microservicesan agenda for a new architecture

who am I? Twenty years experience working in distributed systems

Slowly getting better at it

Background: integration, SOA, Event Processing, BPM, CAD/GIS, Astrophysics

CTO at Sixtree: sixtree.com.au Editor at InfoQ: infoq.com/author/Saul+Caganoff Blogger since 2007: soabloke.com Twitter: @scaganoff

overviewTo set out an agenda and discussion programme for microservices melbourne

a little philosophy a little reflection what’s happening?

a little philosophy Epistemology: how do we gain knowledge?

Truth vs BeliefKnowledge vs Luck

scientific method Karl Popper (1935):

Theories can never be proven, only falsified.

Thomas Kuhn (1962):Scientists work within a “paradigm,” a set of rules & regulations that

defines boundaries and; describes how to behave inside those boundaries.

Paul Feyerabend (1975):There is no method. It’s all just “marketing”

the copernican revolution

1543

1687

how is this relevant to IT? Truth? But you can’t measure productivity

...or quality

Software is a social process

...you cannot separate method from culture

...organizational change = “you're not doing it right”

It takes a long time for knowledge to converge

…in that time tools/techniques have moved on

Is IT merely fashion?

crisis & change Crisis

Discrepancy between theory and fact Change in social/cultural climate

Change Paradigms are resistant/resilient to change Failures take a long time to build momentum

Shift New candidate emerges and a battle ensues Often the old paradigm doesn't die out completely

application architecture shifts Mainframe to Client/Server

Crisis: scarcity of compute resources

Enabler: Emergence of PCs and midrange computers

Impact: $$$ shifted from hardware to software

World Wide WebCrisis: Content distribution, e-commerce

Enabler: HTTP, HTML

Impact: $$$ shifted online

The current shift…Crisis of agility: change takes too long and costs too much

Enabler: Commodity hardware, Virtualization, SOA, DevOps

Impact: ….

many interacting shifts

On-Premise → Cloud Hosted

Owned → Pay per use

Physical → Digital

Local → GlobalSequential → Concurrent

Scale-up → Scale-out

Static → Mobile

Centralized → Distributed

Waterfall → AgileAssembly Line → TQM

the current crisis Business Agility, speed of change

The big ball of mud

Scalability a global user-base flavours: differential, elastic

Commodity vs Differentiation Does IT matter?

the monolith Have we been working with the wrong level of abstraction?

The bigger an application becomes, the harder it is to change.

Services feel like the right level of abstraction but there is a mismatch with the way applications are currently packaged and delivered.

Very coarse differentiation between “commodity capabilities” and “defining capabilities” (e.g. pace layering).

the leap of faith The gap between business requirements and what an

application vendor offers.

the leap of faith Snip here to outsource, offshore, cloudify

CloudScale, Cost, Agility, Abundance, Ephemeral

Services as a ServiceBuy services not software

Compose “best of breed”

NoSQLDBs are cheap & malleable

Continuous DeliveryChange can be automated

AgileIncremental change

Small, productive teams

DevOpsRemove the barriers from conception to production

the opportunities

the composable enterprise The pioneers are “providers”

Amazon.com, Netflix, Warner Music Group

The mainstream will be “consumers”

…or a mixtureConsume commodity SaaS

Build their own “engines of differentiation”

So far all the talk has been about providing…consuming, not so much

what is an application anyway? First instances of the new paradigm resemble the old paradigm

What is Salesforce.com other than Siebel in the cloud? Is Netflix an enterprise or an application?

It’s hard to tell…traditional system boundaries are dissolving.

we’ve been here beforea little reflection

distributed systems frameworks The way we conceptualize distributed systems reflects our

programming languages Sun RPC/DCE – distributed procedures CORBA/DCOM – distributed objects SOAP – distributed objects + XML serialization REST – www for bots

Events, Asynchrony, Concurrency Reactive Extensions Promises CSP (Go, Erlang) – a return to 1970’s message passing paradigms?

problems with distributed systems

Classic: Serialization Interface contracts Service discovery Waldo’s fallacies State Management &

Consistency

New: Management Visibility & Responsiveness Resilience Change Coordination

waldo et al Fallacies of distributed computing

There is a single natural object-oriented design for an application regardless of the context in which it will be deployed.

Failure and performance issues are an implementation detail to be added after the initial design.

The interface of an object is independent of the context in which that object is to be used

…fundamentally: latency, performance & failure must be accounted for from the design up…

Services address Waldo because they make network boundaries explicit.

serialization A recurring problem in many systems

Sun RPC/DEC – wedded to C and Unix DCOM – wedded to C and Windows CORBA – IDL binding to multiple languages was a big problem SOAP – XML binding to multiple languages was a big problem

…mismatch between serialized objects and an XML document

JSON – better match to common language structures such as object attributes, arrays, maps

interface contracts Waldo fallacy: an object interface is independent of its context XSD fallacy: a document’s validation rules are independent of

the process context

Postel’s Law: “be conservative in what you send and permissive in what you receive…” Permissive Consumer c.f. various object serialization libraries

worry that JSON is just reinventing XML

what to consider for microservices

where to from here?

coupling vs cohesion microservices favour extreme de-coupling

….what do we trade in terms of coherence?

Database synchronization across systems of record

Code How to handle shared libraries & code change Ctrl+C/Ctrl+V = decoherence

Services Vocabularies vs shared object models

Consumer/Provider coupling – avoiding rpc

service design Granularity - how big is a “micro”?

LOC seems somewhat arbitrary

….is it more that I can throw it away without grief?

Hypermedia & HATEOAS Reiteration of object references – values vs urls

Seems like a great idea, but we are lacking good examples

Many choices: HAL, JSON.API, JSON Siren, Collection+JSON, JSON-LD

Automating consumers

Design-first specification API Blueprint, RAML, Swagger 2.0

API Evolution - versioning

development concerns Continuous Delivery

Testing Client-driven testing: PACT Integration testing

Runtime environment Naked processes Traditional containers – e.g. JVM New containers – LXC, Docker, PaaS Autoscaling

languages & frameworks What are good languages & frameworks for microservices?

….why?

Popular Go node.js Scala + Play …?

Frameworks Netflix OSS Spring Boot, Mule APIKit Seneca (node.js)

visibility & responsiveness Self-healing Services

Logging Trace, debug Metrics – response times Coordination – end-to-end

monitoring, choreography

Tools ELK: Elasticsearch, Logstash, Kibana Splunk Riemann

Alerting & Reaction Circonus

coordination Orchestration vs Choreography

Mastering asynchronous coordination Message passing Events: sourcing, processing State: application and system-wide

Layered architectures - “layers are bad” Composition is a form of re-use, so where do you define your level

of composition?

antifragile patterns

Adrian Cockroft (Netflix) – Dystopia as a Service

Cloud Native Architecture: Embrace “broken & inefficient” to deliver “sooner” and “dynamic”

"the new engineering challenge is not to construct perfection but to construct highly agile and highly available services from ephemeral and often broken components."

Microservices Reactive APIs Bulkheads Circuit breakers Chaos Monkey (and other Simians)

use-cases Greenfields applications Brownfields applications – building new microservices apps

amongst traditional apps Remediation – re-architecting legacy apps into microservices

Distributed Teams

Legacy Systems The “build” vs “buy” equation

future agenda Aim for a monthly meetup with two speakers each month Looking for speakers to discuss:

DDD API Design Languages & frameworks Development concerns Testing

Continuous Delivery Runtime Environment Monitoring & Visibility Coordination Antifragile Patterns Use-Cases/Case-Studies

and….