Object-centric Process Mining Model

QPR ProcessAnalyzer supports object-centric process mining (OCPM) based on the OCEL 2.0 standard (https://www.ocel-standard.org). To use object-centric functionality, you need to transform data into the suitable format for the object-centric model. Object-centric models can be analyzed in the object-centric flowchart and with (case-centric) charts because the object-centric model can be converted into a case-centric eventlog using perspectives. To use the OCPM functionality, Snowflake needs to be used as the calculation engine.

Create object-centric model

Create a new object-centric model as follows:

1. In the Workspace, open the project where to create the model.
2. Select NEW" in the top right menu and select model.
3. Define a name for the new model.
4. Set Model type as Object-centric.
5. Click Create.

Configure object-centric model datatables

Datatables for the object-centric model need to exist in the same project as the model. Datatables can be set for the model as follows:

1. In the Workspace, select the object-centric model and click Properties.
2. In the model properties dialog, open the Datasource tab.
3. Add a following kind of json configuration to the textbox:

{
  "Objects": "OCPM: objects",
  "Events": "OCPM: events",
  "ObjectToObject": "OCPM: object-object",
  "EventToObject": "OCPM: event-object",
  "ObjectTypes": {
    "Invoice": "OCPM object: Invoice",
    "Payment": "OCPM object: Payment",
    "Purchase Order": "OCPM object: Purchase Order"
  },
  "EventTypes": { 
    "Approve Purchase Requisition": "OCPM event: Approve Purchase Requisition",
    "Change PO Quantity": "OCPM event: Change PO Quantity",
    "Create Purchase Order": "OCPM event: Create Purchase Order",
    "Insert Invoice": "OCPM event: Insert Invoice",
    "Insert Payment": "OCPM event: Insert Payment"
  }
}

The json configuration needs to have following properties:

• Objects: Objects datatable name.
• Events: Events datatable name.
• ObjectToObject: Object-to-object relation datatable name.
• EventToObject: Event-to-object relation datatable name.
• ObjectTypes: Key-value-pairs of object type datatable names. Note that object names need to match with object names in the objects datatable.
• EventTypes: Key-value-pairs of event type datatable names. Note that event names need to match with event names in the events datatable.

Import from OCEL 2.0 JSON file

Object-centric model can be import from an OCEL 2.0 JSON file as follows:

1. In the Workspace, open the project where to import the model.
2. Select NEW in top right menu and select Import Model.
3. Select the OCEL 2.0 JSON file from the disk and click Open.

An object-centric model and a list of datatables is created.

Example OCEL 2.0 eventlogs: https://www.ocel-standard.org/event-logs/overview/ (download the json format supported by QPR ProcessAnalyzer)

Object-centric model structure

Object-centric model contains datatables described in the table below. Datatables can be named freely, as the model json configuration is used to define the datatable for each type of data. The datatables need to use column names specified in the table below because those are the column names assumed by the object-centric (i.e., column names cannot be selected freely).

Datatable role	Contained data	Datatable columns
Objects	Objects in the model (one row per object).	OcelObjectId: Unique id for the object (among all objects in the model). OcelObjectType: Object type name (such as Order, Invoice, Delivery). Note that the model json configuration need to use same object type names.
Events	Events in the model (one row per event).	OcelEventId: Unique id for the event (among all events in the model). OcelEventType: Event type name (such as Order created, Invoice sent). Note that the model json configuration need to use same event type names. OcelEventTime: Event timestamp.
Object-object relations	Relations between objects (one row per relation).	OcelObjectToObjectSourceId: Source object id in the relation. OcelObjectToObjectTargetId: Target object id in the relation. OcelObjectToObjectQualifier: Describes the type of the relation as free-form text (not used currently).
Event-object relations	Relations between events and objects (one row per relation).	OcelEventToObjectSourceId: Object id in the relation. OcelEventToObjectTargetId: Event id in the relation. OcelEventToObjectQualifier: Describes the type of the relation as free-form text (not used currently).
Object attributes (several datatables)	Object attribute values, each object type in a separate table (one row per object).	OcelObjectTypeObjectId: Object id. Matches to the objects datatable OcelObjectId column. OcelObjectTypeTime: Timestamp which the attribute value is valid from (not used currently). OcelObjectTypeChangedField: Changed object attribute name (not used currently). <Object attributes>: Columns for each of the object attribute values (column name is the object attribute name).
Event attributes (several datatables)	Event attribute values, each event type in a separate table (one row per event).	OcelEventTypeEventId: Event id. Matches to the events datatable OcelEventId column. <Event attributes>: Columns for each of the event attribute values (column name is the event attribute name).

Object-centric perspectives

Perspectives convert an object-centric model into the traditional case-centric eventlog, allowing to view and analyze object-centric models in analyses provided by charts. A single perspective is not able describe the object-centric model entirely, but just from a certain limited viewpoint. By using analyses with several perspectives, it's possible to get a more complete picture of the object-centric model. The perspective starts from a certain object type and traverses the object-object relations as many steps as desired.

To define a perspective, the following settings are defined in the chart settings:

• Base Object type: Object of this type will be cases in the projected case-centric eventlog.
• Object Relation Steps: Specifies how many object-object relations will be traversed in order to find events connected to the base objects. Value zero means that only those events are returned that are directly connected to the base objects.
• Show Event Types: List of event type names which are included into the perspective eventlog. If no events are explicitly defined, all events will be included, but their event attributes are not included.

The resulting perspective eventlog will have the following columns:

• OcelObjectId (mapped to case id)
• OcelEventType (mapped to event type)
• OcelEventTime (mapped to timestamp)
• OcelEventId
• Object attributes of the base object type. Note that the object attribute values are "repeated" for all events belonging to the same object.
• Event attributes of the selected event types. Values are null for events that don't have the attribute.

The base object type attributes are available as case attributes. As the object attribute values may change over time in the OCEL 2.0 data, the last attribute value is used as the case attribute value. Note that other object type's attributes are not available as case attributes, so the object for which the attributes are used, need to be set as the base object.

Save perspective to filter

It's possible to include the object-centric perspective to a stored filter. When a filter is selected, also the perspective in the filter is applied to the dashboard. This allows to quickly change perspectives for the entire dashboard. The chart specific perspective overrides the dashboard level perspective, so the dashboard level perspective is only applied for charts that don't have the chart specific perspective defined.

Perspective can be added to a filter as follows:

1. Go to the Process Discovery dashboard.
2. Open the Session variables dialog in the dots menu on top right.
3. Paste the filter json to the Value of the Filter variable (it might be easiest to start with a filter without filter rules, and then add the filter rules using the UI).
4. Click Done button for the dialog.
5. Save the filter by hovering the Unsaved filter (filters dropdown list) in the header and click Save as new filter.

Example: Filter json without any filter rules:

{
  "Items": [],
  "Perspective": {
    "ObjectType": "Container",
    "RecursionDepth": 0
  }
}

Example: Filter json with a filter rule:

{
  "Items": [
    {
      "Type": "IncludeEvents",
      "Items": [
        {
          "Type": "Attribute",
          "Attribute": "OcelEventId",
          "StringifiedValues": [ "0Event 1" ]
        }
      ]
    }
  ],
  "Perspective": {
    "ObjectType":  "Container",
    "RecursionDepth": 0
  }
}

Differences to OCEL 2.0 standard

Object-centric models in QPR ProcessAnalyzer are mainly following the OCEL 2.0 standard, but there are the following differences:

• Changing of object attributes values over time is not supported.
• ocel_time field of each event type table is moved to events datatable (as every event has a timestemp).
• *_map_type columns are not needed as the model settings are used for the same purpose.
• Object type tables: If OcelObjectTypeChangedField is not null, all the other field values are copied from the previous entry except:
  • OcelObjectTypeChangedField which has the names of the changed fields as a comma separated string.
  • The actual changed field which has the new value.
  • OcelObjectTypeTime which has the timestamp when the value changed.