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

Develop

TestRefactor

Model-Based

Itemname

Displayscreen

System

Model-Driven Development

Using Software Models

Testing before buildingGuidingValidatingCommunicatingVisualizingReducing complexityRaising the level of abstractionStoring knowledgeGenerating code

ProsStores knowledgePowerful tools

ConsAdds ceremonySlows down changes

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 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

Query Link

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

Object-Process DiagramsObjects are boxesProcesses are ellipses

Object states are octagonsRelations are arrows

Entities and Relations

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

marrying

registry

Background OPM

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

Functor

Variable

Background Prolog

HeadBody

Background Prolog

Assignment

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

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).

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

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

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

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.

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

username password

login_srv

userusers

failed_attempts

last_attempt

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/

Summary

Thank you!

Questions?

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

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