Entities

There are three types of entities available:

• Root entity: They are the only entry point to an encapsulated cluster of entities. A root entity has its own lifecycle (creation/life/deletion), contains a unique ID, properties and can persist in / delete from a database collection.

• Entity: They are simple value entities without an ID, containing properties that can be connected to a root entity as a local entity. They can also be used as input/output for commands and services as well as payload to events. This type of entity will not be persisted.

• External entity: They are used to mapping and interacting with another entity from an external source which was integrated and modelled in an integration namespace. Since they represent a pointer to an entity that resides in another domain/system, they don't have to contain all definitions of the original external entity, just some identifier properties that help loading the external entity from wherever it resides through the external entity's load functionality. It can also contain its own properties.

See also introduction to Domain Driven Design for further details.

You can access an overview page of the existing entities by visiting the entities tab on the domain namespace's Overview page. You can create a new entity by using the Create capability.

You can also import an entity by using the Import button on the entities tab at the Overview page of a domain namespace.

1. Select service:

Select the instance of IBM Cloud Pak for Data from which you like to import entities. IBM Cloud Pak instances can be added and managed in the Admin Settings on the Cloud Pak Services tab (currently only IBM Cloud Pak for Data is supported).

2. Select catalog:

Select a catalog of the IBM Watson® Knowledge Catalog from which you like to import.

3. Select data asset:

Now select the Data Asset you like to use for generation of an entity. The table shows name, tags and rating of the assets which have been specified in the IBM Watson® Knowledge Catalog. It is only possible to select one data asset at a time.

4. Select properties:

After selecting a data asset and clicking on Next, the wizard shows all available properties of the selected data asset. There you can select one, many or all properties to be associated with the new entity. You can edit the name and choose the data type of each property and also set it as a required field or not.

But before, you have to decide what type of entity you want to create. It is also required to give the entity a name, a label and at least one associated property. After clicking on the Import button the new entity will be created.

Field description:

• Type: This is used to specify the type of the entity (required)

• Local Identifier: This is the local identifier (name) of the entity. It is unique within a namespace. Please note that only the characters A-z (without special characters), digits and the special character "_" are permitted for naming entities! Furthermore, local identifiers may not begin with a digit and the first character must be uppercase. The local identifier cannot be changed after creation (required)

• Label: This is used to name the entity (required)

• Short Label: This is used to give an even shorter label (optional)

• Available Properties: This is used to add properties to the entity. These properties have been specified in the IBM Watson® Knowledge Catalog and can now get adjusted in that table. Name, type, association, and origin type are shown in the table while name, type and association can also be edited in the table. Multiple properties can be selected for import but at least one has to be selected

You can edit the master data of all entity types by using the Information capability on an entity's instance page, navigating to the Master Data section and using the Edit capability. Alternatively, you can use the Edit capability at each row of the table on the entities tab of a domain namespace's Overview page.

You can only edit the following fields:

• Label

• Short Label

• Notes

• Abstract (only for entities and root entities)

You can delete an entity by using the Information capability on an entity's instance page, navigating to the Master Data section and using the Delete capability. Alternatively, you can use the Delete capability at each row of the table on the entities tab of a domain namespace's Overview page.

You can assign any number of parent entities while creating entities or root entities. It is also possible to add parents after creation in the Parents section of the Details view. Each entity for which a parent was assigned is called a child of the parent entity. All children inherit Properties and Commands from their parents. You can use the Remove capability to remove the assignment of a parent to an entity within the Details view as well.

You can associate new or existing properties to the entity by navigating to the entity's instance page and using the Add button within the Associated Properties at this Level section.

There are two options when adding the properties:

• create a new property definition and associate it to the entity by selecting Create new property

• choose one or many existing properties and associate them to the entity by selecting Associate existing property

Regarding already existing properties, a list of all (or all unused) properties that have been created in all Domain Namespaces or Integration Namespaces of the project are shown. It is also possible to search for a specific property using the Search capability. One or more property definitions can be selected in order to be added to the entity.

While associating a property you can overwrite or adjust the pre-filled name of the association.