mobl - model-driven engineering lecture

http://www.mobl-lang.org

Zef Hemel

Objective-C Java J2ME/C++

HTML/Javascript Java .NET

Webkit browser Webkit browser J2ME/C++

Webkit browser Webkit browser .NET

WebDatabases

Location information
(GPS)

WebDatabases

(GPS)

Canvas

WebDatabases

(GPS)

Canvas

Multi-touch

WebDatabases

(GPS)
Ofﬂine support
Canvas

Multi-touch

WebDatabases
Full-screen support
(GPS)
Ofﬂine support
Canvas

Multi-touch

WebDatabases
Full-screen support
(GPS)
Ofﬂine support
Canvas
Accelerator support
Multi-touch

Address book
Camera
Compass

Address book
Camera
Compass
File IO

Address book
Camera
Compass
File IO
Audio

Address book
Camera
Compass
File IO
Audio
Notiﬁcations

today
1. language

2. behind the scenes

user interface

styling

data modeling

scripting

web services

ui syntax

screen name(farg*) : ReturnType? {
screenelem*
}

control name(farg*) {
screenelem*
}

screen root() {
...
}

screen promptString(q : String) : String {
...
}

screen root() {
...
}

screen promptString(q : String) : String {
...
}

control button(s : String,
onclick : Callback = {}) {
...
}

control calls

variable declarations

control structures

inline HTML

script blocks

control calls
button("Click me")

control calls
button("Click me")

button("Click me", {
alert("Click!");
})

control calls
button("Click me")

button("Click me", {
alert("Click!");
})

button("Click me", onclick={
alert("Click!");
})

control calls with body

group() {
item() { "Item 1" }
item() { "Item 2" }
}

control calls with body

group {
item { "Item 1" }
item { "Item 2" }
}


var b = true


var b = true
var b : Bool = true


var b = true
var b : Bool = true
var newTask = Task()


var b = true
var b : Bool = true
var newTask = Task()
var newTask : Task = Task()

when

var b = true

checkBox(b)

when(b) {
label("Yep")
} else {
label("Nope")
}

list

var nums = [1, 2, 3]

group {
list(n in nums) {
item { label(n) }
}
}

inline HTML

<img src="img/icon.png"/>

inline HTML

<img src="img/icon.png"/>

<div class=selected ? selectedStyle
: notSelectedStyle>
...
</div>

script blocks
avoid if possible

var n = -1
script {
n = Math.sqrt(9);
}

style bigAndBlue {
color: blue;
font-size: 40px;
}

Style
style bigAndBlue {
color: blue;
font-size: 40px;
}

control block(style : Style) {
...
}

block(bigAndBlueStyle) {
label("I am big and blue!");
}

style $baseColor = rgb(100, 100, 100)

style myStyle {
color: rgb($baseColor.r+10,
$baseColor.g+50,
$baseColor.b-20);
font-size: 20px;
}

style mixin borderRadiusMixin($radius) {
-moz-border-radius: $radius;
-webkit-border-radius: $radius;
border-radius: $radius;
}

style mixin borderRadiusMixin($radius) {
-moz-border-radius: $radius;
-webkit-border-radius: $radius;
border-radius: $radius;
}

style myStyle {
color: $baseColor;
borderRadiusMixin(10px);
}

entity Task {
name : String (searchable)
done : Bool
tags : Collection<Tag> (inverse: tasks)
}

entity Tag {
tasks : Collection<Task> (inverse: tags)
}

var newTask = Task(name="New task");
newTask.done = false;
add(newTask);

Collection<Task>
var doneTasks = Task.all()

Collection<Task>
.filter("done", "=", true)
.order("date", false)
.limit(10);

Collection<Task>
var tagDoneTasks = tag.tasks
.limit(10);

Collection<Task>
where done == true
order by date desc
limit 10;

Collection<Task>
var tagDoneTasks = tag.tasks
where done == true
order by date desc
limit 10;

Collection<Task>
var searchTasks = Task.search("task")
where done == true
limit 10;

screen root() {
header("Tasks")
group {
list(t in Task.all() order by date desc) {
item { label(t.name) }
}
}
}

script in ui

label("Total tasks: " + Task.all().count())

script in ui

label("Total tasks: " + Task.all().count())

button("Click me", onclick={
alert("You clicked me!");
})

var n = 7;
var n2 = Math.round(n/2);

if(n2 > 3) {
alert("More than three!");
} else {
alert("Less than three!");
}

type inference
var n = 7;
var n2 = Math.round(n/2);

if(n2 > 3) {
alert("More than three!");
} else {
alert("Less than three!");
}

var done = 0;
foreach(t in Task.all()) {
if(t.done) {
done = done + 1;
}
}

var done = 0;
if(t.done) {
done = done + 1;
}
}

var done = (Task.all()
where done == true)
.count();

function sqr(n : Num) : Num {
return n * n;
}

service SomeService {
resource tasks() : JSON {
uri = "/tasks"
}

resource search(query : String) : JSON {
uri = "/search?q=" + escape(query)
}
}

ajax same-source restriction

service Twitter {
resource trends() : JSON {
uri = "/_proxy/api.twitter.com/1/trends.json"
}

resource search(query : String) : JSON {
uri = "/_proxy/search.twitter.com/search.json?q="
+ escape(query)
}
}

http://api.twitter.com/1/trends.json

{"trends":
[{"url":"http://search.twitter.com/search?q=...",
"name":"#ihaveadream"},
{"url":"http://search.twitter.com/search?q=...",
"name":"#mlkday"}
...
]
}

type Trend {
name : String
url : String
}

function trendsMapper(json : JSON) : [Trend] {
return json.trends;
}

resource trends() : JSON {
uri = "/_proxy/api.twitter.com/1/trends.json"
mapper = trendsMapper
}

screen root() {
var trends = Twitter.trends()

header("Twitter trends")
group {
list(topic in trends) {
item {
label(topic.name)
}
}
}
}

limitations

slower than native

no native UI

not great for games

goals

portability

completeness

coverage

goals

portability web

completeness

coverage

goals

portability web

completeness 100% code gen

coverage

roadmap
1. design core abstractions + native interface

roadmap

2. enable user land abstractions

roadmap


3a. support successful ULAs with syntax

roadmap



3b. support common native interface cases
with core abstractions

core abstraction:

synchronous programming

no more asynchronous
spaghetti code

synchronous programming

var results = Task.all().list();
for(var i = 0; i < results.length; i++) {
alert(results[i].name);
}

render page

time
query database
and process
results

...

render page

time
query database
browser freeze and process
results

...

render page

send query

time
...

process query
result

...

asynchronous programming

Task.all.list(function(results) {
for(var i = 0; i < results.length; i++) {
alert(results[i].name);
}
});
...

Task.all().list(function(results) {
alert("Hello, ");
});
alert("world!");

alert("Hello, ");
}); breaks sequential
alert("world!");
execution assumption

// make changes
...
persistence.flush(function() {
alert("Changes saved!");
});
});

continuation-passing style
transformation

function displayLocationAndReturn() : Coordinates {
var position = mobl::location::getPosition();
log("Lat: " + position.latitude);
log("Long: " + position.longitude);
return position;
}

core abstraction:

data binding

no more copying data from and
to UI

screen root() {
var n = 8
label(n * n)
button("Inc", onclick={
n = n + 1;
})
}

var n = 8

var n = ref(8);

Observable
- set(value)
- get()
- addEventListener(eventType, callback)

label(n * n)

var node = $("<span>");
node.text(n.get() * n.get());
n.addEventListener("change", function() {
node.text(n.get() * n.get());
});
root.append(node);

button("Inc", onclick={
n = n + 1;
})

var node = $("<button ...>");
node.text("Inc");
node.click(function() {
n.set(n.get() + 1);
});
root.append(node);

core abstraction:

data modeling & query

no more SQL

uses persistence.js
http://persistencejs.org

entity Task {
description : String (searchable)
done : Bool
date : DateTime
}

var Task = persistence.define('Task', {
name: 'VARCHAR(255)',
description: 'VARCHAR(255)',
done: 'BOOL',
date: 'DATE'
});

Task.textIndex('description');
Task.textIndex('name');

alert(t.name);
}

Task.all().forEach(function(t) {
alert(t.name);
});

foreach(t in Task.all() where done == true) {
alert(t.name);
}

Task.all().filter("done", "=", true).forEach(function(t) {
alert(t.name);
});

external entity MyEntity

external type MyType

external control contextMenu()

external screen specialScreen()

external sync function add(o : Object) : void

external style myStyle

external sync function add(o : Object) : void

<javascript>
__ns.add = function(o) {
persistence.add(o);
};
</javascript>

load styles/default.css
load js/persistence.js

where do abstractions
come from?

come from?

domain

come from?

domain

experience

control

screen

domain

control

screen entity

domain

control

screen entity

domain

event

control

screen entity

domain

event web service

other DSLs

experience

other DSLs

experience

programming
paradigms

other DSLs annoyances

experience

programming
paradigms

goal

compiler small

library large (and extensible)

how?

- built-in types
- built-in controls

+ native interface
+ sufﬁciently low-level primitives
+ abstraction mechanisms (screens,
controls, functions, types)

native interface
external type Object {
sync function toString() : String
}

external type String : Object {
length : Num
sync function charAt(index : Num) : String
sync function charCodeAt(index : Num) : Num
...
}

external type Num : Object { }
external type Bool : Object { }
external type Dynamic : Object { }
external type Style : String { }

external type Array<T> {
length : Num

sync function get(n : Num) : T
sync function push(item : T) : void
sync function join(sep : String) : String
...
}

low-level primitives

control image(url : String, onclick : Callback = null) {
<img src=url onclick=onclick/>
}


control slideupBlock() {
div@<div onclick={
div.slideUp();
}>
elements()
</div>
}

...

slideupBlock {
label("Click me to slide up")
}


control slideupBlock() {
JQuery div@<div onclick={
div.slideUp();
}>
elements()
</div>
}

...

slideupBlock {
label("Click me to slide up")
}

.limit(10);

where done == true
order by date desc
limit 10;

div.header {
background: -webkit-gradient(linear, 0% 0%, 0% 100%,
from(rgb(72, 100, 180)), to(rgb(32, 60, 140)));
background: -moz-linear-gradient(top, rgb(72, 100, 180),
rgb(32, 60, 140));
padding: 0;
height: 2.3em;
font-size: 1.3em;
line-height: 2.3em;
font-weight: bold;
text-align: center;
text-shadow: #477 0px 1px 1px;
color: white;
font-weight: bold;
margin: 0;
z-index: 2;
}

issue

out of sight,
no checking
out of mind

<div class="headerr">
</div>

little abstraction

div.header {
from(rgb(72, 100, 180)), to(rgb(32, 60, 140)));
rgb(32, 60, 140));
padding: 0;
height: 2.3em;
font-size: 1.3em;
line-height: 2.3em;
font-weight: bold;
text-align: center;
color: white;
font-weight: bold;
margin: 0;
z-index: 2;
}

little abstraction

div.header { mixins
from(rgb(72, 100, 180)), to(rgb(32, 60, 140)));
rgb(32, 60, 140));
padding: 0;
height: 2.3em;
font-size: 1.3em;
line-height: 2.3em;
font-weight: bold;
text-align: center;
color: white;
font-weight: bold;
margin: 0;
z-index: 2;
}




3b. support common native interface cases
with core abstractions

mobl - model-driven engineering lecture

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