1. Application generation Peter Bell SystemsForge Peter Bell SystemsForge Beyond Scaffolding

2. Overview Beyond Scaffolding A New Approach to Programming Key Concepts Anatomy of a Generator Software Product Lines Generating Web Applications

3. Let’s Start With Scaffolding Scaffolding is “free functionality” List, view, add, edit, delete Typically driven by DB schema Usually end up rewriting

4. Why Rewrite? Databases are dumb!... SSN is not just char(9) Form fields Advanced validation Display rules Business rules

5. A New Approach to Programming Language Oriented Programming “Building software around a set of Domain Specific Languages” - Martin Fowler Programmer as Language Designer

6. Language Oriented Programming OMG: Model Driven Architecture Microsoft: Software Factories Charles Simonyi: Intentional Programming JetBrains (IntelliJ): Meta Programming System MetaCase: MetaEdit EVERYONE is Doing It!!!

7. Language Oriented Programming Custom TagsUDFs CFCsAPIs YOU’re Already Doing It Property: Value FileXML Config File

8. API As Language Design... CODE... String = getDependentObjectList(ObjectName: String) Concept: getDependentObjectList Attribute: ObjectName

9. Language Oriented Programming Why do it?... Encapsulating Complexity (layered software) Key concepts...

10. Domain Specific Languages Limited form...... Specific domain Horizontal: - SQL - Reg-Ex - Objects - Notifications Vertical: - Newsletter - Shipping Rules - Insurance Quotes - Newspaper Workflows “Trade generality for expressiveness”

11. Three Types of Language Declaritive: What to do (requirements) Templating: Where to put (layout) Scripting: How to do (imperative)

12. Declaritive User @FullName: Name: Optional @Email: Email: Required @Password: Password: Required SELECT FullName FROM tbl_User Where UserID = 7

13. Templating #Title# $#Price#

14. Scripting For (Count = 1; Count lte listlen(ObjectDependencyList); Count=Count+1) { // Get current object name LoopObjectName = ListGetAt(ObjectDependencyList, Count); If (LoopObjectName NEQ "LightWire") { // Prepend it with ObjectName LoopObjectName=ListAppend(arguments.ObjectName,LoopObjectName,"|"); // Add it to the new object dependency list TempObjectDependencyList=ListAppend(TempObjectDependencyList,LoopObjectName) };

15. Three Types of Language Declaritive: Ideal for Reuse Templating: Simplify for designers Scripting: Use to implement

16. Abstract vs. Concrete grammar WHAT say vs. HOW say FirstName User @FirstName Boxes and Arrows

17. In-Language vs. External DSL In Language: CFC, UDF, Custom Tag Easy to create No validation Can use core language External: XML/custom file Store in database Harder to create Validation Can limit language

18. Types of Generation Passive Active Round trip Not much use Works great Not Required ->

19. Anatomy of a Generator Metadata Templates Iterator Orchestrator Extensions

20. Metadata Scripting XML Custom Syntax Databased

21. Templates Generating n-Getters: Template: > > Velocity - XSLT - CF Template Generate a File

22. Templates

23. Iterator One DAO per business object One template per screen In general: one file per instance of concept Possibly filter concepts Generate n-Files

24. Orchestrator Metadata (getObjectList) Template (ObjectDAO.cft) Iterator (Object: All) File name (#ObjectName#DAO.cfc) Generate m-Collections of n-Files

25. Extensions “Safe Code Snippets” Inheritance

26. Anatomy of a Generator Metadata Templates Iterator Orchestrator Extensions Generation NEQ Deployment

27. Software Product Lines Core Framework (scripts, DSLs, metadata) Feature Model Configurators

28. Generating Web Applications What is a website? Object Model+Interface Model

29. Object Model Objects: Attributes: Relationships Objects and Attributes: Content @LiveDate: Optional: Datetime: 1/1/2000 @KillDate: Optional: Datetime: 1/1/3000 @Status: Required: Status: approved Page: extends Content @Title: Required: Title Article: extends Content @Content: Optional: HTML Relationships: Page: Article: optional: multiple Article: Page: required: single

30. Object Model (2) Custom Data Types LiveDate @Transform: Date @Validate: IsDate @Field: DatePicker @Display: AsDate Status @Validate: IsDate @Field: Dropdown @List: StatusList Content @Transform: SafeHTML @Field: WYIWYG

31. Interface Model Screens: Actions: Steps Screens BaseList @Type=List @Paging = Yes @DefaultRecordsPerPage = 50 @RecordsPerPageList = 10,25,50,all ArticleAdminList extends BaseList @Type=List @AttributeList: Title,Status @OrderByAttributes: Title,Status @DefaultOrderBy: Title

32. Conclusions Programming as Language Design Horizontal and vertical DSLs Top down and and bottom up Generate everything: scripts, database, documentation, config XML, build scripts, etc. Layer software product line for higher levels of reuse Look out for CFGen, CF Template http://www.pbell.com Email: pbell@systemsforge.compbell@systemsforge.com