Preface of the 20th International Workshop on OCL
and Textual Modeling (OCL’2021)
Daniel Calegari1 , Robert Clarisó2 and Edward D. Willink3
1
  Instituto de Computación, Facultad de Ingeniería, Universidad de la República, Uruguay
2
  Universitat Oberta de Catalunya, Rambla del Poblenou 156, 08018 Barcelona, Spain
3
  Willink Transformations Ltd, Reading, England


                                         Abstract
                                         The Object Constraint Language (OCL) is a popular textual modeling language for describing queries
                                         and constraints in object-oriented software development. This paper reports on the 20th International
                                         Workshop on OCL and Textual Modeling (OCL’2021), held in collocation with the STAF federated
                                         conferences. The workshop reflected on improvements to the OCL language, tools, and applications.

                                         Keywords
                                         OCL, UML, Model-Driven Engineering, modeling languages


   The Object Constraint Language (OCL) is a popular textual notation for describing con-
straints and queries in object-oriented development. The International Workshop on OCL and
Textual Modeling is a yearly forum where the community around OCL gathers to discuss new
developments around the OCL language, valuable tools based on OCL, its applications, and
other textual modeling languages.
   The 20th International Workshop on OCL and Textual Modeling (OCL’2021) was held as a
virtual event within the Software Technologies: Applications and Foundations (STAF’2021)
federated conferences (https://staf2021.hvl.no/). All the information about the workshop is
published on the workshop’s website: https://oclworkshop.github.io/2021
   The workshop received 8 submissions, of which 7 were accepted for publication. All submitted
papers were reviewed by three members from the Program Committee:

                  • Achim D. Brucker, University of Exeter, UK
                  • Dan Chiorean, Babes-Bolyai University, Romania
                  • Tony Clark, Aston University, UK
                  • Birgit Demuth, Technische Universität Dresden, Germany
                  • Martin Gogolla, University of Bremen, Germany
                  • Frédéric Jouault, ESEO-TECh, France
                  • Sina Madani, University of York, UK
                  • Denis Nikiforov, Advalange, Russia
                  • Xavier Oriol, UPC-Barcelona Tech, Spain
OCL’2021: 20th International Workshop on OCL and Textual Modeling, June 25, 2021, Virtual Event
Envelope-Open dcalegar@fing.edu.uy (D. Calegari); rclariso@uoc.edu (R. Clarisó); ed at willink.me.uk ( (E. D. Willink)
GLOBE https://www.fing.edu.uy/~dcalegar/ (D. Calegari); https://robertclariso.github.io (R. Clarisó)
Orcid 0000-0001-9639-0186 (R. Clarisó)
                                       © 2021 Copyright for this paper by its authors. Use permitted under Creative Commons License Attribution 4.0 International (CC BY 4.0).
    CEUR
    Workshop
    Proceedings
                  http://ceur-ws.org
                  ISSN 1613-0073
                                       CEUR Workshop Proceedings (CEUR-WS.org)
    • István Ráth, Budapest University of Technology and Economics, Hungary
    • Jan Oliver Ringert, University of Leicester, UK
    • Bernhard Rumpe, RWTH Aachen, Germany
    • Ernest Teniente, UPC-Barcelona Tech, Spain
    • Antonio Vallecillo, Universidad de Málaga, Spain
    • Hao Wu, Maynooth University, Ireland

   In addition to the submitted papers, the workshop included a panel with contributions from
Dr. Jordi Cabot (ICREA), Dr. Martin Gogolla (Univ. Bremen), and Dr. Antonio Vallecillo (Univ.
Málaga). This panel focused on diagnosing the current status of OCL (language, tool ecosystem,
community, etc.) using a SWOT matrix (Strengths, Weaknesses, Opportunities, and Threats).
The key conclusions of the panel are presented in the proceedings of this workshop in the paper
“A SWOT Analysis of the Object Constraint Language”.
   Finally, two authors contributed lightning talks during the open session: “Stating the Most
General Type, not the Most Specific Type can Make Sense” by Dr. Martin Gogolla and “Normal-
izing OCL Associations” by Dr. Edward Willink.


Acknowledgments
The workshop organizers would like to thank the authors, program committee members, and
attendees for their contributions and participation in the workshop. Moreover, we would like to
thank the STAF workshop organizers (Ludovico Iovino and Lars Michael Kristensen) and STAF
organizers (Adrian Rutle) for their help in the organization of the workshop as a virtual event.