Rampant Pragmatism Growth & Change at Starling Bank Dan Osborne - - PowerPoint PPT Presentation

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Rampant Pragmatism Growth & Change at Starling Bank Dan Osborne - - PowerPoint PPT Presentation

Dec 23, 2023 12 likes •696 views

Rampant Pragmatism Growth & Change at Starling Bank Dan Osborne - Web Technology Practice Lead Martin Dow - Engineering Lead for Core Banking Starling Bank 2014 - Founded UK mobile retail bank. Joint accounts, sole traders,

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Rampant Pragmatism

Growth & Change at Starling Bank

Dan Osborne - Web Technology Practice Lead Martin Dow - Engineering Lead for Core Banking

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  • 2014 - Founded
  • UK mobile retail bank.
  • Joint accounts, sole traders, limited companies.
  • Loans, Euro payments, foreign currency payments.
  • Internet Bank
  • 2019 - 1 million customers, £1 billion on deposit
  • 2020 - Europe? 2+ million customers? ...

Starling Bank

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  • Complexity: Essence vs Accident
  • A Relational Core
  • The Rest of the System
  • Our Web Stack
  • Our Ledger
  • Starling’s Engineering Principles

Agenda

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  • Complexity: Essence vs Accident
  • A Relational Core
  • The Rest of the System
  • Our Web Stack
  • Our Ledger
  • Starling’s Engineering Principles

Agenda

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No Silver Bullet Essence and Accident in Sofuware Engineering

Frederick P. Brooks, Jr. - The Mythical Man-Month

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“The fashioning of the complex conceptual structures that compose the abstract sofuware entity”

Essential Tasks

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“The representation of these abstract entities in programming languages and the mapping of these into machine languages within space and speed constraints.”

Accidental Tasks

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Spectrum of Complexity

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  • Complexity: Essence vs Accident
  • A Relational Core
  • The Rest of the System
  • Our Web Stack
  • Our Ledger
  • Starling’s Engineering Principles

Agenda

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“I don’t care how much you really love the syntax of your favourite programming language, it’s inferior to data in every way”

Rich Hickey (referencing Gerald Sussman)

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Essential Complexity Data Modelling as System Design

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Essential Complexity & Data Modelling

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Flex the Model

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Access Path Independence Relational Modelling

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Postgres

  • SQL: Access path independence
  • Constraints: A declarative barrier
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  • Complexity: Essence vs Accident
  • A Relational Core
  • The Rest of the System
  • Our Web Stack
  • Our Ledger
  • Starling’s Engineering Principles

Agenda

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Spectrum of Complexity

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Not a System Yet

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Out of the Tar Pit

What not How

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… you use Java?! But hang on...

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FRP System Components

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  • Avoid
  • Separate
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  • Avoid
  • Separate
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Observers & Feeders

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  • Complexity: Essence vs Accident
  • A Relational Core
  • Functional Relational Programming
  • Our Web Stack
  • Our Ledger
  • Starling’s Engineering Principles

Agenda

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React

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P R O P S

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STATE

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“... provide a much clearer mapping between your ideas about how the program works and the code you actually write.”

Peter Seibel – Practical Common Lisp, 2005

Functional Programs

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Redux

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Redux

CHANGE STATE HERE

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Web Development

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Web Development … is FRP?!

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  • Complexity: Essence vs Accident
  • A Relational Core
  • Functional Relational Programming
  • Our Web Stack
  • Our Ledger
  • Starling’s Engineering Principles

Agenda

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A Bank is an Accounting Machine

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Detailed & Diverse to Unified & Generic

A Bank is an Accounting Machine

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Denormalisation & Projection of Essential Data

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Denormalised Postings

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Separate Services?

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Self Contained Systems

  • Reduce blast radius
  • Avoid distributed monolith
  • Minimise synchronous calls
  • Each service has its own database
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Splituing the (Relational) Core

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  • Each system as event source
  • Database queues

Pushing Data Around

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  • Kafka?
  • Postgres Logical Replication?

Pushing Data Around

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  • Complexity: Essence vs Accident
  • A Relational Core
  • Functional Relational Programming
  • Our Web Stack
  • Our Ledger
  • Starling’s Engineering Principles

Agenda

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Software Engineering The Art of Compromise

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Pragmatism Moving Deliberately

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Bets

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Bets

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Bets

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Bets

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Bets + Principles = Architecture

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Optimise & Empower Bets + Principles = Architecture

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Understandability Bets + Principles = Architecture

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Simplicity & Consistency Bets + Principles = Architecture

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Rampant Pragmatism Change & Growth at Starling Bank

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“Most startups (and big companies) don’t need the tech stack they have.”

Vicki Boykis “You don’t need Kafka. Really.” Normcore Tech Newsletter

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Thank you!

https:/ /developer.starlingbank.com https:/ /www.starlingbank.com/careers/engineering/

@dtpo @martin_dow @StarlingDev

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  • No Silver Bullet -

https:/ /www.researchgate.net/publication/2204771 27_No_Silver_Bullet_Essence_and_Accidents_of_So ftware_Engineering

  • A Relational Model for Large Shared Data Banks -

https:/ /www.semanticscholar.org/paper/A-Relation al-Model-for-Large-Shared-Data-Banks-Codd/c4bd 2f89039031f09b9ddec07e6d456b0d08aab4

  • Out of the Tar Pit -

https:/ /www.semanticscholar.org/paper/Out-of-the

  • Tar-Pit-Moseley-Marks/41dc590506528e9f9d7650c

235b718014836a39d

  • Simple Made Easy -

https:/ /www.infoq.com/presentations/Simple-Made

  • Easy-QCon-London-2012/
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  • Object Oriented Software Construction -

https:/ /www.semanticscholar.org/paper/Object-Ori ented-Software-Construction-Meyer/5f0e007b600d 595b9c75cf3949d29b6ae21eed63

  • Mythical Man Month -

https:/ /www.bookdepository.com/Mythical-Man-M

  • nth-Frederick-P-Brooks-Jr/9780201835953
  • Practical Common Lisp -

https:/ /www.bookdepository.com/Practical-Commo n-Lisp-Peter-Seibel/9781430211617

  • Applied Mathematics for Database Professionals

https://www.apress.com/gp/book/9781590597453