How Fervo builds web apps

Transcript

1. How Fervo builds web apps Magnus Nordlander
2. Magnus Nordlander • PHP consultant and CEO with Fervo • Worked with PHP for well over 10 year, Symfony for over 9 years.
3. • Small consultancy specialized in 
 modern PHP, Symfony in particular • Three PHP consultants, two
 Symfony certed • Read more at fervo.se
4. Index • Technology radar • Tech Stack • Development methodology • Software architecture
5. Index • Demo of our code structure in practice • Questions
6. Preface • I’m gonna introduce a lot of concepts • I could easily spend 45 minutes per concept or do a multi-day workshop on this • My goal is to pique your interest, so that you want to learn more
7. Preface • Small projects require less structure • Some of the advice within this presentation is more appropriate for large projects • Your mileage may vary
8. Technology Radar
9. Maturity • Generally recommended • Under trial • Promising • Interesting
10. Tech stack
11. Tech Stack • PHP 7 is generally recommended, subsetphp is interesting • HHVM has been promising for a long time, but as PHP7 has become better, the need has diminished • Linux is generally recommended for servers • We prefer Postgres, but MySQL is fine too
12. Tech Stack • Redis is great • Several mature Document oriented databases, but which one to choose depends • ElasticSearch is awesome for search • We love Heroku, and we're fond of AWS.
13. Tech Stack • We're all using Docker for our dev environments • Docker for Mac is interesting, but not good enough yet • Docker in production is very interesting, and we hope to use it in a client project soon
14. Tech Stack • We generally recommend php-fpm • There have been interesting developments for a long time in serving requests from within PHP • Leach (0MQ) • ReactPHP / PHP-PM • PHPFastCGI
15. Development methodology
16. Development methodology • We don't believe in waterfall • We generally recommend BDD, both Story BDD and Spec BDD • Communication and collaboration is key
17. Communication
18. BDD • Behavior driven development • TDD “done right” • TDD + DDD + OOA&D => BDD • Many pay lip service to testing, BDD gives immediate rewards, encouraging adoption
19. Story BDD • Capture business requirements in a testable format • Written in business readable, ubiquitous language • Behat is a great tool for Story BDD, just make sure you run Behat 3
20. Story BDD
21. Spec BDD • Specifies what a class should do and how it should interact with other classes • PHPSpec is excellent • Makes it painfully obvious when you’re violating SOLID
22. Software architecture
23. Software architecture • Your domain code is at the center of your application • Web framework for integrating your domain code with the web • CLI framework for giving your domain code a CLI
24. Domain code • Written like a library • We generally recommend Command-Query Separation • We also generally recommend using events • Commands and events are messages
25. Domain code • Take a DDD approach to modeling your domain • Analyze your problem domain, create a model • Entities, Value objects, Aggregates, Domain events, Services, Repositories and Factories • Event storming looks cool, but we’ve never had the opportunity to do it
26. Messages • Imagine you’re the emperor of Rome. You like to sit in your palace. • When your army has conquered new territory, you are passed a scroll with the details of the event • When you need to quash a rebellion to maintain pax romana, you send a scroll with your command to the governor
27. Messages • Messages differ mainly in intent • Events are informative in nature, and they are passed to anyone whom they concern • Commands are imperative in nature, and they are only passed to their respective command handler
28. –The Office “Look, it doesn't take a genius to know that any organization thrives when it has two leaders. Go ahead, name a country that doesn't have two presidents. A boat that sets sail without two captains. Where would Catholicism be without the popes?
29. Messages • Messages are just small PHP class instances that can be passed around • Immutability is king • Messages do not have return values
30. Messages • To handle a message, we use a message bus • Commands are handled by a command bus • Exactly one handler per command • Events are handled by an event bus • Zero or more event listeners
31. SimpleBus • Message bus library written by Matthias Noback • Messages and handlers are just your own PHP classes • Also supports asynchronous message handling
32. SimpleBus
33. SimpleBus
34. SimpleBus
35. Domain Code • Another interesting pattern is the Specification pattern • RulerZ • Under trial
36. Specification Pattern • All members who have the gold status • SELECT * FROM members WHERE status = ‘gold’
37. Specification Pattern • Not very object oriented • Ties your query builder to both your database engine and your database scheme • Imagine having to implement a rules engine
38. Specification Pattern
39. Specification Pattern
40. Web frameworks • Integrate your domain code into the web • A controller takes an HTTP request, returns an HTTP response • Thin glue to your domain • Your domain code does not have any dependencies on your web framework
41. Web frameworks • Modern frameworks are many things • In Symfony, the web framework is really only HttpKernel and HttpFoundation • Web related components (security, form) • Glue components (dependency injection) • Misc (yaml, ldap)
42. Frameworks • Depending on one of the miscellaneous components is fine if it makes sense. • In Symfony, we have the concept of a bundle, which integrates a library with the framework • Your domain code is a library
43. Dependency Injection • Do not use the Dependency Injection Container as a service locator.
44. Dependency Injection • I’m serious.
45. Dependency Injection • Separate your domain code and your bundle • Your domain code should know nothing of your DI container • Most of your bundle should know nothing of your DI container • Bundle extension and compiler passes mostly
46. Dependency Injection • Symfony controller base class is not a good role model • Luckily, it’s optional
47. Demo
48. Questions?
49. Contact • @drrotmos on Twitter • magnus@fervo.se • Want help? We’re a consultancy, so give me a call • https://www.fervo.se