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view them independently of each other. However, using the OVA (single i le) format does make
it easier to move the OVF template between locations because you work with only a single i le.
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h e full OVF specifi cation as approved by the Desktop Management Task Force (DMTF) is available
from the DMTF website at
www.dmtf.org/standards/ovf.
At the time this topic was written,
the latest version of the specifi cation was version 1.1.0, published in January 2010.
The OVF specii cation also gives OVF templates another interesting ability: the abil-
ity to encapsulate multiple VMs inside a single OVF template. The OVF descriptor con-
tains elements that specify whether the OVF template contains a single VM (noted by the
VirtualSystem element, which you can see in Listing 10.1) or multiple VMs (noted by the
VirtualSystemCollection element). An OVF template that contains multiple VMs would allow
a vSphere administrator to deploy an entire collection of VMs from a single OVF template.
In fact, vSphere leverages this ability of an OVF template to encapsulate multiple VMs in a
key feature known as vApps.
Working with vApps
vApps are a way for vSphere administrators to combine multiple VMs into a single unit. Why
is this functionality useful? Increasingly, enterprise applications are no longer constrained to
a single VM. Instead, they may have components spread across multiple VMs. For example, a
typical multitier application might have one or more frontend web servers, an application server,
and a backend database server. Although each of these servers is a discrete VM and could be
managed as such, they are also part of a larger application that is servicing the organization.
Combining these different VMs into a vApp allows the vSphere administrator to manage the
different VMs as a single unit.
In the following sections, we'll show you how to work with vApps, including creating vApps
and editing vApps. Let's start with creating a vApp.
Creating a vApp
Creating a vApp is a two-step process. First, you create the vApp container and coni gure any
settings. Second, you add one or more VMs to the vApp, by cloning existing VMs, deploying
from a template, or creating a new VM from scratch in the vApp. You repeat the process of add-
ing VMs until you have all the necessary VMs contained in the vApp.
Perform these steps to create a vApp:
1.
If it is not already running, launch the vSphere Web Client and connect to a vCenter
Server instance or launch the traditional vSphere Client and connect to a stand-alone
ESXi host.
