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Virtualizing desktops can cause application compatibility issues, but Citrix's AppDNA tool lets you find and fix problems.
One of the biggest considerations that organizations looking at virtualizing desktops have to face is whether applications will function correctly in the new environment. Conventional wisdom dictates performing rigorous manual application testing, but granular application testing isn't practical. Your organization may have so many applications that it is nearly impossible to test them all. Even if you have a manageable number of apps, it is unrealistic to test every feature of every application.
This is where Citrix AppDNA comes in. AppDNA is not specifically geared toward virtual desktop migrations, but you can use it to make the transition easier. It is a tool for anticipating application compatibility issues in various operating systems.
AppDNA versus Application Compatibility Manager
There are several tools available to help you compile an application inventory and verify compatibility with various operating systems. The Microsoft Application Compatibility Manager is a free utility designed to do just that, but there are major differences between the way it and AppDNA work.
The Microsoft Application Compatibility Manager compiles an inventory of applications that run on users' desktops, and it enters that information into a database. The tool then displays the application vendor's assessment and the IT community's assessment of the application's ability to function within a given operating system. It even provides information about known issues and workarounds.
The Microsoft Application Compatibility Manager works well and is often a go-to resource for those considering an operating system migration. AppDNA uses a completely different approach to accomplish the same goal, and it can potentially give you better results.
AppDNA works by examining the application's installer file to learn about it, rather than simply displaying compatibility information that other people have provided (as is the case for the Microsoft tool).
Many Windows applications use MSI-based installers. An MSI file contains a table listing all of the files and registry entries that will be written to the system when the application is installed. If an application has an MSI-based installer, AppDNA will examine the actions that the installer takes. If an application uses some other type of installer, AppDNA will launch a virtual machine, install the application and use diffing to build a custom MSI that it can analyze.
In addition to analyzing an application's installer, AppDNA also analyzes the application's files -- usually without installing the application -- to learn about its dependencies. This goes a long way toward enabling you to evaluate an application's compatibility.
AppDNA focuses heavily on applications, but it also looks at the operating system. You can bring one or more reference images into AppDNA to gauge how installing an application will affect that particular operating system and configuration. As such, you can experiment with various "what-if" situations without actually having to install the applications.
AppDNA for remediation
In addition to being a testing and reporting tool, AppDNA can also perform application remediation when necessary. For each application, AppDNA reports whether any remediation is required. In some cases, AppDNA provides a link that you can use to perform an automatic fix for an application. In other cases, Microsoft provides shims that you can apply through AppDNA.
When app remediation cannot happen automatically, there may be manual processes you have to perform to get an application to run properly on a new OS. In these types of situations, AppDNA provides detailed information about what you need to do to make the application run. There is also a built-in effort calculator that you can use to estimate the number of man-hours and dollars you'll have to put into performing the remediation.
The effort calculator also breaks down the cost and time commitment involved in performing the remediation with and without AppDNA, so you can get a feel for the return on investment. These calculations include the cost of the AppDNA licenses.
AppDNA is probably best suited for large organizations that need to quickly evaluate and remediate large numbers of applications. Smaller organizations could likely get by using one of the many free tools that are on the market in combination with manual compatibility testing.