What if-your-application-could-speak, by Marcos Silveira

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Imagine a team developing to a specific business domain. We use languages to communicate with the client, company and within the team. We also use programming languages to develop the software. And still, we want our code to express, no only a correct syntax for that language, but the knowledge of the business domain in which we are developing.
What if it was possible to capture the business meaning and transforme it into a language?
This talk is about DSLs, it's architecture, business use, and also how to implement and test them.

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What if-your-application-could-speak, by Marcos Silveira

  1. 1. WHAT IF YOUR APPLICATION COULD SPEAK? Domain-Specific Language concepts, applications and implementation. An introduction to Language-Driven Development. Marcos Vinicius @bymarkone
  2. 2. Imagine you have a problem to solve …
  3. 3. SUPPLY CHAIN MANAGEMENT The complexity of inter company documents exchange
  4. 4. THE NEEDS Translate Documents Transfer Documents
  5. 5. Was not satisfactory for this context - too much work! Altova MapForce - the best solution we found
  6. 6. 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
  7. 7. Will it work? After three months - Huge architecture effort spent, not a single functionality, people lost in system complexity
  8. 8. 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…
  9. 9. Domain- Specific Language FileTransfer Banking Contract Management Financial Accounting Supply Chain Lexical Analysis Syntax Semantics Grammar Alphabet
  10. 10. A new era arrived
  11. 11. BUSINESS LEVEL How The Language-Driven Approach Can Change Business
  12. 12. 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
  13. 13. 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
  14. 14. 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
  15. 15. 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
  16. 16. DEMOING ! ▫︎Build N scenarios for demoing you application ▫︎End users can understand the language and play with scenarios
  17. 17. ANALYSIS LEVEL Language Oriented Analysis
  18. 18. 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
  19. 19. ARCHITECTURE LEVEL Language Oriented Architecture
  20. 20. 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
  21. 21. 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?
  22. 22. 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
  23. 23. 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
  24. 24. PROCESS LEVEL
  25. 25. 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
  26. 26. 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.
  27. 27. PROGRAMMING LEVEL The fun of building a language
  28. 28. OVERALL OF LANGUAGE PROCESSING Lexical Analysis Parsing Semantic Analysis Text Tokens AST Abstract Syntax Tree Code Generation Semantic
 Model
  29. 29. 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 BNF GRAMMARS
  30. 30. ANTLR
  31. 31. LANGUAGE LEVEL Expanding horizons of our thought
  32. 32. Grammars Alphabets Languages Syntactics Semantics Compilers State Machines Regular Languages Context-Free Grammars
  33. 33. PHILOSOPHICAL LEVEL Languages and Thought
  34. 34. “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
  35. 35. Imaginary Virtual Real
  36. 36. Understand the Power of Languages, Domain-Specific Languages, for your project, architecture and business
  37. 37. 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
  38. 38. For questions or suggestions: ! Marcos Vinicius @bymarkone github.com/bymarkone THANK YOU

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