page_title: Object Process Methodology
section_title: Links
hierarchical_section_title: Object Process Methodology / Basics / Links
caption_attribution_description: English: OPM Procedural Links
context_page_description: Object Process Methodology is a conceptual modeling language and methodology for capturing knowledge and designing systems, specified as ISO/PAS 19450. Based on a minimal universal ontology of stateful objects and processes that transform them, OPM can be used to formally specify the function, structure, and behavior of artificial and natural systems in a large variety of domains.
  OPM was conceived and developed by Dov Dori. The ideas underlying OPM were published for the first time in 1995. Since then, OPM has evolved and developed.
  In 2002, the first book on OPM was published, and on December 15, 2015, after six years of work by ISO TC184/SC5, ISO adopted OPM as ISO/PAS 19450. A second book on OPM was published in 2016.
  Since 2019, OPM has become a foundation for a Professional Certificate program in Model-Based Systems Engineering - MBSE at EdX. Lectures are available as web videos on Youtube.
context_section_description: Structural link
  A structural links defines a structural relation. A structural relation shall specify an association that persists in the system for at least some interval of time.
  Procedural link
  A procedural link defines procedural relation. A procedural relation shall specify how the system operates to attain its function, designating time dependent or conditional triggering of processes, which transform objects.
  Event and condition
  The Event-Condition-Action paradigm provides the OPM operational semantics and flow of control. An event is a point in time at which an object is created (or appears to be created from the system's perspective) or an object enters a specified state. At runtime, this process triggering initiates evaluation of the process precondition. Thus, starting a process execution has two prerequisites: (1)  a triggering event, and (2) satisfaction of a precondition.
  Once the event triggers a process, the event ceases to exist. The precondition is the existence of the required object instances in the preprocess object set, possibly in specific states, as modeled. If and only if the evaluation reveals satisfaction of the precondition, the process starts executing.
caption: OPM procedural links
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