making the case for play framework and scala- budapest ping-conf (2014)

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Making the case for Play

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Adam Evans

Asher Glynn

CBeebies Tech Lead

Technical Architect

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CBeebies

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What is it?

• Website for children aged 4-6

• An aggregate view of BBC content

• 2 million unique users a week

• High UX demands, our audience cry’s

• Built using PHP and a long forked version of Zend MVC

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The (old) Architecture

CBEEBIES

SOLR ELECTRON NITRO GAMES GRID

PAL

RESTFUL SERVICES

FORGE

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The Issues• Large legacy codebase

• Cutting edge in BBC at time

• Original developers long gone

• Hard to work on new features with confidence

• Quality of tests vary

• Retro fitted on top

• Hard to do well with the existing codebase

• PHP’s not designed for aggregating data from multiple restful services

• Business needs have changed

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The Opportunity

“Responsive”

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What we done on our summer holiday• Clear message to management

• What the problems were

• What we should do about it

• What they should expect

• Used experience and judgement for recommendations

• Time critical - we were in trouble

• No beauty competitions

• Had clear justifications

• Confidence and decisiveness gave management confidence for a spike

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Play frameworkWhy did we choose it?

• Scala

• Full stack Web Framework

• Reactive architecture is great when calling web services, non blocking - fits

exactly our problem type

• Typed template system is amazing

• Lots of industry buzz

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The First Spike

• Addressed stakeholder concerns:

• Business value of the product is in the front end

• Could show (visually) immediate progress

• Backends aren’t (visually) impressive

• Created responsive templates from a mocked data layer

• Setup basic build pipeline to AWS - immediate productivity impact

• Demonstrated skills transfer to existing team members

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The First Spike

• Success!!!

• Compelling enough to have our stakeholders commitment

• A 2 man team of Java/Scala + PHP/Javascript

• Collaborate effectively

• Become productive quickly

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Moving forward

• How do we take a team of developers into Scala?

• How do we resource?

• How do we manage the risks?

AND

• How to migrate smoothly from the previous Apache/Tomcat platform???

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The Team

• Started small - 3 developers

• Split frontend/backend

• PHP focused on front end to get familiar (avoid Scala overload)

• Backend started out Java-like with Scala’s syntactical sugar

• Big recruitment drive

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The New Architecture

• Version Control - GIT

• Build - Jenkins

• Deployment - AWS

• Continuous Delivery (almost)

• App and Web server - Play 2

[Should be pretty diagram here]

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… after rethinking

Varnish

Nginx + mod_pageseed

Play

Nginx + mod_pageseed

Play

Started with Ended with

AWS ELB

Play Play

…overthought the problem

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Risky business

• Heavy use of Java in the BBC. Extensive expertise on the JVM

• Already some use of AWS for internal systems

• Extensive change was unavoidable - regardless of the change was

We’re doing things differently not necessarily new (Going outlaw but in a nice Robin Hood kind of way)

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The approachNo more tears - set by Editorial children's not developers tears

(or product managers or development managers)

• Iterative • Discrete • Tough editorial demands • Tough editorial timeframes • Tough audience!

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The approach• Distinct vertical sections

• A section at a time

• Updated content item pages first

• Index pages after content pages

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The approach

Default Theme Templates

Data Access Libraries/Templates

Game Songs Makes Storie Watch Radio Shows

DAO/ Templates

DAO/ Templates

DAO/ Templates

DAO/Templates

DAO/ Templates

DAO/ Templates

Vertical Plugins

DAO/ Templates

Horizontal Plugins

• Play allows modularisation

• Can develop in isolation

• Can deploy in isolation

• Can test in isolation

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Keeping it real (simple)

• Local in memory cache • Used Guice rather than Cake • Simpler, less boilerplate • More familiar for Java devs • Runtime configuration changes possible

• Opted out of some “kitchen sink” components in Play • Started at the view/templates to drive design

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Where we are now

• We have our first live release.

• First public facing AWS + Scala Application

• Management buy in for new model with Continuous Delivery

• Stakeholders very happy with turnaround of features

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Things we’ve learnt

• Hit a few small bugs in Play

• Open source makes it easier to find root cause

• Vast number of base libraries/products

• Constantly learning

• Scala’s cool factor makes it easier to recruit

• Some things are hard to test in Play out the box

• It’s easy to get carried away with idiomatic Scala

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• Constant engagement with stake holders managing a risky move

• PHP Developers have found it hard

• Syntax / FP concepts appear scary/overwhelming

• Patterns such as DI are new

• Lots of Scala tries to be academically clever

• Java developers

• Find certain aspects hard being different (testing)

• Can sometimes get carried away with new power sacrificing simplicity