@farmar#VoxxedVienna

SOA Lessons Learnt (or Microservices Done Better)

Sean Farmar

Particular Software

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Tried all “Best Practices”Layers and Tiers

Distributed monoliths using Web Services

and failed ...

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My journey to SOA

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So I went to my master

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Solve the problem you want?mmmm…

Coupling your problem is…

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Coupling

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Coupling Dimensions

Afferent (Ca)

Efferent (Ce)

What depends on you

What you depend on

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Coupling DimensionsTemporal

Time, synchronous communication, logical temporal

couplingSpatial

Physical, deployment, endpoint address

Platform Protocols, platform specific

features @farmar

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Fallacies of Distributed Computing

var svc = new MyService();

var result = svc.Process(data);

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Fallacies of Distributed Computing1. The network is reliable. (Bill Joy and Tom

Lyon)

2. Latency is zero. (Bill Joy and Tom Lyon)

3. Bandwidth is infinite. (Bill Joy and Tom Lyon)

4. The network is secure. (Bill Joy and Tom Lyon)

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Fallacies of Distributed Computing5. Topology doesn’t change. (Peter Deutsch)

6. There is one administrator. (Peter Deutsch)

7. Transport cost is zero. (Peter Deutsch)

8. The network is homogeneous. (James Gosling)

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Fallacies of Distributed Computing

Fallacies ebook(David Boike): http://go.particular.net/voxxedv17

Ted Neward’s blog: http://blogs.tedneward.com/post/enterprise-computing-fallacies

/

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Why Microservices?Break down the monolith

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Monolith

UI

BL

DAL

DB

Tight CouplingLoose Coupling

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Vertical Slicing

UI

BL

DAL

DB Referential Integrity

Tight CouplingLoose Coupling

Re-introduces Coupling

SalesConte

ntCRMOps

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Why SOA

“Address coupling in our software design by building loosely coupled and highly encapsulated components”

Udi Dahan

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Encapsulation

AutonomyDecomposing business entities

by properties/fieldsBounded context == high coupling

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Design

Don’t generalise, be explicit SRP (Single Responsibility Principle)Keep your vertical slice thin, top to

bottom

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Lessons learnt

It’s hard (er)Asynchronous fire and forget,

Pub/SubSeparating data writes and data

reads (CQS)

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Lessons learnt

No silver bullet: use messaging only if it suites

Decomposing your business domain is hard, no framework/tools will

magically fix that

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Lessons learnt

Data (write) ownershipReferential integrity and GUIDS

Data reads and eventual consistency

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Lessons learnt

Monitoring - Lights onTesting is HARD

Deployment - Automate everything

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Lessons learnt

Organization and people, trustBe pragmatic but keep the paradigm

Build your business not a system

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SummaryAvoid all dimensions of coupling

Avoid synchronous communication between components/microservices,

Don't share data, use view/read models to share read only data

You can do it on .Net platform using NServiceBus

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Q&ABlog post:

http://particular.net/blog/goodbye-microservices-hello-right-sized-services

Fallacies EBook: http://go.particular.net/voxxedv17

NServiceBus:http://particular.net

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Thank You!Sean Farmar

Particular.net

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