xtUML Days 2019 In Motion

The conference has come and gone. We had a great mix of practitioners, methodologists, educators and fans. The week started with a reception dinner where we had an excellent menu and an upstairs room to ourselves. The conference proper featured presentations, debates and a panel discussion. Pictured here is the keynote speaker, Takao Futagami. Expect […]

xtUML Days next week…


xtUML Days is next week! The conference promises to be everything hoped. The line-up of presentations is compelling. However, the most exciting aspect of the conference is the rich list of attendees from 15 different companies and universities represented from 4 continents!

Shlaer-Mellor Runtime


Stephen and Sally never supplied a pre-packaged “Shlaer-Mellor Runtime Engine” in the form of operating system or middleware services. Instead, they defined rules for the execution of domains modeled using the Shlaer-Mellor Method. Examples included the Time and Event Rules, such as, “Event ordering shall be maintained between sender/receiver pairs.” (Which tacitly implies that ordering […]

Keynote Speaker

The xtUML Days 2019 UK keynote speaker is Takao Futagami. He is a chief consultant at Toyo Corporation. His research interests focus on embedded systems engineering. Futagami-sensei holds a degree in physics from Tsukuba University and is a professor at Tokai University. Mr. Futagami was instrumental to the introduction of the Shlaer-Mellor Method, xtUML and […]

Find a Bug; Fix a Bug

We develop software. New functionality is added. It is tested. Bugs are found, and bugs are fixed. Here is a candid dialogue on a recent chat regarding a bug that escaped our release testing but was found quickly (and is now fixed). —Heads up. We have discovered an annoying issue with the new association editor. […]

xtUML Days 2019 UK (1)

xtUML Days 2019 UK is coming September 12 in Cheltenham. This is the 6th edition of xtUMLDays. Last year xtUML Days hosted a substantial contingent of Shlaer-Mellor expertise from Saab, Vricon, UK Govt, ICS, BAE Systems, Kyushu University and others. This year will introduce new members to the modeling community. The information page is here: […]


In the automotive sector, AUTOSAR establishes standards for architecture, communication and deployment for software and sensor/actuator functionality. A model-driven development approach enables the generation of many of the required artifacts encoded as ARXML. Here is a PhD thesis describing formal verification of such a system.

Saab Coming to West Lafayette


Various divisions within Saab have been long-time practitioners of executable modeling.  Today it was announced that Saab will be opening a site in the USA next door to Purdue University and One Fact headquarters! Saab Press Release Saab ‘Journey to West Lafayette‘ Purdue University Press Release West Lafayette Local Reporting

State Diagram, State Table


The state transition diagram is a graphical representation of a finite state machine in an executable UML model.  The states are the rounded boxes; transitions are the arrows between.  Events label the transitions, and activities can be expressed as action language in the states or on the transitions. A state event matrix (or state transition […]