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What Good is a GUID?

Windows installer makes heavy use of these almost unreadable alphanumeric strings in curly braces, also known as "GUID", like this:


GUID is the abbreviation for Globally Unique Identifier. It is a 128-bit number, represented as a string of hexadecimal digits. There is an operating system function that can create such unique numbers. To a "very high degree of certainty" (as Microsoft puts it), this function returns a unique value and your development machine should be equipped with a network card to avoid another computer generating an identical GUID.

GUIDs are nothing new. For instance they are used to identify classes, objects and interfaces in ActiveX applications. However Windows Installer has introduced a new requirement for GUIDs. While tools like Visual Studio often use lower case letters to represent hex digits, GUIDs used in Windows Installer must be in all upper case characters. If you use the "Generate GUID" buttons that InstallShield has placed in all relevant locations of the IPWI development environment, you don't have to worry about this.

A Tips and Tricks article, About Component, Package, Product, and Upgrade Codes in Windows Installer, describes the locations where GUIDs are used and the importance of unique identifiers across a development team.

Download the article today to make sure your GUIDs are good!  What ways have you avoided duplicate GUIDs?


InstallShield® is the world's leading Windows installation development solution. InstallShield is designed to enable development teams to be more agile, collaborative and flexible when building reliable InstallScript and Windows Installer MSI installations for desktop, server, Web, virtual and traditional applications. The software installer of choice for today's sophisticated application producers, InstallShield is the only software installer that can directly convert MSIs to Microsoft App-V virtual packages. Get your free trial of InstallShield today or contact us for more information.

InstallAnywhere is the leading multiplatform development solution for application producers who need to deliver a professional and consistent cross installation experience for physical, virtual and cloud environments. From a single project file and build environment, InstallAnywhere creates reliable installations for on-premises platforms – Windows, Linux, Apple OS X, Solaris, AIX , HP-UX, and IBM iSeries – and enables you to take existing and new software products to a virtual and cloud infrastructure.  Get your free trial of InstallAnywhere or contact us for more information.

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