN IN TWO WEEKS?

MODELS A SINGLE CONTEXT?

HOW ABOUT ALL OF THE ABOVE?What thought processes do the above questions trigger about your design?

TOO BIG? MAKE SMALLER, TOO SMALL? MAKE BIGGER



HOW DO THEY COMMUNICATE

CALL

CALL

CALL

SERVICEDOMAIN 1

SUBSCRIBE

SUBSCRIBE

SUBSCRIBE

CALL

CALL

CALL

OR BOTH

DIRECT INVOCATION EVENT DRIVEN

SERVICEDOMAIN 1

SERVICEDOMAIN 2

SERVICEDOMAIN 3

SERVICEDOMAIN 4

SERVICEDOMAIN 2

SERVICEDOMAIN 3

SERVICEDOMAIN 4



WHAT ABOUT MONITORING?

CALL

CALL

CALL

META ENDPOINTSMESSAGE CORRELATIONSYNTHETIC MONITORING

HEALTH CHECK

METRICS

INFORMATION

STRUCTURED LOGGINGBUSINESS APPLICATION INFRASTRUCTURENETWORK

LOCAL -> AGENT -> REMOTE



HOW DO CONSUMING APPS GET STABILITY?

SERVICE

DOMAIN 1

Stable Next Latest

CONSUMER A

DEVELOPERS

VERSIONS WITH DIFFERENT LEVELS OF STABILITY

Consuming “Stable” in Production

Testing integration with “Next”

Researching “Latest”



HOW TO VERSION THE SERVICES?

<MAJOR>.<MINOR>.<PATCH>-<TAG>

https://medium.com/javascript-scene/software-versions-are-broken-3d2dc0da0783#.wcyli1rt2

http://semver.org

<BREAKING>.<FEATURE>.<FIX>-<TAG>

EXAMPLES

v1.0.1 v2.0.1-alpha v2.0.1-beta v2.1.0-latest



RESILIENT?DOWNSTREAM

SYSTEMS

CIRCUIT BREAKER

CONFIRMATION BULK HEADS

HEALTH CHECKSALIVE READY

EXTERNAL PERSISTENCE

ACKNOWLEDGEMENT

STATE EVENTS

STATELESS

AUTO-RECOVERY



RESILIENT?DOWNSTREAM

SYSTEM

DOWNSTREAMSYSTEM

TEST HARNESS

SWITCH OUT REALSYSTEM WITH A HARNESS RANDOM

STATUS CODE TEST HARNESS

SLOW RESPONSE

TEST HARNESS

HUGE RESPONSE

TEST HARNESS

EMPTY RESPONSE

TEST HARNESS

BAD GATEWAY

RESPONSE TEST

NO RESPONSE TEST HARNESS

HOW WILL THE SERVICE RESPONDTO ABNORMAL SYSTEM DEPENDENCIES?

LETS FIND OUT BEFORE WE GO LIVE!



RESILIENT?

SERVICE TESTING UNIT TESTING INTEGRATION TESTINGACCEPTANCE TESTING

MUTATION TESTING FUZZING TESTINGSTATIC CODE ANALYSIS

PERFORMANCE TESTING LOAD TESTING STRESS TESTING IMPULSE TESTING LONGEVITY TESTING

FAILURE TESTING

SECURITY TESTING

SMOKE TESTING

RELEASE TESTING ROLLBACK TESTING

FUNCTIONAL

CROSS FUNCTIONAL



WHEN SHOULD THE TEAM DEPLOY?

WHEN CAN THE TEAM DEPLOY?



A LOT OF THIS IS NOT NEW

GOOD DESIGN PRACTICES & PRINCIPLES

BUT THEY DON’T COME FOR FREE!



CHEAT SHEET

EXTERNAL

INTERNAL

AGGREGATIONCORRELATIONVISUALIZATION

REPORTING

API

LOGG

ING

DATAM

ESSA

GING

APPLICATION

INTEGRATION

OPERATION

HTTPSXML JSON

SOAP REST

THROTTLING AUTHENTICATION AUTHORIZATION

CIRCUIT BREAKER

INSPECTION ROUTING

CIRC

UIT

BREA

KER

BULK HEADS

CIRCUIT BREAKERBULK HEADS BU

LK H

EADS

RELIA

BLE

MES

SAG

ING

DURA

BLE

MES

SAG

ING

HEALTH

DEPLOYMENT SERVICE REGISTRATION

CONFIGURATION READINESS CHECKS

STRU

CTUR

ED LO

GG

ING

TIM

E SE

RIES

BUSI

NES

SAP

PLIC

ATIO

NIN

FRAS

TRUC

TURE

NET

WO

RK

ERRO

R CA

TALO

G

EVEN

T CA

TALO

G

INFORMATION DISCOVERABLE API

BACK UP

SECURITYSECURITY SECURITY

TEST HARNESSES

CONTINUOUSINTEGRATION

CODE REPOSITORY

DATA STORES

Application Identity

PROTECTIVE MONITORING

COMMANDS QUERIES

EVENTS

DOMAIN MODEL

DOMAIN SERVICES

VERSIONING

DOMAIN EVENTS

CORR

ELAT

ION

ID

SERVICE DEPENDENCIES

SUBSCRIBING SERVICES

HORIZONTAL SCALING

FAILOVER

RECOVERY

PUBLISH

EVENT LOG

SUBSCRIBE

SECURITY

KEY SECURITY

ENCRYPTION IN TRANSIT

ENCRYPTION AT REST

SECURE DEVELOPMENT, DEPLOYMENT & OPERATIONAL PRACTICES AND PRINCIPLES

CONTAINER IMAGE

CONSISTENCY BOUNDARY

API GATEWAY

SERVICEFABRIC

SERVICEREGISTRY

LOAD BALANCER

WRITE STO

RE

READ STORE(S)

REVERSE PROXY

INSP

ECTI

ONAPPLICATION FIREWALLS

INSPECTIO

N

ENCAPSULATION BOUNDARY

CONTAINERREGISTRY

HEXAGANOL ARHCICTECTURE

Version 1 Microservices Infograhic by Andrew Rea

EXTERNALMONITORING

MONITORING

MONITORING

?SERVICE

DISCOVERY

DATA STORE ISO

LATION AM

QPM

QTT

HTTP

othe

r…

GRAPH

DOCUMENTKEY/VALUE

RELATIONAL

COLUMN

FLAT FILE

Dwp from monolithtomicroservices

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