View source for OCL/Articles

= Articles and Presentations =

== 2021 ==

* [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/OCL2021Validity/OCLValidity.pdf "A Validity Analysis to Reify 2-valued Boolean Constraints"], E.D.Willink, [https://oclworkshop.github.io/2021 "20th International Workshop in OCL and Textual Modeling (OCL 2021)"], June 2021, [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/OCL2021Validity/OCLValidity.odp "slides"]

Making OCL crash-proof.

== 2020 ==

* Reflections on OCL 2, E.D.Willink, [https://www.omg.org/events/2020Q2/agendas/AnalysisDesignPTFCalendar.html "ADTF @ OMG VIRTUAL Technical Committee Meeting – JUNE 22-26, 2020"], June 2020, [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/OMG2020Jun/OMG2020Reflections.odp "slides"]

Review of the sad OCL state of the art emphasizing the OMG-related aspects of the problems.

* [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/JOT2020OCLReflections/OCLReflections.pdf "Reflections on OCL 2"], E.D.Willink, [https://www.omg.org/events/2020Q2/agendas/AnalysisDesignPTFCalendar.html "ADTF @ OMG VIRTUAL Technical Committee Meeting – JUNE 22-26, 2020"], June 2020

Review of the sad OCL state of the art emphasizing the OMG-related aspects of the problems.

== 2019 ==

* OCL 2019 Keynote Retrospective and Prospective, E.D.Willink, [https://oclworkshop.github.io/2019 "19th International Workshop in OCL and Textual Modeling (OCL 2019)"], September 2019, [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/OCL2019Keynote/OCL2019Keynote.odp "slides"]

Review of the OCL history and future prospects.

* [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/OCL2019Visuals/OCLVisualization.pdf "OCL Visualization - A Reality Check"], E.D.Willink, [https://oclworkshop.github.io/2019 "19th International Workshop in OCL and Textual Modeling (OCL 2019)"], September 2019, [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/OCL2019Visuals/OCLVisualization.odp "slides"]

Review of 5 alternative visualizations of OCL.

* [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/OCL2019MapType/OCLMapType.pdf "An OCL Map Type"], E.D.Willink, [https://oclworkshop.github.io/2019 "19th International Workshop in OCL and Textual Modeling (OCL 2019)"], September 2019, [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/OCL2019MapType/OCLMapType.odp "slides"]

Description of the Eclipse Pivot OCL Map Type.

== 2017-2018 / Photon, 2018-09, 2018-12 ==

* Shadow Objects, E.D.Willink, [http://http://oclworkshop.github.io/2017 "18th International Workshop in OCL and Textual Modeling (OCL 2018)"], October 2018, [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/OCL2018Shadows/Shadows.odp "slides"]

A lightning presentation on the limitations of support for type construction within OCL.

* [http://www.eclipse.org/mmt/qvt/docs/OCL2018TextM2M/TextM2M.pdf "A text model - Use your favourite M2M for M2T."], E.D.Willink, [https://oclworkshop.github.io/2018 "18th International Workshop in OCL and Textual Modeling (OCL 2018)"], October 2018, [http://www.eclipse.org/mmt/qvt/docs/OCL2018TextM2M/TextM2M.odp "slides"]

A simple solution to using any M2M for M2T; use a standard text metamodel and exploit EMF Resource flexibility to save the text model as plain text. Also provides a solution to XML2XMLwith any M2M tool. Suggests some M2T-friendly OCL extensions.

Models provide a disciplined representation of information. Model-to-Model (M2M) transformations convert between model structures. When a more readable representation is required, Model-to-Text (M2T) transformations convert a model structure to a concatenation of character sequences. We ignore the obvious conversion differences and demonstrate that an unmodified M2M tool can be used for M2T. We achieve this with a standard Text model that post-processes the M2M model output to yield formatted text. 

* [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/OCL2017Evaluation/LazyDeterminism.pdf "Deterministic Lazy Mutable OCL Collections"], E.D.Willink, [http://http://oclworkshop.github.io/2017/news.html "17th International Workshop on OCL and Textual Modeling (OCL 2017)"], July 2017, [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/OCL2017Evaluation/LazyDeterminism.odp "slides"]

The Collection iterations and operations are perhaps the most important part of OCL.

It is therefore important for an OCL evaluation tool to provide efficient support for Collections. Unfortunately, some clauses of the OCL specification appear to inhibit efficient or deterministic support. We review the inhibitions and demonstrate a new deterministic and lazy implementation that avoids them.

* [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/OCL2017ShortCircuits/ShortCircuits.pdf "Commutative Short Circuit Operators"], E.D.Willink, [http://oclworkshop.github.io/2017/news.html "17th International Workshop on OCL and Textual Modeling (OCL 2017)"], July 2017,  [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/OCL2017ShortCircuits/ShortCircuits.odp "slides"]

Lightning talk : OCL's 4-valued logic is a source of much unhappiness. We attempt to recreate the design decisions that led to the current design and thereby suggest solutions to escape from it.

== 2016-2017 / Oxygen==
* [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/OCL2016Opposites/Opposites.pdf "The Importance of Opposites"], E.D.Willink, [http://oclworkshop.github.io/2016/news.html "16th International Workshop on OCL and Textual Modeling (OCL 2016)"], October 2016, [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/OCL2016Opposites/Opposites.odp "slides"]

Lightning presentation explaining the importance of unnavigable opposites; particularly for the QVTc trace.

* [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/OCL2016Spec/OCLStatus.odp "OCL Specification Status"], E.D.Willink, [http://oclworkshop.github.io/2016/news.html "16th International Workshop on OCL and Textual Modeling (OCL 2016)"], October 2016

'Keynote' presentation on the slow progress towards OCL '2.5'.

== 2015-2016 / Neon ==
* [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/ICMT2016CS2AS_DSTL/icmt2016.pdf "A DSTL to Bridge Concrete and Abstract Syntax"], Adolfo Sánchez-Barbudo Herrera, Edward D. Willink, Richard F. Paige, [http://is.ieis.tue.nl/research/ICMT16/ "9th International Conference on Model Transformation(ICMT 2016)"], July 2016. [http://es.slideshare.net/adolfosbh/a-dstl-to-bridge-concrete-and-abstract-syntax slides]

* [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/OMG2015Dec/OCLRoadmap.odp "OCL Roadmap"], E.D.Willink, OMG quarterly meeting, December 2015

Consideration of alternative OCL 'next' specification approaches.

* [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/EclipseConEurope2015/OCLDebuggerAtLast.odp "At last an OCL Debugger"], E.D.Willink, [https://www.eclipsecon.org/europe2015/ "EclipseCon Europe 2015"], November 2015

Eclipse OCL debugger promo.

* [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/EclipseConEurope2015/OCLforUMLProfile.odp "The OCLforUML Profile"], E.D.Willink, [https://www.eclipsecon.org/europe2015/ "EclipseCon Europe 2015"], November 2015

Introduction to the OCLforUML profile, validation, collections, numeric stereotypes.

* [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/OCL2015SafeNavigation/SafeNavigation.pdf "Safe Navigation in OCL"], E.D.Willink, [https://ocl2015.lri.fr/ "15th International Workshop on OCL and Textual Modeling Applications and Case Studies (OCL 2015)"], September 2015

Problems and solutions for the introduction of ?. and ?-> operators to (Eclipse) OCL. [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/OCL2015SafeNavigation/SafeNavigation.odp "slides"]

* [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/OCL2015CS2AS/ow2015.pdf "An OCL-based Bridge from Concrete to Abstract Syntax"], Adolfo Sánchez-Barbudo Herrera, Edward Willink, Richard F. Paige, [https://ocl2015.lri.fr/ "15th International Workshop on OCL and Textual Modeling Applications and Case Studies (OCL 2015)"], September 2015. [http://es.slideshare.net/adolfosbh/an-oclbased-bridge-from-cs-to-as slides]

The forthcoming automation for the CS to AS conversion.

== 2014-2015 / Mars ==

* [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/OCL2014OCLDebug/OCL2014OCLDebug.pdf "Embedded OCL Integration and Debugging"], E.D.Willink, [http://www.software.imdea.org/OCL2014/ "14th International Workshop on OCL and Textual Modeling Applications and Case Studies (OCL 2014)"], September 2014

Techniques used by Eclipse OCL to enable OCL to be used and debugged with a larger application. [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/OCL2014OCLDebug/OCL2014Debug.odp "slides"]

* [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/OCL25Plans/OCL25Plans.odp "OCL 2.5 Plans"], E.D.Willink, [http://www.software.imdea.org/OCL2014/ "14th International Workshop on OCL and Textual Modeling Applications and Case Studies (OCL 2014)"], September 2014

State of the art report on plans for OCL 2.5.

== 2013-2014 / Luna ==

* [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/EclipseConEurope2013/OCLIntegrationAndCodeGeneration.odp "OCL Integration and Code Generation"], E.D.Willink, [https://www.eclipsecon.org/europe2013/ "EclipseCon Europe 2013"], October 2013

Lightning presentation on the Java code generator for Eclipse OCL.

* [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/OMG2013Sep/ADTFOCL2013.odp "OCL 2.4 (... OCL 2.5)"], E.D.Willink, [http://ocl2013.inf.mit.bme.hu/ "13th International Workshop on OCL, Model Constraint and Query Languages (OCL 2013) "], September 2013

Presentation on changes in OCL 2.4 and future plans. Also presented in part to OMG ADTF.

== 2012-2013 / Juno ==

* [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/EclipseConNA2012/EclipseCon2012.pdf "Eclipse OCL for Juno"], E.D.Willink, [http://www.eclipsecon.org/2012/sessions/modeling-symposium "EclipseCon Modeling Symposium"], March 2012

Very brief presentation/demonstration of the new facilities in Juno; Code Generation and Complete OCL loading.

* [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/EclipseOMG2012/EclipseOMG2012.pdf "OCL Advances and the OCL VM"], E.D.Willink, [http://www.omg.org/news/meetings/tc/dc-12/special-events/Eclipse_Program.htm "Joint Eclipse/OMG Workshop"], March 2012

Brief comparison of OCL/Xbase roles. Overview of OCLinEcore and Complete OCL editors. Description of the primary features of the OCL VM; polymorphic values, fast operation dispatch and extensibility to QVT.

* [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/OMG2012Mar/ADTFOCL2012.pdf "OCL omissions and contradictions"], E.D.Willink, [http://www.omg.org/news/meetings/tc/dc-12/info.htm "OMG Quarterly Meeting"], March 2012

Presentation to the OMG Architecture and Design Domain Task Force on the current direction of work on OCL with particular emphasis on potentially controversial topics.

* [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/OCL2012OCLVM/OCL2012OCLVM.pdf "An extensible OCL Virtual Machine and Code Generator"], E.D.Willink, [http://st.inf.tu-dresden.de/OCL2012/ "2012 Workshop on OCL and Textual Modelling (OCL 2012)"], September 2012

Brief overview of the code generator technology. [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/OCL2012OCLVM/OCL2012OCLVM.odp "slides"]

* [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/EclipseConEurope2012/FastQueries.pdf "Fast, Faster and Super-Fast Queries"], István Ráth, Edward Willink, [http://www.eclipsecon.org/europe2012/ "EclipseCon Europe 2012"], October 2012

Joint OCL, EMF-IncQuery presentation on OCL Code Generator (fast), OCL VM (faster) and incremental query matching (super-fast).

== 2011-2012 / Indigo ==

* [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/OMG2011Dec/OMG2011Dec.pdf "OCL Tooling for OMG specifications"], OMG Quarterly Meeting, December 2011

Presentation to the UML Simplification Working Group on the current direction of work on OCL and on initial results from using Eclipse OCL tooling for the UML 2.5 constraints.

* [http://www.slideshare.net/EdWillink/enrich-your-models-with-ocl "Enrich Your Models With OCL"], Edward Willink and Axel Uhl, EclipseCon Tutorial, 2011

The utility of the Object Constraint Language for modeling within Eclipse has increased dramatically in the last few years, so that Eclipse OCL is now useful for everyday modelers rather than just advanced Java programmers.

This tutorial will demonstrate to existing EMF users how OCL in isolation can enhance their models and how the Eclipse support is re-used within advanced model transformation tools.

The tutorial will first introduce OMG's OCL language and its capabilities, then show how OCL can be embedded within Ecore to support validation and evaluation of dynamic EMF models without using genmodel at all. This part of the tutorial will introduce the OCLinEcore text editor that supports the combined development of OCL and Ecore, the CompleteOCL editor that supports complementary development of OCL and the the Interactive OCL Console that supports interactive evaluation.

Models developed during the Ecore integration part of the tutorial will be elaborated during the rest of the tutorial to demonstrate how model representations can be transformed using model to model transformations and then presented in human-friendly fashion by model to text transformations.

The model to model transformation section of the tutorial will provide a brief overview of OMG's QVT Operational Mappings language and Eclipse's M2M/QVTo tooling, while developing the running example with particular emphasis on the use of OCL to perform complex navigations and queries.

The model to text transformation section of the tutorial will provide similar brief overviews of OMG's M2T language and Eclipse's M2T/Acceleo tooling. The running example will be elaborated to showing more extensive use of OCL.

OCL supports the formulation of very compact queries that it is useful to practice. The tutorial will demonstrate this style of working by providing regular opportunities to configure and use some OCL facility with additional challenges for those participants who find the basic examples too easy. 

* [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/TUIlmenau2011ImpactAnalysis/OCL%20Impact%20Analysis.pdf "Efficient OCL Impact Analysis"], Thomas Goldschmidt and Axel Uhl, presented at Heidelberg University, 2011

* [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/OCL2011AligningOCLandUML/AligningOCLandUML.pdf "Aligning OCL with UML"], Edward Willink, [http://gres.uoc.edu/OCL2011/ "OCL 2011, Workshop on OCL and Textual Modelling"], TOOLS 2011

OCL is widely used by UML and other languages to constrain metamodels
and perform evaluations on models. Unfortunately no OCL 2.x specification
has ever been aligned with any UML 2.x specification. This lack of alignment makes
some OCL compliance points such as XMI interchange unachievable. This paper
describes how introduction of an OCL Pivot Meta-Model and clear exposition of
the Values package may provide a solution to the alignment and a variety of other
specification issues.

* [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/OCL2011ModelingOCLstdlib/ModelingOCLstdlib.pdf "Modeling the OCL Standard Library"], Edward Willink, [http://gres.uoc.edu/OCL2011/ "OCL 2011, Workshop on OCL and Textual Modelling"], TOOLS 2011

OCL is widely used by UML and other languages to constrain metamodels
and perform evaluations on models. The OCL specification is the result of
diligent but time-constrained human endeavor and so contains many inconsistencies,
most of which are relatively easy to ignore as obvious typographical mistakes.
However the need to ignore minor discrepancies undermines rigorous treatment of
more significant issues. The minor issues can be substantially eliminated by autogenerating
the specification. This paper provides early community visibility of proposed
solutions to a variety of issues that arose while developing a model for the
OCL Standard Library that forms the core of the OCL specification.

== 2010-2011 / Helios==

* [http://www.slideshare.net/EdWillink/enriching-withocl "Enrich Your Models With OCL"], Adolfo Sanchez-Barbudo Herrera, Axel Uhl and Edward Willink, Eclipse Summit Europe Long Talk, 2010

The utility of the Object Constraint Language for modeling within Eclipse has increased dramatically in the last few years, so that MDT/OCL is now useful for everyday modelers rather than just advanced Java programmers. This long talk is focused on both non-OCL users and advanced OCL users so that any kind of audience may learn how OCL can enhance your (meta-)model definitions and how OCL forms the foundation of advanced modeling technologies such as Acceleo and QVT.

In the first part of the talk, focused on modelers who have yet to discover OCL, you will get a short introduction to the OMG's OCL language and its main capabilities. Then you will learn how OCL can be embedded within Ecore to define constraints for validation, operation bodies for evaluation and derived features for initialization of EMF models (both dynamic instances and those from generated Java classes using "genmodel"). A presentation of the OCL Interactive Console will be used to help the user to alternatively write and validate their OCL constraints.

Finally, focusing on the advanced OCL audience, you will learn about ongoing work to exploit Xtext to provide an enhanced OCL development environment and of OCL to define its own editors and language semantics. Extensive use of OCL within OCL mandates a dramatic performance improvement requiring a flexible Java code generator for an efficient first evaluation of an OCL expression and an impact analysis to avoid redundant re-evaluation following a model change.

* [http://www.eclipse.org/modeling/mdt/ocl/docs/publications/MODELS2010OCLWorkshop/oclxtext.pdf "Re-engineering Eclipse MDT/OCL for Xtext"], Edward Willink, [http://modeling-languages.com/events/OCLWorkshop2010/ "OCL 2010, Workshop on OCL and Textual Modelling"], MODELS 2010

The current tooling used for the Eclipse OCL project uses an LALR parser generator. Enhancing the tooling to support editing motivated a migration to exploit the inherently model-driven characteristics of Xtext. This paper summarizes the experiences of that migration, identifies the many benefits and discusses a few changes in implementation approach that were required. Objective performance and size comparisons between the old LALR and new Xtext approach are provided.

== 2008 ==

* [http://joanna.opoki.com/papers/2008_MoDeVVa/paper.pdf "Querying UML Models using OCL and Prolog: A Performance Study"] presented at [http://www.cs.colostate.edu/~ghosh/modevva2008/ MoDeVVa'2008] by Joanna Chimiak-Opoka et al. <br>(OCL expressions used in the study are available online at the [http://squam.info/ocleditor/ OCL Editor web page] in the Library Concept / Concrete Syntax section)

The size of Unified Modeling Language (UML) models
used in practice is very large and ranges up to hundreds
and thousands of classes. Querying of these models is used
to support their quality assessment by information filtering
and aggregating. For both, human cognition and automated
analysis, there is a need for fast querying. In this context
performance of model queries becomes an important issue.
We investigated performance characteristics of two different
querying engines: one using the Object Constraint Language
(OCL) and the other using Prolog. Our comparison
is based on equivalent queries in both languages. We applied
the queries to 118 models of a size up to 10000 classes
to analyze model load and evaluation time. Our preliminary
results show that if execution time of queries is linear then
Prolog is faster. For one of the presented cases, the execution
time in Prolog was nonlinear and thus higher. Further
studies should focus on a performance analysis reflecting
expressiveness aspects. Our experimental material is accessible
to enable future replications of this study.

== 2007 ==

* [http://www.sts.tu-harburg.de/~mi.garcia/pubs/2007/ocltools/OCLTools.pdf OCL Tools: Status and Perspectives] by Miguel Garcia and A. Jibran Shidqie

With the availability of infrastructural support for OCL (Object Constraint Language)
provided by MDT OCL, the next step consists in simplifying the authoring of OCL
speci�cations with feature-rich tools, as part of the more general task of model author-
ing. The capabilities of the OCL Tools project are described (currently they comprise
an OCL ! Java compiler and a text editor for OCL). A discussion of areas for im-
provement and related work follows (refactoring of OCL expressions, detecting code
smells, analyzing and optimizing OCL expressions). These ideas for future work fall
under the umbrella of model compilers, essential elements of Model-Driven Software
Engineering.

* [http://www.sts.tu-harburg.de/~mi.garcia/pubs/2007/ese/oclcompiler.pdf OCL Compiler for EMF] by Miguel Garcia and A. Jibran Shidqie

The Eclipse infrastructure for modeling is based on EMF, with support for OCL 2.0 provided by the Model
Development Tools (MDT) project. The combined expressive power of Ecore + OCL allows capturing a sizable
amount of development requirements in a declarative manner: (a) data modeling aspects can be expressed as an
Ecore-based schema further constrained by OCL invariants; (b) a number of functional requirements can be specified
as operation pre- and postconditions, together with side-effects-free queries. The OCL compiler reported in this
paper extends the code generation process of EMF by performing a translation from OCL types and expressions into
Java types and statements, increasing productivity and quality measures of a Model-Driven Software Development
(MDSD) process. The generated code can be directly used as the Model component in an MVC architecture (for
example, as part of a graphical editor generated with Eclipse GMF).

* [http://www.eclipse.org/articles/article.php?file=Article-HowToProcessOCLAbstractSyntaxTrees/index.html How to process OCL Abstract Syntax Trees] by Miguel Garcia

The Model Development Tools Object Constraint Language (MDT OCL) project provides the building blocks for Model-Driven tools to weave OCL declarative specifications into software artifacts. We showcase some of these possibilities, taking as starting point a plug-in to visualize OCL abstract syntax trees (ASTs) in the form of annotated trees. This example motivates some practical tips about patterns for OCL visitors, including using Java 5 generics and achieving conciseness by letting MDT OCL take care of the "walking" order. To really reap the benefits of OCL-enriched specifications, tools in our modeling chain have to be able to transform such expressions into the target software platform (e.g. compile into Java, translate into SQL). Work in this area is summarized, to ease jump-starting your own OCL processing project.

* [http://www.eclipse.org/articles/Article-EMF-Codegen-with-OCL/article.html Implementing Model Integrity in EMF with OCL] by Christian W. Damus

This article illustrates how the MDT OCL parser/interpreter technology adds to the value of EMF/JET code generation as a foundation for model-driven development (MDD). We will see, with fully functional examples, how a model can be generated from an Ecore specification without requiring any post-generation custom code, including complete implementations of:
** invariant constraints
** derived attributes and references
** operations

* [http://www.slideshare.net/dmsteinberg/eclipsecon-2007-effective-use-of-the-eclipse-modeling-framework EclipseCon 2007 tutorial "Effective Use of the Eclipse Modeling Framework"] by Ed Merks et al.