The JSON architecture

TheJSONArchitecture
An architecture pattern for
data driven functional programming

AboutMe
Constantin 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 :)

TheJSONArchitecture
An architecture pattern for data driven functional
programming - what it is, how did it come about, benefits?

DataTransformation
- 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

PureFunctions
- 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
*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!

Part2.PersistentDataTree
*from Redux Docs

PersistentDataTree
- 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!

EssentialState
- 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

DerivedandAccidentalState
- 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
- 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!

DynamicNodes
- 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!

Effects&SideEffects
- 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

JSONData&JSONSchema {
"$schema": "http://json-schema.org/draft-04/schema#",
"type": "object",
"properties": {
"user": {
"type": "object",
"properties": {
"name": {
"type": "string"
},
"email": {
"type": "string",
"pattern": "^S+@S+$"
}
},
"required": [
"name",
"email"
]
}
},
"required": [
"user"
]
}
{
"user": {
"name": "John Doe",
"email": "john@doe.com"
}
}

JSONPatch&JSONPointer
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 } }

Opportunities&Benefits
- Real separation of concerns:
1) Controller: How it happens
2) Model: That Thing that something happens on
3) (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

Whatthemanagementneedstosee
- 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 ($$$)
- Hassle-free project handover internally or by third party
- Learn once - use everywhere - interoperability between
developers & technologies
- Decrease lifecycle costs of software products $$$

Andfinally,
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

ThankYouverymuch!
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

The JSON architecture

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