You must create a custom resource so that you can create an advanced service for provisioning with the option to access and manage the provisioned items. Custom resources define the items for provisioning, and you can use them to define post-provisioning operations that the consumers can perform.
You create a custom resource to define a new type of provisioned item and map it to an existing vRealize Orchestrator object type. vRealize Orchestrator object types are the objects exposed through the APIs of the vRealize Orchestrator plug-ins. The custom resource is the output type of a blueprint workflow for provisioning and can be the input type for a resource action workflow.
For example, if you have a running vCenter Server instance, and you also have the vCenter Server plug-in that is configured to work with vRealize Orchestrator, all of the object types from the vCenter Server API are exposed in vRealize Orchestrator. The vCenter Server plug-in exposes the vSphere inventory objects in the vRealize Orchestrator inventory. The vSphere inventory objects include data centers, folders, ESXi hosts, virtual machines and appliances, resource pools, and so on. You can perform operations on these objects. For example, you can create, clone, or destroy virtual machines.
For more information about the vRealize Orchestrator object types exposed through the vCenter Server API, see the vCenter Server 5.5 Plug-In API Reference for vCenter Orchestrator.