A First Model

This page walks through the smallest meaningful Primmel model line by line. By the end, you will recognize every construct that appears in larger real-world models.

The header

Every model begins with three things: a root, a version, and a metadata block.

root HelloWorld

version "v1.0.0-dev1"

metadata {
  title "Minimal Primmel model"
  schema "Primmel 0.1"
  edition "1"
  author "Primmel project"
  shortname "HelloWorld"
  namespace "HelloWorld"
}

Roles

Roles describe who does the work. A role has an ID and a human-readable name.

role Org {
  name "Organization"
}

role Greeter {
  name "Greeter"
}

Org is a conventional ID for the generic organization-wide role (matching real-world models). Greeter is a more specific role that we will assign to a process below.

Events

A process flow has a beginning and an end. Both are events:

start_event Start1 { }
end_event   End1   { }

A model with multiple canvas diagrams has multiple start_events — one per canvas. This is normal: each diagram needs its own entry point.

Processes

A process is a unit of work performed by a role:

process Greet {
  name "Greet the world"
  actor Greeter
}

The actor clause binds the process to a role. At evaluation time, this is how tooling determines whose responsibility the step is.

A real-world process usually also has:

• modality SHALL / SHOULD / MAY — the compliance weight of the step.
• validate_provision { ... } — the provisions this process must satisfy. See example 04.
• reference_data_registry { ... } — data registries this process reads from.
• output { ... } — data registries this process writes to.

The canvas

A canvas is a container that lays out a flow. The header named HelloWorld as the root; now we define it:

canvas Root {
  elements {
    Start1 { x 0  y 0 }
    Greet  { x 0  y 100 }
    End1   { x 0  y 200 }
  }
  process_flow {
    Edge1 { from Start1  to Greet }
    Edge2 { from Greet   to End1 }
  }
  data { }
}

A canvas has three blocks:

The Root canvas is the top-level flow. A model with multiple canvases names them like pages (OrderFlow, QualityCheckFlow, SupplierReviewFlow) — see example 03 and the implementation package.

What this model lacks

The minimal model is correct Primmel, but it does not exercise:

• Data — no class, enum, or data_registry. Added in example 02.
• Compliance — no provision or reference. Added in example 04.
• Branching — no exclusive_gateway. Added in example 03.
• Mapping — no map_profile or .prm file. Added in the implementation package.

That is what the rest of the example corpus adds, one primitive at a time.

Next

Open the examples index and pick the next file in the reading order. Each example introduces one new primitive group, with the relevant lines highlighted and explained.