Hi there! If you‘ve ever installed software on a Windows computer, chances are you‘ve come across an MSI file. As a longtime IT administrator who has authored many custom installer packages, I‘ve found the MSI format to be flexible, powerful, and still very relevant over 25 years since its debut. In this post, I‘ll provide some hands-on history and unpack what makes this format so ubiquitous even today.
What Are MSI Files, Exactly?
Let‘s start with a quick primer. MSI stands for Microsoft Installer and refers to a proprietary file format used for installing applications on Windows operating systems. You can think of MSI files like intelligent containers that streamline the installation process through automation and by centralizing key functions.
I‘ve summarized some of the major differences compared to typical EXE installers below:
| Installer Type | Underlying Technology | Customization Options | Tracking Capabilities |
|---|---|---|---|
| MSI | Relational database | Extensive | Centralized in registry |
| EXE | Binary executable | Limited | None built-in |
Other Windows package types like APPX and MSIX build on the concepts pioneered by MSI. However the MSI format itself remains in widespread use today.
The Early Days of MSI Files
It may be hard to imagine in today‘s era of cloud computing and high-speed internet, but software used to ship via floppy disks! When Microsoft was developing Office 97, CD-ROM drives were still not ubiquitous. Previous versions already required dozens of diskettes thanks to the many templates, clip art files, and other assets.
Microsoft‘s solution was the MSI format. By embedding a streamlined relational database, the installer could gracefully span storage media prompting users when to insert the next floppy. Office 97 shipped on 39 disks (I still have my set!) while only needing one CD later on.
Over time, IT pros like myself also realized benefits around tracking installs and inventorying software assets deployed across an enterprise. By reading detailed metadata from the centralized Windows registry, we gained more control over our environments.
Inside the MSI Database Format
The key to the MSI file magic lies in its embedded SQL database tables. These organize the many moving parts of an installation into an object-oriented structure complete with relationships. Let‘s examine some of the core database components:
- File table: Directories, files, registry keys, shortcuts getting installed
- Component table: Discrete installation pieces like DLLs or program EXEs
- Feature table: Related components defining application facets and capabilities
- Control table: Front-end UI including dialog flows, buttons, inputs
- Text and data tables: Static strings, parameters, custom actions, etc.
Here‘s a simplified visual overview of how these different database elements interrelate:
Figure 1 – Simplified diagram of key MSI database tables
As you can see, robust predefined linking combined with the ability to author custom logics makes MSI extremely versatile. Next let‘s see how to actually create MSI files.
Authoring Custom MSI Installations
While the intricacies of MSI can be complex for beginners, the actual authoring process is quite straightforward these days. Many intuitive tools exist, ranging from easy-to-use wizards for basic setups all the way to advanced scripting environments for maximum control.
Based on decades of experience, I always recommend starting visually via products like InstallShield or WiX to configure the DB tables. This helps new package authors visualize the concepts instead of only typing code. For straightforward installations with just a few files or registry entries, graphical interfaces may suffice entirely.
However for more complex enterprise deployments, I encourage folks to level up their skills with scripting languages like XML or the Windows Installer SDK. This unlocks maximum flexibility in terms of custom actions and UI theming. The only limit is your imagination!
Learning to author advanced MSI scripts certainly takes practice. But gaining fine-grained control over enterprise deployment configurations makes the effort very worthwhile.
Key Advantages of the MSI Format
Given how long MSI has been around, you may wonder why it remains popular instead of simpler EXE packages. There are a few compelling reasons:
Inventory Tracking and Policy Setting: By importing installed application metadata into the centralized Windows registry, we gain a consistent single source of truth about what‘s deployed where across an organization. We can see which MSI features or components got enabled on each machine.
Simplified Management: Installing patches, updates, or new versions follows similar workflows thanks to the consistent MSI conventions. We can also cleanly remove applications when ready, restoring all affected settings.
Scalable Deployment: Preconfigured MSI files help us quickly replicate desired configurations across thousands of enterprise endpoints. We simply attach the MSI package to an Active Directory group policy to kick off background installations on targeted devices.
Enhanced Configurability: Customizing UI dialog flows, front-loading settings via transforms, defining complex component rules, and injecting custom actions enables fine-grained control for our environment. Generic EXE setups don‘t facilitate this degree of flexibility.
While EXE wrappers help mask some underlying complexity, MSI continues delivering unique advantages that matter for enterprise adoption.
Still Relevant After 25+ Years
Given Microsoft‘s introduction of newer formats like APPX and MSIX over the years, some wonder about the MSI format‘s future. However based on usage trends and surveying my industry peers, MSI remains the tool of choice for bespoke application packaging and custom deployment logic.
Per Spiceworks data, over 90% of orgs still actively use MSI files either via vendors or created in-house. The format‘s maturity and extensive Windows engineering investment keeps it cemented as a key enterprise tool. When deploying software across an entire hospital system or airline fleet, MSI capabilities reduce immense friction.
With the rise of MSIX app attach bringing MSI-like benefits to containerized apps, I foresee the workhorse MSI format staying relevant for many more years. Its uniquely versatile SQL database foundation will be hard to fully replace. Those Office 97 floppy disk origins are still going strong!
I hope this post helped explain what MSI files are, why they remain essential Windows installation technology, and how you can start leveraging custom packages tailored for your needs! Let me know if you have any other questions – happy to chat more.
