Missing label validation for gateway

[danielriedmueller]

Describe the Bug

If a gateway has two inputs and one output and no label,
it shows no error.

Expected Behavior

All gateways must have a label, regardless of connections.
Its expected that the linter shows an error.

BMPN to reproduce:

<?xml version="1.0" encoding="UTF-8"?>
<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">
  <bpmn:process id="Process_1" isExecutable="false">
    <bpmn:startEvent id="StartEvent_1" name="a">
      <bpmn:outgoing>Flow_00fqd4a</bpmn:outgoing>
    </bpmn:startEvent>
    <bpmn:exclusiveGateway id="Gateway_07ubf6j">
      <bpmn:incoming>Flow_0o5mpbt</bpmn:incoming>
      <bpmn:incoming>Flow_15iaxbt</bpmn:incoming>
      <bpmn:outgoing>Flow_19faper</bpmn:outgoing>
    </bpmn:exclusiveGateway>
    <bpmn:endEvent id="Event_1qe3417" name="c">
      <bpmn:incoming>Flow_19faper</bpmn:incoming>
    </bpmn:endEvent>
    <bpmn:sequenceFlow id="Flow_00fqd4a" sourceRef="StartEvent_1" targetRef="Gateway_0oz6smg"/>
    <bpmn:sequenceFlow id="Flow_19faper" sourceRef="Gateway_07ubf6j" targetRef="Event_1qe3417"/>
    <bpmn:exclusiveGateway id="Gateway_0oz6smg" name="gateway label">
      <bpmn:incoming>Flow_00fqd4a</bpmn:incoming>
      <bpmn:outgoing>Flow_0o5mpbt</bpmn:outgoing>
      <bpmn:outgoing>Flow_1ubb3cz</bpmn:outgoing>
    </bpmn:exclusiveGateway>
    <bpmn:sequenceFlow id="Flow_0o5mpbt" sourceRef="Gateway_0oz6smg" targetRef="Gateway_07ubf6j"/>
    <bpmn:task id="Activity_14jxjwd" name="b">
      <bpmn:incoming>Flow_1ubb3cz</bpmn:incoming>
      <bpmn:outgoing>Flow_15iaxbt</bpmn:outgoing>
    </bpmn:task>
    <bpmn:sequenceFlow id="Flow_1ubb3cz" sourceRef="Gateway_0oz6smg" targetRef="Activity_14jxjwd"/>
    <bpmn:sequenceFlow id="Flow_15iaxbt" sourceRef="Activity_14jxjwd" targetRef="Gateway_07ubf6j"/>
  </bpmn:process>
  <bpmndi:BPMNDiagram id="BPMNDiagram_1">
    <bpmndi:BPMNPlane id="BPMNPlane_1" bpmnElement="Process_1">
      <bpmndi:BPMNShape id="_BPMNShape_StartEvent_2" bpmnElement="StartEvent_1">
        <dc:Bounds x="173" y="92" width="36" height="36"/>
        <bpmndi:BPMNLabel>
          <dc:Bounds x="188" y="135" width="7" height="14"/>
        </bpmndi:BPMNLabel>
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Gateway_0oz6smg_di" bpmnElement="Gateway_0oz6smg" isMarkerVisible="true">
        <dc:Bounds x="255" y="85" width="50" height="50"/>
        <bpmndi:BPMNLabel>
          <dc:Bounds x="246" y="55" width="68" height="14"/>
        </bpmndi:BPMNLabel>
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Gateway_07ubf6j_di" bpmnElement="Gateway_07ubf6j" isMarkerVisible="true">
        <dc:Bounds x="345" y="85" width="50" height="50"/>
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Event_1qe3417_di" bpmnElement="Event_1qe3417">
        <dc:Bounds x="432" y="92" width="36" height="36"/>
        <bpmndi:BPMNLabel>
          <dc:Bounds x="447" y="135" width="6" height="14"/>
        </bpmndi:BPMNLabel>
      </bpmndi:BPMNShape>
      <bpmndi:BPMNShape id="Activity_14jxjwd_di" bpmnElement="Activity_14jxjwd">
        <dc:Bounds x="230" y="210" width="100" height="80"/>
        <bpmndi:BPMNLabel/>
      </bpmndi:BPMNShape>
      <bpmndi:BPMNEdge id="Flow_00fqd4a_di" bpmnElement="Flow_00fqd4a">
        <di:waypoint x="209" y="110"/>
        <di:waypoint x="255" y="110"/>
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge id="Flow_19faper_di" bpmnElement="Flow_19faper">
        <di:waypoint x="395" y="110"/>
        <di:waypoint x="432" y="110"/>
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge id="Flow_0o5mpbt_di" bpmnElement="Flow_0o5mpbt">
        <di:waypoint x="305" y="110"/>
        <di:waypoint x="345" y="110"/>
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge id="Flow_1ubb3cz_di" bpmnElement="Flow_1ubb3cz">
        <di:waypoint x="280" y="135"/>
        <di:waypoint x="280" y="210"/>
      </bpmndi:BPMNEdge>
      <bpmndi:BPMNEdge id="Flow_15iaxbt_di" bpmnElement="Flow_15iaxbt">
        <di:waypoint x="330" y="250"/>
        <di:waypoint x="370" y="250"/>
        <di:waypoint x="370" y="135"/>
      </bpmndi:BPMNEdge>
    </bpmndi:BPMNPlane>
  </bpmndi:BPMNDiagram>
</bpmn:definitions>

[nikku]

@danielriedmueller Why would a joining gateway need a label? What would be the user problem this solves?

[nikku]

Closing this as not planned, but happy to hear your thoughts to learn.

[danielriedmueller]

Thanks for your response, that makes sense.
However in our project, we need to have each elements have labels and these labels need to be unique.
I made a proposal for a rule for unique labels: bpmn-io/bpmnlint#153.
We would have preferred to use a official rule from your side, but i guess we can implement our own rules as well.

[nikku]

We've seen and discussed bpmn-io/bpmnlint#153. As we evolve our rule set and do more "at the core" we have to ensure to provide value to many. Your scenario "all elements have to be named" seems to be special. And completely (everywhere) enforcing unique labels does not make sense from the pure BPMN standpoint, too.

What bpmnlint offers is the ability to configure rules. So we could build (or you could contribute) changes that are configurable, but work per default in a reasonable (for many) way.