What is OPM?
Object-Process Methodology (OPM) is a conceptual modeling language for representing systems. It unifies structure and behavior in a single diagram, making complex systems easier to understand and communicate.
OPM was invented and developed by Prof. Dov Dori and is an ISO standard (ISO 19450) used across engineering, software, and business domains.
The Building Blocks
OPM uses just two fundamental elements to model any system: Objects and Processes. Everything else builds on these.
Objects & States
Objects are things that exist — physical (like a coffee cup) or informational (like an order). Objects can have states that represent their possible conditions. A rectangle represents an object, and rounded boxes inside show its states.
OPL (Object-Process Language):
Water can be cold or boiling.
Processes & Transformation
Processes are transformations — they create, consume, or change objects. An ellipse represents a process. Arrows show what goes in (consumed) and what comes out (result).
OPL (Object-Process Language):
Grinding consumes Coffee Beans and yields Ground Coffee.
State Changes
Processes can change an object's state without consuming it. The object enters the process in one state and exits in another. This is called an effect.
OPL (Object-Process Language):
Brewing changes Coffee from ground to brewed.
Enablers: Agents & Instruments
Some objects enable processes without being transformed. Agents are human enablers (shown with a filled circle). Instruments are non-human enablers like machines or tools (shown with an open circle).
OPL (Object-Process Language):
Barista handles Making Espresso. Making Espresso requires Espresso Machine.
Two Views, One Model
Every OPM model has two equivalent representations:
OPD (Diagram)
The visual representation using shapes and arrows. Great for seeing the big picture and understanding relationships at a glance.
OPL (Language)
The textual representation using structured English sentences. Precise, accessible, and easy to read without learning notation.