Domain Specific Languages: a practical view

1. Domain Specific Languages: a practical view Leandro Marques do Nascimento Ph.D. Candidate at UFPE lmn2@cin.ufpe.br

2. Agenda • Introduction • Concepts • Examples • Types of DSLs • Advantages and disadvantages of using DSLs • Building a new Domain-Specific Language • Development phases • Understanding DSLs in details • Tools for creating DSLs • Xtext demo • What community has done so far

3. Introduction • DSLs offer substantial gains in expressiveness and ease of use compared with general-purpose programming languages in their domain of application [1]. • Problems • DSL development is hard, requiring both domain knowledge and language development expertise. Few people have both [1]. • The decision to develop a DSL is often postponed indefinitely, if considered at all, and most DSLs never get beyond the application library stage. Domain-specific languages (DSLs) are languages tailored to a specific application domain.

4. Examples of DSLs • In addition to Excel, a natural example of DSL: • AutoCAD for architectural design • ProEngineer for mechanical modeling • Verilog for hardware description • Mathematica for symbolic computing.

5. More examples of DSLs [2] • Language level is related to productivity

6. Types of DSLs [3] • Textual DSLs • Textual representation of a language that can be directly (or indirectly) transformed into executable code • Embedded DSLs • Mix between General Purpose Languages (GPLs) and Textual DSLs. Usually well know as application libraries (frameworks) • Visual DSLs (or graphical) • Based on visually representing a system a on incremental transformations of those visual models into executable code • Synonym for Model Driven * (MDD, MDA, MDSE, etc.) • Other types • External / Internal

7. DSLs: The good [4] • Targeted abstractions mean DSL programs express important information & hide details • “You can really see what we’re talking about” • DSLs can dramatically shorten the path between a specification and an implementation • Programs are shorter, easy do audit, maintain • Enormous productivity increase • From declarative abstractions, we can generate multiple artifacts: • Parser, printer, XML transaction, statistical analyzes • Compiler can ensure properties of programs: • Parser will return meta-data that describes errors

8. DSLs: The bad and the ugly [4] • Challenge of routine features • Include in DSL: replicate a lot of effort! • Borrow from ‘host’ language: have to process host language code • Lack of tools • DSLs often lack debuggers, profilers, IDE support, etc., because building them is labor intensive • Reluctant customers • Learning new languages is hard • Poor documentation and training on new DSLs • Limited knowledge and expertise on how to perform domain analysis

9. DSLs: the main goal • Gains in expressiveness and ease of use • The future is end-user programming

10. Caught much attention from both Academia and Industry • IEEE Transactions on Software Engineering (Vol. 35, No. 6) • Special Section on Software Language Engineering • The “Physics” of Notations: Toward a Scientific Basis for Constructing Visual Notations in Software EngineeringDaniel L. Moodyhttp://doi.ieeecomputersociety.org/10.1109/TSE.2009.67 • Engineering of Framework-Specific Modeling LanguagesMichałAntkiewicz, Krzysztof Czarnecki, Matthew Stephanhttp://doi.ieeecomputersociety.org/10.1109/TSE.2009.30 • Many different workshops, conferences and symposiums on MD* and DSLs

11. Building a new Domain-Specific Language First, you should understand DSLs in details

12. Building a new Domain-Specific Language • DSL development phases [1] • Decision • Decision in favor of a new DSL • Analysis • Domain knowledge is gathered. • Design • Relationship between the DSL and existing languages • The formal nature of the design description • Implementation • Interpreter/Compiler/Application Generators • Deployment • Started using the new DSL for building up new apps

13. Understanding DSLs in details - DSL classification [5] • Notation FODA

14. DSL classification [5]

15. DSL classification [5]

16. DSL classification [5]

17. DSL classification [5]

18. DSL Tools with textual modeling [6] • Xtext • TEF (Textual Editing Framework) • TCS (Textual Concrete Syntax) • EMFText • JetBrains MPS • MontiCore, CodeWorker, IMP • DSL2JDT, ETMOP, CAL

19. DSL Tools with textual modeling [6] • TMF Xtext (predessoroAWXtext) • http://xtext.org • http://wiki.eclipse.org/TMF • TEF Textual Editing Framework • http://www2.informatik.hu-berlin.de/sam/meta-tools/tef • http://developer.berlios.de/projects/tef/ • TCS Textual Concrete Syntax • http://wiki.eclipse.org/index.php/TCS • http://www.sciences.univ-nantes.fr/lina/atl/www/ • EMFText • http://emftext.org • http://st.inf.tu-dresden.de/reuseware/index.php/EMFText

20. DSL Tools with textual modeling [6] • JetBrains MPS • http://www.jetbrains.com/mps • Konstantin Solomatov • MontiCore • http://www.monticore.de • RWTH Aachen, Academic • CodeWorker • http://www.codeworker.org/ • Cedric Lemaire • IMP • http://eclipse-imp.sourceforge.net/ • Robert M. Fuhrer

21. DSL Example – Chess Game Using the Chess game to understand DSL construction

26. Xtext – Language Development Framework www.eclipse.org/Xtext/

27. Create a Language • Define the grammar • Add static analysis • Provide quickfixes • Implement an Interpreter

28. Grammar (Simple Arithmetics) • Grammar describes how models can be parsed Module: 'module' name=ID (imports+=Import)* (statements+=Statement)*; Statement: Definition | Evaluation; Definition: 'def' name=ID ('(' args+=DeclaredParameter (',' args+=DeclaredParameter)* ')')? ':' expr=Expression ';'; DeclaredParameter: name=ID; Evaluation: expression=Expression ';'; Grammar Model moduleSimpleArithmetics defboxVolume(l,w,h) : l*w*h; defcubeVolume(l) : boxVolume(l,l,l);

29. Chess Example - Grammar Game: "White:"whitePlayer=STRING "Black:"blackPlayer=STRING (moves+=Move)+; Move: AlgebraicMove | SpokenMove; AlgebraicMove: (piece=Piece)? source=Square (captures?='x'|'-') dest=Square; SpokenMove: piece=Piece 'at' source=Square (captures?='captures'capturedPiece=Piece 'at' | 'moves to') dest=Square; terminal Square: ('a'..'h')('1'..'8'); enum Piece: pawn = 'P' | pawn = 'pawn' | knight = 'N' | knight = 'knight' | bishop = 'B' | bishop = 'bishop' | rook = 'R' | rook = 'rook' | queen = 'Q' | queen = 'queen' | king = 'K' | king = 'king';

30. Chess Example - Model White: "Mayfield" Black: "Trinks“ pawn at e2 moves to e4 pawn at f7 moves to g5 K b1 - c3 f7 - f5 queen at d1 moves to h5 // 1-0

31. You can create a new view for your brand new language

32. Community • http://www.eclipse.org/Xtext/community/ • APPlause - Open source tool chain to produce native apps for different devices such as Android, iPhoneand. HeikoBehrens, Peter Friese, et al • Aranea - Messaging and infrastructure layer that uses Xtext for generating the message and support classes. Patrick Ruckstuhl • ARText(part of Artop) - ARText, a textual language for the specification of AUTOSAR systems. See the verycoolscreencasts. Sebastian Benz, Dana Wong

33. WebDSL [7] application minimalac entity User { name :: String password :: Secret } init{ var u := User{ name := "1" password := ("1" as Secret).digest() }; u.save(); } define page root(){ authentication() " " navigate protectedPage() { "go" } } define page protectedPage(){ "access granted" } principal is User with credentials name, password access control rules rule page root(){true} rule page protectedPage(){loggedIn()}

34. References • M. Mernik, J. Heering, and A. Sloane, “When and how to develop domain-specific languages,” ACM Computing Surveys (CSUR), vol. Vo.37 N.4, 2005, pp. 316-344. • JONES, C. 1996. SPR Programming Languages Table Release 8.2, http://www.theadvisors.com/ langcomparison.htm. (Accessed April 2005). Later release not available at publication. • M. Völter, “MD*/DSL Best Practices Update March 2011,” 2011, Available at http://voelter.de/data/pub/DSLBestPractices-2011Update.pdf, Accessed in March 2011. • J. Gray, K. Fisher, C. Consel, G. Karsai, M. Mernik, and J.-P. Tolvanen, “Panel - DSLs: The Good, the Bad, and the Ugly,” OOPSLA ’08: Companion to the 23rd annual ACM SIGPLAN conference on Object-oriented programming, systems, languages, and applications, 2008, Available at http://www.infoq.com/presentations/Truth-about-DSL, Accessed in March 2011. • B. Langlois, C.E. Jitia, and E. Jouenne, “Dsl classification,” OOPSLA 7th Workshop on Domain Specific Modeling, Citeseer, 2007. • Bernhard Merkle, “Textual Modeling Tools: Overview and Penalty Shoot-out ”, EclipseCON 2010, Available at www.infoq.com/presentations/Textual-Modeling-Tools, Accessed in March 2011. • WebDSL. http://webdsl.org/, Accessed in March 2011.

35. Questions? “If you can't make it good, at least make it look good.”Bill Gates • Domain Specific Languages: a practical view • Leandro Marques do Nascimento • Ph.D. Candidate at UFPE • lmn2@cin.ufpe.br