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Description of the file format used for saving Petri net

JSON file format has been chosen for saving Petri net. This was initially made to be compatible with pnet-simulator but the format is no longer compatible. Here, is an example of its content:

{
  "revision": 3,
  "type": "Timed Petri net",
  "nets": [
    {
       "name": "Hello World",
       "places": [
            { "id": 0, "caption": "P0", "tokens": 1, "x": 184, "y": 295 },
            { "id": 1, "caption": "P1", "tokens": 0, "x": 513, "y": 295 }
       ],
       "transitions": [
            { "id": 0, "caption": "T0", "x": 351, "y": 295, "angle": 0 }
       ],
       "arcs": [
            { "from": "P0", "to": "T0" },
            { "from": "T0", "to": "P1", "duration": 3 },
            { "from": "T0", "to": "P0", "duration": 1 }
       ]
    }
  ]
}

Json file has revison number concerning its syntax (currently version 3). Currently only an array with a single net is loaded ("nets": [ { ... ] ]).

A Petri net is composed of three arrays (the [ ]): Places, Transitions and Arcs. In this example, is stored in the JSON file a Petri net made of two places, one transition, and two arcs.

Places and Transitions:

  • their unique identifier (unsigned int) i.e. 0, 1. All ids shall be consecutive (no holes).
  • their caption is a string with spaces accepted.
  • their X and Y coordinate (float) in the screen i.e. T0 is placed at (351,295).
  • for places only: the number of tokens they hold (zero or positive number) i.e. P1 has 0 tokens while P0 has a single token.
  • for transition only: the angle (in degree) of rotation when displayed.

Arcs:

  • re directed links between two nodes of the different types (i.e. the first arc in this example, links the origin place P0 to the destination transition T0). Therefore an arc cannot link two places or link two transitions.
  • have no identifiers because the pair origin and destination nodes make them unique.
  • has a unit of time (positive value) i.e. the arc T0 --> P1 has 3 units of times (float). This time is only used for arc Transition to Place this means that for arc Place to Transition this value is not used.

Net:

  • Have a name (here "Hello World") and is typed of "Timed Petri net" or .