VAPs are virtual machine (VM) templates, sometimes in the Open Virtualization Format (OVF), that contain preconfigured operating systems and applications.
Because VMs are self-contained and transportable, they can be delivered in a preconfigured state as VAPs.
The appliances are most often designed to run on Linux operating systems because of the licensing costs associated with software deployment. Few third-party vendors have created VAPs based on Microsoft technologies because they have to become Windows resellers to do so. Microsoft has produced a number of VAPs for evaluation purposes. But because it is possible to add a license to both the OS and the application within it, a Microsoft evaluation VAP works just as well as any other VAP.
How virtual appliances benefit software deployment
Virtual appliances further decrease software deployment time, because the applications they contain are preconfigured and ready to run. Given this, you may never need to install another product again; just get it in a VAP, integrate it into your network and run it.
Physical IT appliances have been around for quite some time. Several different types of appliances are available: network intrusion detection systems, search engines, firewalls, storage servers, configuration management servers, network load balancing servers and more.
Each of these devices is really easy to deploy and use -- mount it in a rack, give it an IP address and then log into it to configure it. Configuration is usually performed in a Web interface through a browser. Use the IP address you assigned the device to go to the configuration page, change or assign an administrative password and move on to the configuration of the features included in the device.
VAPs are even easier to set up than physical appliances. Copy the files that make up the VAP into a file folder on a server or import them if they are in OVF form, and then launch the VM that makes up the appliance to finalize the configuration. But, even if they are easy to set up and install, you still need to prepare your VAPs carefully.
Potential pitfalls with virtual appliances
In the physical world, your main concern is if the appliance will fit into your racks. But in the virtual world, you must ensure that the virtual appliances you obtain rely on the virtualization technology you have decided to deploy in your network. For example, if you chose to standardize with VMware as your virtualization provider and the VAP you select comes in another format, you'll most likely either have to convert it to a VMware format or choose not to obtain it. After all, you don't want to run multiple virtualization engines if you can help it.
Make sure that the conversion process does not void any warranties provided by the manufacturer because conversion can change the nature of the VM. It's always good to check with the manufacturer that the VAP will run on your virtual infrastructure.
In every case, using VAPs vastly reduces software deployment time and simplifies the use of complex server applications. You can also create your own VAPs if the applications you need are not available commercially.
Creating your own VAP is like creating a seed machine for new VMs, except that in addition to installing the OS and configuring it for use, you also install the application before you generalize the VM. That way, you speed up the deployment process of any server application in your network.
VAPs are here to stay. Using them for software deployment has never been easier, whether you use commercial VAPs or create your own.
About the authors
Danielle Ruest and Nelson Ruest are IT experts focused on continuous service availability and infrastructure optimization. They are authors of multiple books, including Virtualization: A Beginner's Guide and the Windows Server 2008, The Complete Reference for McGraw Hill Osborne as well as the MCITP Self-Paced Training Kit (Exam 70-238): Deploying Messaging Solutions with Microsoft Exchange Server 2007 for MS Press. Their newest work is a training kit for Microsoft exam 70-652: Configuring Windows Server Virtualization with Hyper-V. Contact them at email@example.com.