6.2

IaaS Website
The IaaS Website component, also called the Model Manager Web, provides the infrastructure
administration and service authoring capabilities to the vRealize Automation console. The Website
component communicates with the Model Manager, which provides it with updates from the Distributed
Execution Manager (DEM), proxy agents, and database.
Model Manager
vRealize Automation models facilitate integration with external systems and databases. They implement
business logic that a Distributed Execution Manager (DEM) uses.
The Model Manager provides services and utilities for persisting, versioning, securing, and distributing
model elements. It communicates with the database, the DEMs, and the console Web site.
vCloud Automation Center Manager Service
The Manager Service coordinates communication between DEMS, agents, and the database. The
Manager Service communicates with the console Web site through the Model Manager. This service
requires administrative privileges to run.
IaaS Database
The IaaS component of vRealize Automation uses a Microsoft SQL Server database to maintain
information about the machines it manages and its own elements and policies. Typically, a system
administrator creates the database during installation.
Distributed Execution Managers
A Distributed Execution Manager (DEM) runs the business logic of custom models, interacting with the
database and with external databases and systems as required.
Each DEM instance acts in either a Worker role or in an Orchestrator role. The Worker role is responsible
for running workflows. The Orchestrator role is responsible for monitoring DEM Worker instances,
preprocessing workflows to run, and scheduling workflows.
The DEM Orchestrator performs these specific tasks.
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Monitors the status of DEM Workers and ensures that if a Worker instance stops or loses its
connection to the Model Manager, its workflows are put back in the queue for another DEM Worker to
pick up.
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Manages scheduled workflows by creating new workflow instances at the scheduled time.
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Ensures that only one instance of a particular scheduled workflow is running at a given time.
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Preprocesses workflows before they are run, including checking preconditions for workflows, used in
the implementation of the RunOneOnly feature, and creating the workflow execution history.
Installation and Configuration
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