What is this?

xtUML Days 2020 UK is a modeling conference and represents the 7th edition of xtUML Days. (See Previous xtUML Days.) xtUML Days is the most dense gathering of Shlaer-Mellor modelers of the year. The xtUML Community meets to collaborate on Modeling, Method and Tooling.

The central topic of the conference is end-to-end modeling, execution, translation and deployment of models-as-code in mission critical settings employing rigorous methodology. The unifying theme is practical, actual, industrial application modeling within production installations. Attendees will network with engineers, scientists and educators who understand executable and translatable modeling as applied in active systems.

In 2020, a special focus will be continued to extend and clarify the Shlaer-Mellor Method in light of undocumented developments over the last several years.

Also in focus:

  • Method advances (specifically convergence of PT and K-C dialects)

  • Tooling Refinements

  • Incremental Adoption

  • Model Compilation

The xtUML Community is keen to exchange expertise and learn from one another. xtUML Days provides a forum for developers to share best practices and influence the direction of the technology. xtUML Days hereby solicits compelling papers and presentations that exhibit method advances, tooling improvements and application experience in Shlaer-Mellor modeling and related Executable/Translatable modeling. This year attendees represent One Fact, UK Crown, BAE Systems, ROGO, Northrop Grumman, Aurora Consulting, Software Improvements, L3, Thales, Toyo Corporation, ICS, FrogOOA, Kyushu University, University of Southampton and Jönköping University.

COVID-19 (Novel Coronavirus) Considerations

The conference will look much different from previous years. Your conference committee efforts will be marked by flexibility and creativity. We all hope that the world will be normal enough in November to meet face-to-face. Anticipating this, measures are being taken to apply safe meeting practices.

However, all must plan in case it travel and gathering are restricted. A virtual option is being offered in addition to the hope for physical gathering. Months of quarantine have taught us a variety of communication techniques. These will be employed in ways that allow bridging of the virtual and physical worlds. xtUML Days 2020 UK will be the best xtUML Days yet due to our growth during lockdown.

The xtUML Days planning committee is creative and has access to super techy people who know how to make virtual reality a reality. Do not think long, boring, online slideshows. Already there are plans for virtual tours, virtual panel discussions and a virtual happy hour. See Session Types below for insight into the variety of presentations. Such approaches do take some amount of preparation which we are proceeding to develop!

Keynote Speaker

Stephen Mellor

We are pleased to announce that the xtUML Days 2020 Portsmouth keynote speaker is Stephen J. Mellor, co-author of the Shlaer–Mellor Method and Executable UML, and signatory to the Agile Manifesto. Mellor has been working with methods, particularly executable methods, for real-time and embedded systems for four decades.

He explains, with clarity and humor, the intricacies of real-time and embedded systems model-driven development, in both presentations and text. He is the author of several books:

Stephen presently serves as Chief Technology Officer of the industrial internet CONSORTIUM (IIC).

Other Presenters

In addition to Stephen Mellor other key Shlaer-Mellor community members plan to participate including Colin Carter, Ian Wilkie, Leon Starr, Marc Balcer and others.



xtUML Days 2020 UK will be physically hosted at The Queens Hotel Portsmouth in Southsea, Portsmouth, UK. The hotel combines luxury and history with an ideal location situated with walking access to the shoreline, parks, restaurants and to Old Portsmouth.

xtUML Days 2020 will be virtually hosted on a platform called Hopin. Hopin is better than Zoom alone and better than YouTube alone. It emulates physical conference logistics and facilitates larger scale participation, intimate sessions and 1-on-1 meetings.


Register by emailing the chair (cortland.starrett at onefact.net). Provide name and company information. Do this even if you pay through the electronic portal below.

The registration cost is identical for both the physical and virtual event. Our virtual event platform (Hopin) will be making the virtual experience as close to a physical experience as is feasible. Interestingly, the virtual experience brings significant additional cost: camera crew, audio/visual equipment, streaming, etc.

Early registration (July/August) is $400 (USD). Early registration assures the highest likelihood of receiving the SWAG that is being prepared for all participants both physical and virtual. Virtual attendees who register early enough will receive a SWAG box shipped to their home or business address.

After August, registration is $500 (USD). Participants under contract with the Community Engagement support option attend at no cost.

Registration payment can be made with a credit card (through a PayPal portal below). Payment can be made by check. Other methods of payment can be arranged through the conference organizers. Discounts may be available to companies sending more than 3 participants; contact the chair.

Travel and Reception Dinner

Plan to arrive Wednesday evening before the conference to attend a reception dinner (included in the conference registration while space permits). Dinner will be hosted at The Still and West. A private upstairs space is reserved for xtUML Days guests. Drinks and meeting and mixing will precede (and succeed) dinner. This is a lovely pub with a view of the Harbour. (The photo at the top of the page was taken from inside The Still and West.)


Portsmouth has many hotels and Airbnb options. The xtUML Days organizers will arrange for a block of hotel rooms with a group rate at the conference venue (The Queens Hotel Portsmouth). Please check back for details!

Call for Papers

A program committee will review and select from submitted papers, posters and presentations. Selection is based upon perceived value to the xtUML Community.

Topics of interest to xtUML Days include but are not limited to the following:

  • real-world application modeling examples of installed systems

  • techniques of editing, verifying, translating, debugging and deploying models

  • methodology (Shlaer-Mellor) advances, extensions and refinements

  • static analysis of models and generated code

  • model-based model compilers

  • model integrity

  • action language dialects

  • target software architectures and translation onto those architectures

  • process integration of modeling and modeling tools

  • tooling supporting the Shlaer-Mellor Method

  • current state of the art editing, verification, translation, debugging

  • recent experience with tooling and BridgePoint in particular

  • techniques for educating modelers from young children to experienced professionals

  • tooling migration experience reports

Submit your paper, poster or presentation electronically as PDF via EasyChair. (If you are unable to submit through EasyChair, please contact the Conference Contact.) Presentations are expected to be 35-45 minutes in duration including time for questions and discussion.

All submissions will be evaluated by the program committee. Selection is based upon significance, clarity and alignment with the call and value to the attendees of xtUML Days 2020 UK. Submissions that promote discussion, advance the Method and generate interaction among xtUML Community members are most desired. For a presentation to be accepted, at least one of the authors must register for xtUML Days, present the material and participate in the conference.

Important Dates

  • Title, session type and duration submission: 31 July 2020

  • Abstract submission deadline: 15 August 2020

  • Author notification: 30 September 2020 (but likely shortly after abstract is submitted)

  • Submission deadline for presentation-ready version: 22 October 2020

  • xtUML Days conference: 5 November 2020

Conference Format

Day 1 of xtUML Days is an information dense and interactive conference lasting one full day. The host will welcome attendees at the starting hour. The host will make significant introductions. Key xtUML Community members will give short updates on their applications and experiences. Presentations with Q&A and discussions will fill the morning and afternoon sessions. An open moderated discussion time will end the day.

A detailed agenda will be available in October upon solidification of the speaking agenda.

A day 2 of xtUML Days is a planning day for active members of the xtUML Community. Planning Day is focused on short and long term requirements of the Method and road map for tooling. Day 2 attendance is by invitation only.

Session Types

For virtual, mixed physical/virtual and even physical-only conferences, variety is a key to engagement. Various flavors of session are defined here.

All session types are eligible to be pre-recorded. For pre-recorded sessions, the presenter will be available live (locally or remotely) to respond to questions and comments.

Table 1. Session Types
Session Type Abbrev # time Description

keynote presentation




classic featured presentation from featured expert

technical presentation




These are traditional full length presentations from recognized experts in the field. Together with the experience reports, these represent the primary content of the conference.

experience report




Experience reports are medium length presentations focused on the application of modeling in industry or education.

panel discusion




The panel discussion typically involves a moderator and a panel of experts. Questions have been prepared and shared with panel members. Audience participation is included.





A debate doubles as a networking activity. Participants are assigned to groups. Each group is given a position statement to debate. After the debate time, summary statements are presented by a moderator.

networking activity




These activities are pre-arranged, potentially moderated, topical and focused on connecting participants. Techniques to bridge local and remote are to be prepared.





interactive interview of person of interest focusing on the role that makes the person special to the xtUML community

tool/app demonstration




demonstration of a new feature or procedure in the tooling (ASL editor, Ciera, OOA of MASL, canvas features, Carpark)

company expo




To showcase participant companies and organizations, these will work best as pre-recorded production videos.





personal introduction answering a few key questions (name, profession, organization, key connection with xtUML) in a pre-recorded format

video tour




1-5 minute video tour of venue or point of interest to the xtUML community (Queens venue, Portsmouth, HMS Victory, MatchBOX)

happy hour




Happy hour is an organized tasting and sharing of a beverage together. It is fun to have a brewmeister or distiller present to explain and teach and connect those participating online.

Conference Organization

  • Cortland Starrett, Conference Chair, One Fact, USA, cortland.starrett [at] onefact.net

  • Dave Skinner, Host Committee Member, BAE Systems, UK

  • Dave Salt, Program Committee Member, UK Government, UK

  • Emily Carter, Conference Coordinator, Change Agent Studio LLC, USA

Conference Contact

If you have questions about xtUML Days 2020 UK, contact the Chair via email at: cortland.starrett [at] onefact.net or the Conference Coordinator via email at: emily.carter [at] onefact.net.