English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

State machines are used ubiquitously in engineering software-intensivesystems. UML State Machines extend simple finite state machines with powerfulconstructs. Among the many extensions, there is one seemingly simple andinnocent language construct that fundamentally changes state machines' reactivemodel of computation: doActivity behaviors. DoActivity behaviors describebehavior that is executed independently from the state machine once entered ina given state, typically modeling complex computation or communication asbackground tasks. However, the UML specification or textbooks are vague abouthow the doActivity behavior construct should be appropriately used. This lackof guidance is a severe issue as, when improperly used, doActivities can causeconcurrent, non-deterministic bugs that are especially challenging to find andcould ruin a seemingly correct software design. The Precise Semantics of UMLState Machines (PSSM) specification introduced detailed operational semanticsfor state machines. To the best of our knowledge, there is no rigorous reviewyet of doActivity's semantics as specified in PSSM. We analyzed the semanticsby collecting evidence from cross-checking the text of the specification, itssemantic model and executable test cases, and the simulators supporting PSSM.We synthesized insights about subtle details and emergent behaviors relevant totool developers and advanced modelers. We reported inconsistencies and missingclarifications in more than 20 issues to the standardization committee. Basedon these insights, we studied 11 patterns for doActivities detailing theconsequences of using a doActivity in a given situation and discussingcountermeasures or alternative design choices. We hope that our analysis of thesemantics and the patterns help vendors develop conformant simulators orverification tools and engineers design better state machine models.

To Do or Not to Do: Semantics and Patterns for Do Activities in UML PSSM State Machines