Linguistic Abstraction for the Web

Linguistic Abstraction for the Web Eelco Visser http://eelcovisser.org Mountain View June 8, 2011

MessagesLinguistic abstraction as software engineering tool Web languages can be improved

Software EngineeringProblem MachineDomain bridging the gap between problem domain and solution domain

High-Level LanguagesProblem HLL MachineDomain "A programming language is low level when its programs require attention to the irrelevant." Alan J. Perlis (1982) HLLs reduce gap

Domain-Speciﬁc LanguagesProblem DSL HLL MachineDomain domain-speciﬁc languages support more specialization

Software Language Design & Engineeringenable software engineers toeffectively design, implement, and apply domain-speciﬁc software languages

Research: Software Language Engineering Automatically derive efﬁcient,scalable, incremental compiler + usable IDE from high-level, declarativelanguage deﬁnition

The Spoofax Language Workbenchcreating full featured IDEs for domain-speciﬁc languages

Research: Software Language Design Systematically design domain- speciﬁc software languages with optimal tradeoff between expressivity,completeness, portability, coverage, and maintainability

Software Language Design Case Studies Mobl: client-side stateful web applicationsWebDSL: server-side restful web applications

http://webdsl.orgEelco Visser, Danny Groenewegen, et al.

Web Programmingbrowser server database web app

Web Programmingbrowser server databaseHTML, Java SQLJS, CSS code runs on server, browser, and database

Concerns in Web Programming❖ Persistent data ★ data integrity ★ search❖ User interface ★ data validation ★ styling, layout ★ navigation ★ actions❖ Access control

Separation of Concerns in Web ProgrammingExample❖ Data modeling ★ Java classes with JPA annotations❖ User interface ★ Java ServerFaces XML templates ★ Seam Java classes❖ Access control ★ Acegi conﬁguration/annotation

Problems in Web Programming❖ Lack of integration ★ no cross language/concern consistency checking ★ leads to late (detection of) failures❖ Low-level encoding ★ leads to boilerplate code

When Seam FailsWelcome #{user.name} Welcome #{user.nam}

When Rails Fails@post = Post.new(params[:get]) @post = Post.new(params[:post])

Late Failures in Web Applications Zef Hemel, Danny M. Groenewegen, Lennart C. L. Kats, Eelco Visser. Static consistency checking of web applications with WebDSL. Journal of Symbolic Computation, 46(2):150-182, 2011.

Separation of Concerns+ Linguistic Integration

WebDSL Example

Model-View Pattern

Modelentity Blog { key :: String (id) title :: String (name) posts -> Set<Post> (inverse=Post.blog)}entity Post { key :: String (id) title :: String (name, searchable) content :: WikiText (searchable) blog -> Blog created :: DateTime (default=now()) modified :: DateTime (default=now())}

Automatic PersistenceData Entity DBModel Classes SchemaWebDSL Java DBObject Object Records

Logicentity Blog { key :: String (id) title :: String (name) posts -> Set<Post> (inverse=Post.blog) function recentPosts(index: Int, n: Int): List<Post> { var i := max(1,index) - 1; return [p | p: Post in posts order by p.created desc limit n offset i*n].list(); } function newPost(): Post { var p := Post{ title := "No Title" blog := this }; p.key := p.id.toString(); return p; }}

Page Deﬁnitiondefine page blog(b: Blog, index: Int) { main(b){ for(p: Post in b.recentPosts(index,5)) { showPost(p) } }}define showPost(p: Post) { ... }define page post(p: Post) { ... }

Template Deﬁnitiondefine page blog(b: Blog, index: Int) { ... }define showPost(p: Post) { section{ header{ navigate post(p) { output(p.title) } } par{ output(p.content) } par{ output(p.created.format("MMMM d, yyyy")) } }}define page post(p: Post) { ... } Navigate = Deferred Page Call

Page Deﬁnitiondefine page blog(b: Blog, index: Int) { ... }define showPost(p: Post) { ... }define page post(p: Post) { main(p.blog){ showPost(p) navigate editpost(p) { "[Edit]" } }}

Forms & Data Bindingdefine page post(p: Post) { ... }define page editpost(p: Post) { action save() { return post(p); } main(p.blog){ form{ formEntry("Title"){ input(p.title) } formEntry("Content") { input(p.content) } formEntry("Posted") { input(p.created) } submit save() { "Save" } } }} (Look Ma, No Controller!)

Type-Directed Inputdefine page post(p: Post) { ... }define page editpost(p: Post) { action save() { return post(p); } main(p.blog){ form{ formEntry("Title"){ input(p.title) } formEntry("Content") { input(p.content) } formEntry("Posted") { input(p.created) } submit save() { "Save" } } }}

View Compositiondefine sidebar(b: Blog) { list{ listitem{ navigate blog(b,1) { "Home" } } listitem{ submitlink action{ return editpost(b.newPost()); } { "[New Post]" } } } section{ header{"Recent Posts"} output(b.recentPosts(1,10)) }}

Native Interfacedefine main(b: Blog) { includeCSS("style.css") <div id="outercontainer"> <div id="container"> <div id="sidebar">sidebar(b)</div> <div id="contents">elements</div> <div class="clear"> </div> </div> <div class="clear"> </div> </div>}

Integrated Development Environment short demo: consistency checking

WebDSL Languages Data Model Logic Templates (UI, Email, Service) Access Control Data Validation SearchCollaborative Filtering

http://www.mobl-lang.orgZef Hemel

Divergence in Mobile Platforms Objective-C Java J2ME/C++HTML/Javascript Java .NET Native Applications not Portable

Convergence in Mobile PlatformWebkit browser Webkit browserWebkit browser Webkit browser

The Universal Userinterface Engine

Mobile Web Architecture

Rich Applications Audio WebDatabases Full-screen supportLocation information (GPS) Offline support Canvas Accelerator support Multi-touch

Native Applications Address book Camera Compass File IO Notiﬁcations

Software Engineering with JavaScriptannotated HTML imperative Javascript MVC, No Integration, No Abstraction, Accidental Complexity

typed declarativeintegrated concise

Web Application with Touch

Portable Applications

Mobl Architecture

tipcalculator.moblapplication tipcalculatorimport mobl::ui::genericscreen root() { var amount = 20 var percentage = 10 header("Tip calculator") group { item { numField(amount, label="amount") } item { numField(percentage, label="percentage") } item { "$" label(Math.round(amount * (1 + percentage/100))) } } nl()}

Task Manager

Data Modelentity Task { name : String (searchable) done : Bool due : DateTime category : Category (inverse: tasks) tags : Collection<Tag> (inverse: tasks)}entity Category { name : String tasks : Collection<Task> (inverse: category)}entity Tag { name : String tasks : Collection<Task> (inverse: tags)} HTML5 Data Persistence

Logicentity Task { name : String (searchable) done : Bool due : DateTime category : Category (inverse: tasks) tags : Collection<Tag> (inverse: tasks) function postpone(days : Num) { this.due = DateTime.create( this.due.getFullYear(), this.due.getMonth(), this.due.getDate() + days); } function import(user : String, pw : String) { var tasksJSON = httpRequest("/export?user="+ user + "&pw=" + pw); foreach(t in tasksJSON) { add(Task.fromSelectJSON(t)); } }} statically typed: catch errors early

Reactive User Interfacesscreen root() { var phrase = "" header("Tasks") { button("Add", onclick={ addTask(); }) } searchBox(phrase) group { list(t in Task.search(phrase) limit 20){ item { checkBox(t.done, label=t.name) } } }}

Navigationscreen root() { var phrase = "" header("Tasks") { button("Add", onclick={ addTask(); }) } searchBox(phrase) group { list(t in Task.search(phrase) limit 20){ item { checkBox(t.done, label=t.name) } } }}

Navigationscreen root() { { addTask() var phrase = "" t = Task() header("Add") { header("Tasks") { button("Done", onclick={ button("Add", onclick={ addTask(); }) } add(t); searchBox(phrase) screen return; group { }) } list(t in Task.search(phrase) limit 20){ textField(t.name) item { datePicker(t.due) checkBox(t.done, label=t.name)} } } }}

Navigationscreen root() { var phrase = "" header("Tasks") { button("Add", onclick={ addTask(); }) } searchBox(phrase) group { list(t in Task.search(phrase) limit 20){ item { checkBox(t.done, label=t.name) } } }}

Continuationsscreen root() { button("Ask", onclick={ alert("Hello " + prompt("First name") + " " + prompt("Last name")); })}screen prompt(question : String) : String { var answer = "" header(question) { button("Done", onclick={ screen return answer; }) } textField(answer)}

User Interface Idiom: Tabcontrol tab1() { header("Tab 1") label("This is tab 1")}control tab2() { header("Tab 2") label("This is tab 2")}screen root() { tabSet([("One", tab1), ("Two", tab2)], defaultTab="One")}

Tab Set: Higher-Order Controlcontrol tabSet(tabs : [(String,Control)], activeTab : String) { list((tabName, tabControl) in tabs) { block(onclick={ activeTab = tabName; }, style=activeTab==tabName ? activeTabButton : inactiveTabButton) { label(tabName) } } list((tabName, tabControl) in tabs) { block(activeTab==tabName ? visibleTab : invisibleTab) { tabControl() } }} increase coverage: developers can create abstractions

User Interface Idiom: Master Detailcontrol taskItem(t : Task) { checkBox(t.done, label=t.name)}control taskDetail(t : Task) { textField(t.name) datePicker(t.due)}screen root() { header("Tasks") masterDetail(Task.all() order by due desc, taskItem, taskDetail)}

Master Detail: Higher-Order Controlcontrol masterDetail(items : Collection<?>, masterItem : Control1<?>,detail : Control1<?>) { group { list(it in items) { item(onclick={ detailScreen(it,detail); }) { masterItem(it) } } }}screen detailScreen(it : ?, detail : Control1<?>) { header("Detail") { backButton() } detail(it)}

Adaptive Layout

Mobl IDEstatic cross-concern consistency checking

DiscussionWebDSL vs Mobl crucial difference: navigation models why do we need both?

Linguistic Abstraction for the Web Linguistic abstraction: capture software knowledge in domain-speciﬁc languages http://spoofax.orgseparation of concerns + linguistic integration http://mobl-lang.org cross concern consistency checking http://webdsl.org early detection failures http://researchr.org Language workbench: DSL design and http://eelcovisser.org implementation with less effort than traditional language engineering http://researchr.org/search/publication/mobl+spoofax+webdsl

Linguistic Abstraction for the Web

by Eelco Visser on Jun 15, 2011

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Linguistic Abstraction for the Web — Presentation Transcript