7.3

Table 1‑5. Workflow Subscription and Event Broker Terminology (Continued)
Term Description
System Workow Subscription A specialized workow subscription that reacts to system
events and to events in all the tenants.
Tenant Workow Subscription A specialized workow subscription that species which
conditions trigger a vRealize Orchestrator workow for
events in the same tenant.
Blockable and Replyable Event Topics
Event topics might support blockable and replyable events. The behavior of a workow subscription
depends on whether the topic supports these event types and how you congure the workow subscription.
Non-Blockable Event Topics
Non-blockable event topics only allow you to create non-blocking subscriptions. Non-blocking subscriptions
are triggered asynchronously and you can not rely on the order that the subscriptions are triggered or that
the vRealize Orchestrator workows run. Non-blocking subscriptions only return a response if the topic is
replyable.
Blockable Event Topics
Some event topics support blocking. If a workow subscription is marked as blocking, then all messages
that meet the congured conditions are not received by any other workow subscriptions with matching
conditions until the rst workow is nished. If you have multiple blocking workow subscriptions for the
same event topic, you prioritize the subscriptions.
Blocking subscriptions run in priority order. The highest priority value is 0 (zero). If you have more than one
blocking subscription for the same event topic with the same priority level, the subscriptions run in
alphabetical order based on the name. After all blocking subscriptions are processed, the message is sent to
all the nonblocking subscriptions at the same time. Because the blocking workow subscriptions run
synchronously, the changed event payload includes the updated event when the subsequent workow
subscriptions are notied.
You apply blocking to one or more workow subscriptions depending on the selected workow and your
goals.
For example, you have two provisioning workow subscriptions where the second workow depends on
the results of the rst. The rst one changes a property during provisioning, and a second records the new
property, perhaps a machine name, in a le system. The ChangeProperty subscription is prioritized as 0 and
the RecordProperty is prioritized as 1 because it uses the results of the ChangeProperty subscription. When
a machine is provisioned, the ChangeProperty subscription begins running. Because the RecordProperty
subscription conditions are based on a post-provisioning conditions, a message triggers the RecordProperty
subscription. However, because the ChangeProperty workow is a blocking workow, the message is not
received until it is nished. When the name is changed and the rst workow is nished, the second
workow runs, recording the name in the le system.
Even if an event topics that support blocking, you can create a non-blocking workow subscription if the
workow subscription does not have any dependant subsequent workows. The workow subscription is
triggered and runs the vRealize Orchestrator workow without further interaction from
vRealize Automation or the outside system.
Chapter 1 Life Cycle Extensibility
VMware, Inc. 15