The JSON Architecture

An architecture pattern fordata driven functional programming

About MeConstantin Dumitrescu, find me as @dumconstantin on

Ask me about: JS, FP, Docker, Automating things, Development Tools, Radical Management

Projects: ramda-loader, json-patch-utils, baobab-jsoneditor

Presentations so far:

- The Philosophy and Practice of the Pure Function / 5 Feb, Cluj

- The JSON Architecture / 11 May, Bucharest :)

The JSON ArchitectureAn architecture pattern for data driven functional

programming - what it is, how did it come about, benefits?

Overview

Part 1. Data Transformations

Data Transformation- The single purpose of computer programs is to move

letters and numbers around- Why should the computer know what “this” is?- Unfortunately for them, data transformations should be

data-less- OOP is when data and transformations are joined in

marriage but always argue about separating - it’s painful, tedious and consumes a lot of resources

Pure Functions

Pure Functions- Are like atoms (“that which cannot be split”)- Probably the most boring thing in the universe- Always prefer curry-flavored functions- Pure functions know about the entropy of the input data- Can eliminate racism between programmers- Have random powers! (like Quickcheck)- Are reversible if the input types and output types align- Compose pure functions!

Observables & Streams

Observables & Streams

*from RX Docs

Observables & Streams- ... are the combination of CPS(continuation-passing

style), Events, Promises, Futures and Channels- An Observable is an Array with wristwatches instead of

commas:- Observables are like springs that create a stream- Flowing data is immutable- Now is not the time for errors, catch them later- Time stops when we stream - OMG! Thinking in 5 dimensions- Streams Pointfree- Compose streams!

Part 2. Persistent Data Tree

*from Redux Docs

Persistent Data Tree- Avoids cyclic dependencies between data, one of the by-

product of OOP in Time Driven systems- Data trees hold the absolute truth!- The connection between the data nodes are declared in a

single place (the data tree) instead of a myriad of objects

- The flow of data is obvious and unidirectional- The state is copied through reference, no memory leaks!- Same steps, same state - beat that OOP!

Essential State

Essential State- Like essential amino acids, comes from outside the system- Like collection items, you and label them

precisely. Also, box them and keep them safe!- Never use Arrays!- ?!Has no meaning whatsoever for the program, simply put,

it’s just letters and numbers- The Actors of the Business Domain create the essentials- Should be identical in shape and color on the Backend, on

the Frontend, in the Database and everywhere- Keep the essentials, normalize somewhere else

Derived and Accidental State

Derived and Accidental State- Derived state is the combination and transformation of

essential state- Accidental state is what happens when you don’t live in

an ideal world and when you need to keep a journal- The Derived state controls the program. Demonstration:

a) The program is controlled by “If Statements” decisions b) Decisions are derived from the truth d) The truth is the essential state e) “If Statements” use derived states, thus The Derived state controls the Program

- Remember, you can always derive a derived a derived state, so compose the derived state!

Cursors

Cursors- Use them to see from far away- Kinda like Channels (CSP Communicating Sequential

Processes)- You don’t care when something happens, but you’re looking

anyway- Work on Essential, Derived and Accidental states- Deliver immutable data- Use them with streams!- Compose cursors!

Dynamic Nodes

Dynamic Nodes- Suprise! A dynamic node outputs derived state- They sit in trees!- Cursors + Pure functions = a dynamic node- Lazy, never do processing unless requested- Use events to signal updates- Fun fact! Most cursors in your application will watch a

dynamic node- Compose dynamic nodes!

Part 3. Effects

Effects & Side Effects- Effects are the reason you wrote the program in the first

place- A side effect is: “any unintentional and detrimental

consequence”, e.g. an infinite loop!- An effect begins where the system ends and the outside

world begins- Mutating state is not a side effect, that’s just an

intentional bad design- Any output is an effect: 42 - what was the question?- Effects should be declared in a declarative way

Part 5.

The Overview once again

JSON Data & JSON Schema{ "$schema": "http://json-schema.org/draft-04/schema#", "type": "object", "properties": { "user": { "type": "object", "properties": { "name": { "type": "string" }, "email": { "type": "string", "pattern": "^\S+@\S+$" } }, "required": [ "name", "email" ] } }, "required": [ "user" ]}

{ "user": { "name": "John Doe", "email": "john@doe.com" }}

JSON Patch & JSON Pointer

let patch = [ {"op": "replace", "path": "/user/name", "value": "Jane Roe"}, {"op": "add", "path": "/user/address", "value": "51 Street"}, {"op": "test", "path": "/user/id", "value": 23}]

let data = { "user": { "name": "John Doe", "id": 23 } }

let data = { "user": { "name": "Jane Roe", "address": "51 Street", "id": 23 } }

Part 6: Demo Time

Opportunities & Benefits- Real separation of concerns:

1) Controller: How it happens 2) Model: That Thing that something happens on3) (Effects) View: What the world sees

- Pointfree = Stop writing code! = 1000% increase in stability and whatever is bugging you...

- Portability!!!! Take your code from one language to the next with minor syntax changes!

- !!! 5 minute project handover !!!- Open sourced all the way!

Opportunities & Benefits - Reuse everything between projects!- Bulletproof testing in isolation- Client stack traces no longer needed - just gimme the

state.json file!- When developing the Effects you don’t need data

transformations! Just modify the state tree as you please- Democratising Software Architecture- Focus on the business domain rather than on application

bugs

What the management needs to see- Better productivity = x2, x3, x4 more $$$- Better quality (SLA anyone?) = x2, x3, x4 more $$$- Appealing to investors - long term software without code

decay or legacy code issues ($$$)- Hassle-free project handover internally or by third party- Learn once - use everywhere - interoperability between

developers & technologies- Decrease lifecycle costs of software products $$$

And finally,The JSON Architecture is a postulate for making the life of developer’s happier, less stressful and more fun so that they can start contributing, and giving back, to what really matters:

“The goal of programming is to act as a bridge to

reconnect us, reinventing society and making a

true democracy.”* anonymous quote from the net

Thank You very much!I hoped for a Jerry Seinfeld and Morgan Freeman combo...

But, if that didn’t happen, you can reach out and I’ll answer any questions:

dumconstantin@gmail.com

And @dumconstantin on twitter/github/etc