the ouroboros methodology - bguse112/wiki.files/ourb-method.pdf · guy wiener (bgu) the ouroboros...

The Ouroboros Methodology

Guy Wiener

Ben-Gurion University

13/6/2011

Software Engineering 2011

Guy Wiener (BGU) The Ouroboros Methodology 13/6/2011 1 / 58

Software Development Methodologies Today

Agile

Develop

TestRefactor

Model-Based

Itemname

Displayscreen

System

parts


Model-Driven Development


Using Software Models

Testing before buildingGuidingValidatingCommunicatingVisualizingReducing complexityRaising the level of abstractionStoring knowledgeGenerating code


Model-Driven Development

ProsStores knowledgePowerful tools

ConsAdds ceremonySlows down changes


Agile Development


Agile Development

The Agile ManifestoIndividuals and interactions over processes and toolsWorking software over comprehensive documentationCustomer collaboration over contract negotiationResponding to change over following a plan


Agile Development


Agile Development

Agile practicesTime-framed iterations, often shortLow amount of ceremonyCustomer feedbackTestingRefactoring


Agile Development

ProsResponsive to changeLess administrativa

ConsLooses knowledgeNo tools support


Bridging the Gap

Lightweight modelingLink specs and codeModel queriesRound-trip workflow


The Ouroboros Workflow

Model

Query Link

Code


Outline

1 Background

2 Modeling

3 Queries and Views

4 Coding and Linking

5 Summary


Background

Outline

1 BackgroundOPMProlog

2 Modeling

3 Queries and Views


5 Summary


Background OPM

Outline


2 Modeling

3 Queries and Views


5 Summary


Background OPM

OPMObject-Process Methodology (Dori 2002)

FeaturesSimple: ∼ 20 basic declarationsSingle diagram typeDual representation: Textual and graphicalScaling operators

Language Elements

EntitiesObjectsProcessesStates

RelationsBuilt-inTagged


Background OPM

OPD

Object-Process DiagramsObjects are boxesProcesses are ellipses

Object states are octagonsRelations are arrows

Entities and Relations

X Yf

Tagged relation f

X Y X instance Y

X Y Y extends X

X Y X consists Y

X Y X exhibits Y

X Y X implements Y

X Y X invokes Y

X Y X yields Y

X Y Y requires X

X Y X handles Y


Background OPM

OPDExample Diagram

person

married

single

couple

man

woman

rabbi

marrying

registry

ring

1..2


Background OPM

OPL

Object-Process LanguageA textual format for OPMComposed of sentencesEach sentence is a declaration or a relation


Background OPM

OPLExample paragraph

object person states single, married.object man, woman, couple, registry, rabbi, ring.process marrying.man, woman extends person.couple consists man, woman.marrying changes person from single to married.marrying consumes ring(1,2).marrying yields couple.


Background Prolog

Outline


2 Modeling

3 Queries and Views


5 Summary


Background Prolog

Prolog

Origin1972 — Alain Colmerauer designs the logic language Prolog. Hisgoal is to create a language with the intelligence of a two year old.He proves he has reached his goal by showing a Prolog session thatsays "No." to every query.

(Taken from the brief, incomplete, and mostly wrong history ofprogramming languages by James Iry)


Background Prolog

Prolog in a Nutshell

father(john, jack).mother(jane, jack).father(john, jill).mother(jane, jill).father(jim, jules).mother(jill, jules).

parent(X, Y) :- father(X, Y).parent(X, Y) :- mother(X, Y).

sibling(X, Y) :-parent(Z, X),parent(Z, Y),X \= Y.

only_child(X) :-\+ sibling(X, _).

?- father(john, X), mother(Y, X).X = jack, Y = jane ;X = jill, Y = jane


Background Prolog







Atom

Functor

Variable


Background Prolog







Fact

Rule

HeadBody


Background Prolog







Query

Assignment

Goal

Negation


Modeling

Outline

1 Background

2 Modeling

3 Queries and Views


5 Summary


Modeling

Ouroboros Models

An example model

object person states single, married.object man, woman, couple, registry, rabbi, ring.process marrying.man, woman extends person.couple consists man, woman.marrying changes person from single to married.marrying consumes ring(1,2).marrying yields couple.


Modeling

Ouroboros Models

Prolog predicates for the example model

object(person).object(man).object(woman)....process(marrying).state(person::single).state(person::married).

extends(man, person).extends(woman, person).consists(couple, man).consists(couple, woman).consumes(marrying, ring).produces(marrying, couple)....


Modeling

Model Programming

Model rules

process(listener(W)) :- instance(W, window).requires(listener(W), W) :- instance(W, window).


Queries and Views

Outline

1 Background

2 Modeling

3 Queries and ViewsQueriesViews


5 Summary


Queries and Views Queries

Outline

1 Background

2 Modeling



5 Summary



Queries

Objects in the system

?- object(X).X = person ;X = man ;X = woman; ...

What extends a base?

?- extends(X, person).X = man ;X = woman

Relations in the system

?- relation(R).R = consists ;R = extends ; ...

How two things arerelated?

?- relation(R),call(R, couple, man).

R = consists.



More Queries

Use cases

use_case(Proc) :-process(Proc),object(User),handles(User, Proc),\+ (process(Top), consists(Top, Proc)).



More Queries

Conversion functions

convert(Proc, From, To) :-process(Proc),consumes(Proc, From),yields(Proc, To),\+ requires(Proc, _),\+ handles(_, Proc),\+ (consumes(Proc, X), X \= From),\+ (yields(Proc, Y), Y \= To).


Queries and Views Views

Outline

1 Background

2 Modeling



5 Summary



Views

How to partition a complex system?1 Define a view predicate2 Run graphical or textual visualizations

Example view – A system diagram

sd(object(X)) :- use_case(U), handles(X, U).sd(process(U)) :- use_case(U).sd(handles(X, U)) :- handles(X, U).



Views

Example view – A system diagram

?- sd(X).X = process(marrying) ;X = object(rabbi) ;X = handles(rabbi, marrying)

Textual

process marrying.object rabbi.rabbi handles marrying.

Graphical

rabbi marrying


Coding and Linking

Outline

1 Background

2 Modeling

3 Queries and Views

4 Coding and LinkingCode SummaryLinking Code and SpecsIntegrated Queries

5 Summary


Coding and Linking Code Summary

Outline

1 Background

2 Modeling

3 Queries and Views


5 Summary



From Source Code To Facts

What is needed?Syntactic parsingRepresent parsed code in knowledge base

Existing logic parsersErlang The parsed code is part of the debug infoJava JTransformer (over Eclipse), JTL



Importing Parsed Code

An Erlang Program — Records

-module(login_srv).-record(user,{username, password, name}).-record(login_ok,{username, time}).-record(login_fail,{username, password, time}).




An Erlang Program — Functions

start() ->% Server init code...

login(Username, Password) ->Users = get(users),Log = get(log), ...

last_attempt(Username) ->Log = get(log), ...

failed_attempts(Username) ->Log = get(log), ...




Parsed Code — Records

erl_file(’login_srv.erl’,[attribute(1, file, ’login_srv.erl’(1)),attribute(1, module, login_srv),attribute(2, export, [...]),attribute(4, record,user([record_field(4, atom(4, username)),

record_field(4, atom(4, password)),record_field(4, atom(4, name))])),

...




Parsed Code — Functions

function(12, login, 2,[clause(12,

[var(13, ’Username’), var(13, ’Password’)], [],[match(15, var(14, ’Users’),

call(14, atom(14, get),[atom(14, users)])),

match(15, var(15, ’Log’),call(15, atom(15, get),

[atom(15, log)])),...]

)])...]).



Code Summary

Code

create_disk_log(Filename,MaxBytes, MaxFiles,ConfigList) ->Format = proplists:get_value(disk_log_fmt,ConfigList, external),open(Filename, MaxBytes,MaxFiles, Format).

Summary

create_disk_log

get_value open

proplists



Code Summary

Rules

object(erl:Record) :- erl_record(Record).object(erl:Field) :- erl_record_field(_, Field).exhibits(erl:Record, erl:Field) :-erl_record_field(Record, Field).

object(erl:Module) :- erl_module(Module).process(erl:Name) :-erl_func(_, _, _, Name).

exhibits(erl:Module, erl:Name) :-erl_func(Module, _, _, Name).



Code Summary

erl:log

erl:login_srv

erl:users

erl:login_srv:failed_attempts

erl:login_srv:last_attempt

erl:login_srv:loginerl:login_srv:start

erl:login_fail

erl:password erl:timeerl:username

erl:login_ok

erl:name

erl:user


Coding and Linking Linking Code and Specs

Outline

1 Background

2 Modeling

3 Queries and Views


5 Summary



Synchronizing the Model and Code

The implements relationimplements(Imp, Spec) The entity Imp implements Spec.

Detecting where the model and the code arenot synchronized\+implements(_, Thing) Thing has no implementation.\+implements(Thing, _) Thing has no specification.



Linking Specs and Code SummaryThe specifications

log_entry

login_fail

login_ok

time

username password

login_srv

log

0..n

userusers

0..n

failed_attempts

last_attempt

login

start

name



Linking Specs and Code SummarySpecification and Implementation

The implements relation

erl:login_ok implements login_ok.erl:time implements time.

implements(erl:X, Y) :- ...

Specs and SummarySummary reflects codestructureSpecs use modelingabstractions

log_entrytimeusername

login_fail

password

login_ok

erl:login_fail

erl:password

erl:timeerl:username

erl:login_ok


Coding and Linking Integrated Queries

Outline

1 Background

2 Modeling

3 Queries and Views


5 Summary



Compatibility

Persistency check

no_persistency :-object(X),\+ (process(P),

consist(P, X)),\+ implements(sql:_, X).

Compatibility queriesValidate policyFind irregulars



Impact Analysis

Connected

connected(X, Y, R) :-relation(R),call(R, X, Y).

Also has a recursive version

Context queriesTraceabilityImpactProximity



Incremental Changes

Missing implementation Update code and re-linkMissing specification Update specs and re-linkFailed policy check Fix matched codePlanned changes Consult impact analysis


Summary

Outline

1 Background

2 Modeling

3 Queries and Views


5 Summary


Summary

Software Modeling in an Agile Environment

Modeling with minimaladded ceremonyQueries provide immediatebenefitPreserves domainknowledgeIdentifies and supportsincremental changes


Summary

Not Discussed Here

Model programming (in depth)Code generation

Compatibility rules + Existing code factbase =Generate missing code

Model extractionPatterns, platforms and their properties


Summary

Links and References

OPM “Object-Process Methodology: A Holistic SystemPardigm”, Dov Dori, 2002

Erlang http://www.erlang.org/

JTransformer http://sewiki.iai.uni-bonn.de/research/jtransformer/

Ouroboros http://www.cs.bgu.ac.il/~gwiener/software/opmpl/


http://www.erlang.org/

http://sewiki.iai.uni-bonn.de/research/jtransformer/

http://sewiki.iai.uni-bonn.de/research/jtransformer/

http://www.cs.bgu.ac.il/~gwiener/software/opmpl/

http://www.cs.bgu.ac.il/~gwiener/software/opmpl/

Summary

Thank you!

Questions?


the ouroboros methodology - bguse112/wiki.files/ourb-method.pdf · guy wiener (bgu) the ouroboros...

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