presented by Lukas Renggli at the CHOOSE Forum 2012

1. Practical Models
in Practice
www.lukas-renggli.ch

2. Practical Models of
Models in Practice
www.lukas-renggli.ch

3. Practical Meta-
Models in Practice
www.lukas-renggli.ch

4. Lukas Renggli
‣ Software Engineer at Google
YouTube Video Analytics
‣ SCG Alumni
Bachelor, Master and PhD
‣ Open-Source Communities
Seaside, Magritte and Pier
Helvetia, PetitParser

5. Roadmap
1. Protocol Buffers
Meta-data model for serialization
2. Magritte
Meta-model for generic services
3. Google Web Toolkit
Model-driven web architecture
4. Helvetia
Meta-model for programming languages

6. Protocol Buffers
Meta-data model for serialization

7. Protocol Buffers
‣ Encode structured data
‣ Language-neutral
‣ Platform-neutral
‣ Extensible
‣ Efficient

8. Protocol Buffer IDL
message Person {
required int32 id = 1;
required string name = 2;
optional string email = 3;
}

9. message Person {
required int32 id = 1;
required string name = 2;
optional string email = 3;
}
protoc
C++

10. Serialize in C++
Person person;
person.set_name("John Doe");
person.set_id(1234);
person.set_email("jdoe@example.com");
fstream output("myfile", ios::out | ios::binary);
person.SerializeToOstream(&output);

11. Deserialize in Python
file = open("myfile", "rb")
person = Person()
person.ParseFromString(file.read())
file.close
print "Name: ", person.name
print "E-mail: ", person.email

12. Demo

13. Why not XML/JSON?
‣ Protocol Buffers are
– 3—10 times smaller
– 20—100 times faster
– consistent code generators
– less ambiguous
– evolvable

14. message Person { message Person {
required int32 id = 1; required int32 id = 1;
required string name = 2; required string name = 2;
optional string email = 3; repeated string email = 3;
} repeated Phone phone = 4;
}
:Person
:Person
:Person

15. ‣ Describe your data once, and use it
across platforms and languages
‣ Evolution supported by design
‣ Used at Google for almost all
– data storage (file formats, database)
– remote procedure protocols (RPC)

16. Magritte
Meta-model for generic services

17. Address Object
:Address
street = 'Schützenmattstrasse'
plz = 3012
place = 'Bern'
canton = 'Bern'

18. Address Class
:Address Address
street = 'Schützenmattstrasse' class street: String
plz = 3012 plz: Integer
place = 'Bern' place: String
canton = 'Bern' canton: String

19. Address Description
Magritte :StringDescription
label = 'Street'
:NumberDescription
label = 'PLZ'
required = true
:Address range = 1000..9999
street = 'Schützenmattstrasse' description :StringDescription
:Container
plz = 3012 label = 'Place'
label = 'Address'
place = 'Bern' required = true
canton = 'Bern'
:SingleOptionDescription
label = 'Canton'
required = true
sorted = true
options = #( 'Bern' 'Zurich' ... )

20. User Interfaces
result := anAddress asMorph
addButtons;
addWindow;
callInWorld

21. Web Interfaces
result := self call: (anAddress asComponent
addValidatedForm;
yourself)
*
*
*

22. Other Services
Reports
Viewers Filtering
Editors Validation
Serialization Initialization
Indexing
Copying Initialization
Extension Customization
Adaptation

23. Meta-
Metamodel
<described-by>
Metamodel
Developer
<described-by>
Domain Model
End User

24. Meta-
Metamodel
<described-by>
Metamodel
Magritte
Developer
<described-by>
Domain Model
Magritte
End User

25. Run- t im e
Adaptive
Object Model

26. End users
customizability

27. Demo

28. Magritte
‣ Very powerful and flexible
‣ Runtime adaptive code
‣ End-user programmable code
‣ Can cause meta meta-confusion
‣ Can be slower than hardcoding

29. Google Web Toolkit
Model-driven web architecture

30. Is this really a model?
public class Main implements EntryPoint {
public void onModuleLoad() {
Label label = new Label(“Hello World”);
RootPanel.add(label);
}
}

31. Is this really a model?
public class Main implements EntryPoint {
public void onModuleLoad() {
Label label = new Label(“Hello World”);
RootPanel.add(label);
}
}
High-level
Widgets

32. Is this really a model?
public class Main implements EntryPoint {
public void onModuleLoad() {
Label label = new Label(“Hello World”);
RootPanel.add(label);
}
}
High-level Description
Widgets Language

33. public class Main implements EntryPoint {
public void onModuleLoad() { platform
Label label = new Label(“Hello World”);
RootPanel.add(label); independent
}
} model
model
transformation

34. Transformation
Mozilla Chrome Safari IE ...
English
French
German
...

35. GWT
‣ Write JavaScript using a high-level widget
library in a well defined (statically typed)
language
‣ Translate and optimize code towards
specific browsers
‣ Debugging actually works nowadays

36. He vetia
Helvetia
Meta-model for programming languages

40. Programming
Language
Model

41. ID
::=
letter
{
letter
|
digit
}
;
a..z a..z
0..9

42. scanIdentifier
self step.
((currentCharacter between: $A and: $Z) or:
[ currentCharacter between: $a and: $z ]) ifTrue: [
[ self recordMatch: #IDENTIFIER.
self step.
(currentCharacter between: $0 and: $9)
or: [ (currentCharacter between: $A and: $Z) or:
[ currentCharacter between: $a and: $z ] ] ]
whileTrue.
^ self reportLastMatch ]

43. #( #[1 0 9 0 25 0 13 0 34 0 17 0 40 0 21 0 41]
#[1 0 9 0 25 0 13 0 34 0 93 0 76 0 157 0 112]
#[1 2 38 0 21 2 38 0 25 2 38 0 26 0 13 0 34]
#[0 1 154 0 16 0 21 0 25 0 26 0 34 0 40 0 41]
#[0 1 210 0 76 0 81]
#[0 1 214 0 76 0 81]
#[1 0 173 0 76 0 177 0 81]
#[0 1 134 0 16 0 21 0 25 0 26 0 34 0 40 0 41]
#[1 1 46 0 21 1 46 0 25 1 46 0 26 1 69]
#[1 1 54 0 21 1 54 0 25 1 54 0 26 1 54 0 34]
#[0 2 102 0 21 0 25 0 26 0 34 0 40 0 41 0 76]
#[0 2 50 0 21 0 25 0 26 0 76 0 79]
#[1 1 13 0 76 2 85 0 124 1 21 0 125]
#[1 2 89 0 17 2 30 0 21 2 30 0 82]
#[1 2 93 0 21 2 97 0 82] )

44. ID
::=
letter
{
letter
|
digit
}
;
a..z a..z
0..9
44

45. ID
::=
letter
{
letter
|
digit
}
;
sequence
letter many
choice
letter digit
45

46. Extensible sequence
letter many Composable
choice
Transformable
letter digit
Customizable
46

47. Editors Code
Highlighting
Contextual
He vetia
Menus Custom
sequence Inspector
Navigation
letter many Search
Code choice
Error
Folding
Correction
letter digit
Code
Expansion Debuggers
Refactorings
47

48. Demo

49. He vetia
‣ Grammar is the meta-model
‣ Composable programming languages
‣ Extensible programming languages
‣ Tooling is built around the grammar

50. Structural Behavioral
Model Model
Run-time
Static
Run-time
Adaptive
He vetia

51. “Meta-models are the enablers of
practical software development.”
He vetia
www.lukas-renggli.ch