WHAT IF YOUR APPLICATION COULD SPEAK?

Domain-Specific Language concepts, applications and implementation. An introduction to Language-Driven Development.

Marcos Vinicius@bymarkone

Imagine you have a problem to solve …

SUPPLY CHAIN MANAGEMENT

The complexity of inter company documents exchange

THE NEEDS

Translate Documents

Transfer Documents

Was not satisfactory for this context - too much work!

Altova MapForce - the best solution we found

Document oriented data model

Set of rules that convert an layout to

another

A repository of identified layouts

Several helper functions to help

with the task

An idea

to solve

the problem

Will it work?

After three months - Huge architecture effort spent,

not a single functionality, people lost in system complexity

A language with the semantics of the Document Translation Domain that allowed us to succeed, and to be really faster

We decided to create a…

Domain-Specific

Language

FileTransfer

Banking

Contract Management

Financial

Accounting

Supply Chain

Lexical Analysis

Syntax

Semantics

Grammar

Alphabet

A new era arrived

BUSINESS LEVELHow The Language-Driven Approach Can Change Business

OTHER DSL

!

▫︎A DSL to query Document

▫︎A DSL to program inside Documents

▫︎A DSL to configure Rules for file transfer

▫︎A DSL to configure networks of Documents

▫︎A DSL to configure security and access

META-LANGUAGE

!

▫︎A language that defines a language

▫︎Define name of the objects and verbs of your language

▫︎Define adjective, if they are mandatory, their datatype

▫︎Allows you have feedback of language syntax in parsing

▫︎Validate a language semantically

▫︎ Provide auto-generated APIs documentation

▫︎ Provide information for client IDEs

LANGUAGE TEMPTING

!

▫︎A feature that allows you to simplify the language that the end user can access

!

!

!

!

!

▫︎Granular functionality and modularisation

▫︎On Demand combination to build complex operations

define User “bymarkone" with e-mail “bymarkone@tw.com“; create Account for “bymarkone”;

activate Account, User “bymarkone”; send confirmation to "bymarkone"

define and activate User "bymarkone"

becomes

BUSINESS SCRIPTING

!

▫︎When we have large amount of tasks

▫︎ E.g. Configuring a new account with N users

▫︎ E.g. Setting up a system

▫︎ E.g. Sending download instructions to several clients

▫︎ Speed in implementation of even complex systems

DEMOING

!

▫︎Build N scenarios for demoing you application

▫︎ End users can understand the language and play with scenarios

ANALYSIS LEVELLanguage Oriented Analysis

add User “Robespierre”; add User “Rosseau”; !“Rosseau” invites “Roberpierre”; “Robespierre" accept invite from “Rosseau" “Rosseau” create group “Vive la France!” with tag “Liberté, égalité, fraternité” “Robespierre" post in “Vive la France!”, message “Let's meet next 14th and kill the king!” !“Roberpierre" list friends; “Rosseau" add message "People who know little are usually great talkers, while men who know much say little”; !“Rosseau" add message “I am sorry to inform you all that our friend and compatriot Roberspierre was guillotined. This bloody revolution is changing out country at a very high price. ”

Let’s do a Social Network System

ARCHITECTURE LEVELLanguage Oriented Architecture

API'S

!

▫︎ REST API - A set of URL’s (names) and Actions

▫︎Must be expressive

▫︎ Limited - beyond crud, has only HTTP verbs

▫︎With a rich language is hard to draw an API that is as rich

▫︎ Expose and API (it can be rest) for language processing

USER EXPERIENCE - UX

!

▫︎ Should be build in top of the language

▫︎We don’t care how modern and visual is the design, as long as it talks the domain language

▫︎ E.g. SQL is a DSL on data query and manipulation - how many UI’s are built in top of that?

▫︎Will an editor with auto-complete and validation work?

TESTING

!

▫︎Unit, integration, component and contract test the application (independent of the language)

▫︎Add tests for language processing - parsing and interpreting

▫︎Add tests for language processing feedback

▫︎Add tests for domain and service executing through DSL

OVERALL ARCHITECTURE

!

▫︎UI Layer

▫︎Web Layer (REST)

▫︎ Language Processing Layer

▫︎Domain/Services Layer

▫︎ Infrastructure Layer

UI Layer

Web / Rest Layer

Language Processing

Domain Layer

Infrastructure Layer

From Martin Fowler’s DSL

PROCESS LEVEL

COMMUNICATION

!

▫︎ The DSL is the language of communication of business

▫︎Devs, QA, BA, PO, Business Specialist, even Stakeholders

▫︎Ubiquitous Language

▫︎ “Semantic Meetings” to understand and refine words of the language, and their meaning

DOMAIN-DRIVEN DESIGN

!

▫︎ Important to start the discussion about Domain meaning - Entities, Services, Aggregates, Value-Objects

▫︎Design and Domain are emergent - they are created/refactored with the development of the application

▫︎Create the DSL

▫︎Create the Semantic Model - connected to the DSL

▫︎ Semantic Model is different than the Domain Model - the first is a subset of the second.

PROGRAMMING LEVELThe fun of building a language

OVERALL OF LANGUAGE PROCESSING

Lexical Analysis Parsing Semantic

AnalysisText Tokens AST

Abstract Syntax

Tree

Code Generation

Semantic Model

grammar IML; !program : (functionDecl | stat | expr)+; functionDecl : type ID LP formalParams? RP block; formalParams : formalParam (COMMA formalParam)*; formalParam : type ID; type : (DOUBLEDECL | INTDECL | STRINGDECL); varDecl : type ID (EQUAL expr)? SEMICOLON ; block : LB stat* RB; assignment : expr EQUAL expr SEMICOLON; conditional : IF expr THEN stat (ELSE stat)?; returnstat : RETURN expr? SEMICOLON; stat : block | varDecl | conditional | returnstat | assignment | expr SEMICOLON ; expr : functionExpr // f() | arrayExpr // g[] | unaryOpExpr | expr binaryOp | idExpr | intExpr | stringExpr

BNF GRAMMARS

ANTLR

LANGUAGE LEVELExpanding horizons of our thought

Grammars

Alphabets

Languages

Syntactics

Semantics

Compilers

State Machines

Regular Languages

Context-Free Grammars

PHILOSOPHICAL LEVELLanguages and Thought

“Because language does not mimic the world, you can do things with it that are impossible under the law of physics. You are a god

in language. You can create. Destroy. Rearrange. Shove words around however you like. You can make up stories about things

that never happened to people who never existed. You can push a camel through the eye of a needle. It’s easy if ‘camel' and ‘needle’

are words.

In language, mortality does not tick relentlessly. You can conceive of yourself as alive forever. Or you can imagine yourself dead. And

then alive again. You can live, die, live, die, live, die, live.”

The First Word: The Search for the Origins of Language

Christine Kenneally

Imaginary

Virtual

Real

Understand the Power of Languages,

Domain-Specific Languages,

for your project, architecture and business

Language-Driven Development

Define a DSL that is going to represent the whole set of functionalities that your application communicates with the external world.

Build this DSL in top of your high-level language, this second will implement the more broad domain logic of your application.

Design your architecture, UX, ubiquitous language, meetings with business, testing, external APIs… in top of that DSL.

This DSL is going to be the language your application speaks

For questions or suggestions: !

Marcos Vinicius @bymarkone

github.com/bymarkone

THANK YOU