BPMN-Sol

BPMN-Sol is a compiler to convert BPMN 2.0 xml to solidity smart contract.

Changes in the new version

Previously, with the version v0.0.3 of the bpmn-sol it was not possible to compile a business process model with multiple XOR gateways and multiple script tasks. When tried to compile such a diagram, the user would get a compilation error.

Now with the new version v1.0 the functionality to compile a business process model with multiple script tasks and gateways is supported. This comes with an additional requirement with respect to modelling the diagram. Please find below the modelling requirements.

Modelling Requirements

In order to support the compilation of a business process model with multiple script tasks or multiple gateways, the bpmn-sol compiler expects the diagrams to be modelled in a specific way.

• All the gateways should be named. If the gateway is not named then the compiler assigns the id of the node to the gateway. But it is encouraged to name the gateways.
• All the sequence flows emerging out a gateway has to be named. This is highly important for the compiler to parse the diagram. Failure to specify the names for the sequence flows emerging out of the gateway will result in compilation error.

Installation

To install the package run the following command.

npm install bpmn-sol

You can require the package by using

const compiler = require('bpmn-sol)

Usage

The BPMN 2.0 xml can be converted to solidity using the compile() function. The xml to be passed should be an object with the xml value and a name for the smart contract. It has to be in below format.

const xml = {
  bpmn: '<?xml version="1.0" encoding="UTF-8"?>\n<bpmn:definitions xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:bpmn="http://www.omg.org/spec/BPMN/20100524/MODEL" xmlns:bpmndi="http://www.omg.org/spec/BPMN/20100524/DI" xmlns:dc="http://www.omg.org/spec/DD/20100524/DC" xmlns:di="http://www.omg.org/spec/DD/20100524/DI" id="Definitions_1" targetNamespace="http://bpmn.io/schema/bpmn">\n  <bpmn:process id="Process_0" name="Process_0" isExecutable="false">\n    <bpmn:startEvent id="StartEvent_1">\n      <bpmn:outgoing>SequenceFlow_005ctt4</bpmn:outgoing>\n    </bpmn:startEvent>\n    <bpmn:task id="Task_1hm78g6" name="a">\n      <bpmn:incoming>SequenceFlow_005ctt4</bpmn:incoming>\n      <bpmn:outgoing>SequenceFlow_06osrd7</bpmn:outgoing>\n    </bpmn:task>\n    <bpmn:sequenceFlow id="SequenceFlow_005ctt4" sourceRef="StartEvent_1" targetRef="Task_1hm78g6" />\n    <bpmn:endEvent id="EndEvent_1rfz6w8">\n      <bpmn:incoming>SequenceFlow_06osrd7</bpmn:incoming>\n    </bpmn:endEvent>\n    <bpmn:sequenceFlow id="SequenceFlow_06osrd7" sourceRef="Task_1hm78g6" targetRef="EndEvent_1rfz6w8" />\n  </bpmn:process>\n  <bpmndi:BPMNDiagram id="BPMNDiagram_1">\n    <bpmndi:BPMNPlane id="BPMNPlane_1" bpmnElement="Process_0">\n      <bpmndi:BPMNShape id="_BPMNShape_StartEvent_2" bpmnElement="StartEvent_1">\n        <dc:Bounds x="173" y="102" width="36" height="36" />\n      </bpmndi:BPMNShape>\n      <bpmndi:BPMNShape id="Task_1hm78g6_di" bpmnElement="Task_1hm78g6">\n        <dc:Bounds x="275" y="80" width="100" height="80" />\n      </bpmndi:BPMNShape>\n      <bpmndi:BPMNEdge id="SequenceFlow_005ctt4_di" bpmnElement="SequenceFlow_005ctt4">\n        <di:waypoint xsi:type="dc:Point" x="209" y="120" />\n        <di:waypoint xsi:type="dc:Point" x="275" y="120" />\n        <bpmndi:BPMNLabel>\n          <dc:Bounds x="242" y="98" width="0" height="13" />\n        </bpmndi:BPMNLabel>\n      </bpmndi:BPMNEdge>\n      <bpmndi:BPMNShape id="EndEvent_1rfz6w8_di" bpmnElement="EndEvent_1rfz6w8">\n        <dc:Bounds x="427" y="102" width="36" height="36" />\n        <bpmndi:BPMNLabel>\n          <dc:Bounds x="445" y="141" width="0" height="13" />\n        </bpmndi:BPMNLabel>\n      </bpmndi:BPMNShape>\n      <bpmndi:BPMNEdge id="SequenceFlow_06osrd7_di" bpmnElement="SequenceFlow_06osrd7">\n        <di:waypoint xsi:type="dc:Point" x="375" y="120" />\n        <di:waypoint xsi:type="dc:Point" x="427" y="120" />\n        <bpmndi:BPMNLabel>\n          <dc:Bounds x="401" y="98" width="0" height="13" />\n        </bpmndi:BPMNLabel>\n      </bpmndi:BPMNEdge>\n    </bpmndi:BPMNPlane>\n  </bpmndi:BPMNDiagram>\n</bpmn:definitions>\n',
  name: 'Sample_contract'
}

When this object is passed to the compile() function it returns an object with three values Solidity code,ByteCode, ABI

For example

const contract = compiler.compile(xml).then(contract => {
 console.log(contract);
})

This logs the output object.

Acknowledgments

The BPMN-Sol is utilizing/forking the compiler of the Caterpillar engine. We thank the Caterpillar creator for his great work.

Contribution

Contributions are welcome. Make sure you run the tests before creating a pull request and add test cases that cover the contributed code.

To build bpmn-sol from its source files run npm run build.

Authors

• Gowtham Mohan
• Timotheus Kampik