Scripts.md

Scripts

Inline scripts handler interface.

• Scripts
  • register(activity): register script
  • getScript(scriptType, activity): get registered script
    • execute(executionContext, callback)

register(activity)

Register script. Called from activity behaviour.

Arguments:

• activity: activity instance

getScript(scriptType, activity)

Get registered script. Called from activity behaviour when executing.

Arguments:

• scriptType: script type from definition
• activity: activity with script

Must return interface with one required function that is named execute.

The execute function will receive an execution context and a callback that should be called when the execution is completed.

Example implementation for nodejs

import { Script } from 'vm';

export function Scripts() {
  const scripts = {};

  return {
    getScript,
    register,
  };

  function register({ id, type, behaviour, environment }) {
    let scriptBody, language;

    switch (type) {
      case 'bpmn:SequenceFlow': {
        if (!behaviour.conditionExpression) return;
        language = behaviour.conditionExpression.language;
        if (!language) return;
        scriptBody = behaviour.conditionExpression.body;
        break;
      }
      default: {
        language = behaviour.scriptFormat;
        scriptBody = behaviour.script;
      }
    }

    if (!/^javascript$/i.test(language)) return;

    const script = new JavaScript(language, `${type}/${id}`, scriptBody, environment);
    scripts[id] = script;

    return script;
  }

  function getScript(language, { id }) {
    return scripts[id];
  }
}

function JavaScript(language, filename, scriptBody, environment) {
  this.id = filename;
  this.script = new Script(scriptBody, { filename });
  this.language = language;
  this.environment = environment;
}

JavaScript.prototype.execute = function execute(executionContext, callback) {
  const timers = this.environment.timers.register(executionContext);
  return this.script.runInNewContext({ ...executionContext, ...timers, next: callback });
};