Patching

An application that has been installed using the Microsoft Windows Installer can be upgraded by reinstalling an updated installation package (.msi file), or by applying a Windows Installer patch (an .msp file) to the application.

A Windows Installer patch (.msp file) is a self-contained package that contains the updates to the application and describes which versions of the application can receive the patch. Patches contain at a minimum, two database transforms and can contain patch files that are stored in the cabinet file stream of the patch package. For more information about the parts of a Windows Installer patch package, see Patch Packages.

Servicing applications by delivering a Windows Installer patch, rather than a complete installation package for the updated product can have advantages. A patch can contain an entire file or only the file bits necessary to update part of the file. This can enable the user to download an upgrade patch that is much smaller than the installation package for the entire product. An update using a patch can preserve a user customization of the application through the upgrade.

**Windows Installer 4.5 and later:В В **

Beginning with Windows Installer 4.5, developers can mark components in a patch with the msidbComponentAttributesUninstallOnSupersedence value in the Component table. If a subsequent patch is installed, marked with the msidbPatchSequenceSupersedeEarlier value in its MsiPatchSequence table to supersede the first patch, Windows Installer 4.5 and later can unregister and uninstall components marked msidbComponentAttributesUninstallOnSupersedence to prevent leaving behind unused components on the computer. If the component is not marked with with this bit, installation of the superseding patch can leave an unused component on the computer. Setting the MSIUNINSTALLSUPERSEDEDCOMPONENTS property has the same effect as setting this bit for all components.

**Windows Installer 3.0 and later:В В **

Developers who use Windows Installer 3.0, and author patch packages that have the MsiPatchSequence table can create patch packages that do the following:

• Use the product baseline cached by the installer to more easily service applications with smaller delta patches. For more information about using the product baseline, see Reducing Patch Size.
• Skip actions associated with specific tables that are unmodified by the patch. This can significantly reduce the time required to install the patch. For more information about which tables can be skipped, see Patch Optimization.
• Create and install patches that can be uninstalled singly, and in any order, without having to uninstall and reinstall the entire application and other patches. For more information about uninstalling patches, see Removing Patches.
• Apply patches in a constant order regardless of the order that the patches are provided to the system. For more information about how the Windows Installer determines the sequence used to apply patches, see Sequencing Patches.
• Apply patches to an application that has been installed in a per-user-managed context. For more information, see Patching Per-User Managed Applications.

**Windows Installer 2.0:В В **

The MsiPatchSequence table is not supported. Beginning with Windows Installer 3.0, patch packages can contain information that describes the patching sequence for the patch relative to other updates and additional descriptive information.

The recommended method for creating a patch package is to use patch creation tools such as Msimsp.exe and Patchwiz.dll. Developers can generate a patch creation file as described in the section: Creating a Patch Package. The creation of a small update patch is described in the section: A Small Update Patching Example.

Microsoft Windows Installer accepts a Uniform Resource Locator (URL) as a valid source for a patch. For more information about how to install a patch located on a Web server, see Downloading and Installing a Patch From the Internet.

A single Windows Installer patch (.msp file) can be applied to the installation package when installing an application for the first time. For more information, see Patching Initial Installations.

It is not possible to eliminate all circumstances when the application of a patch may require access to the original installation source. However, to minimize the possibility that your patch will require access to the original source, adhere to the points listed in the following section: Preventing a Patch from Requiring Access to the Original Installation Source.

To minimize the possibility that your patch is not broken by a subsequent customization transform, typically the patch is installed first, followed by the customization. Installing customization transforms first, and then the patch, may break the customization. For more information about patching customized applications, see Patching Customized Applications.

Microsoft Windows Best Practices and Patch Guides

Updates for systems with Windows operating system and its products are called Service Packs, patches and security patches. These updates provide a fairly quick and prescribed solution or workaround for a problem. However, these updates should only be performed when needed, regardless of their nature, that is, only if they are capable of resolving a problem that bothers a customer. The update must also be evaluated before installation. In short, it is not absolutely necessary to install updates immediately.

Best practices for Windows patches

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Security patches minimize security risks and other vulnerabilities. These patches are similar to the patches. Microsoft mainly offers several ways to get security patches for its products. These are the ones:

1. Windows Update : Uses ActiveX technology to check the latest security protection and the best drivers and software installed on a PC. Once completed, displays a list of proposed components that require updating.
2. Current safety bulletins : Everything from one source to find relevant security patches. It allows you to search by product or date.
3. Product-specific download pages for security patches : Provides security patches for specific products. For example Internet Explorer (IE) and Office Updates. The security patches on the IE download page differ from Windows Update in that the IE download page does not allow you to identify patches already installed such as Windows Update.
4. Microsoft Download Center (MDC) : Search by product name, product category or operating system.
5. Email Notification Subscription: Notifies a user of the latest proactive email security fixes. Security patches must be installed to comply with these best practices.

Otherwise, Windows 8 and Windows Server 2012 use a different patch method than previous versions.

The three types of updates for these operating systems include

1. Global Standalone Patch: The patch is designed to cover critical operating system issues and is usually released in different languages. It is thoroughly tested before being published.
2. Limited update: Contains patches that are generated following a critical customer support incident and must therefore be made available within a specified time.
3. Monthly Rollup: strives to maintain the Windows 8/2012 operating system family each month through monthly rollups.

Patch Guide for Windows 8.1 and Windows Server 2012 R2

1] Install all available rollups since the last milestone, i.e. from Windows 8 to Windows 8.1 or from Windows Server 2012 to Windows Server 2012 R2

2] Use Windows Update or Windows Server Update Services. You evaluate which patches are currently installed, what patches are available, check which patches are replaced, and provide a list of currently available patches.

3] Critical updates should be tested and installed as quickly as possible with high priority.

4] Important updates should be tested and installed as soon as possible.

5] Recommended and optional updates can be reviewed, tested and installed as required.

When should Windows security patches

1. Request exact match only: Apply the security patch only if you are sure that the update solves the problem you encountered.
2. Apply admin patches to install build areas: The post mentions that admin patches are different from client patches and are generally located at a different location from client-side patches.

Therefore, it is important that not only customers are then updated with security patches, but also the areas created by the customer for new customers. Most security updates published are for client-side issues (often browsers). They can be complete or remotely relevant for a server installation. You should try to get both the admin patch and the client patch, as the client patch retroactively updates the client database and the admin patch probably updates your client’s build area on the server.

Microsoft’s blog lists best practices for deploying Microsoft service packs and security patches and provides useful links. You will find more information in this article on TechNet.

Patching and Upgrades

Because an installation package can contain the files that make up an application as well the information needed for their installation, Windows Installer can be used to update the application. The installer can update information in the following parts of the installation package:

• The .msi file.
• The files of the application.
• The Windows Installer registration information.

The type of update can be characterized by the changes the update makes to the application’s product code, product version, and package code. The application’s product version is stored in the ProductVersion property. The application’s product code is stored in the ProductCode property. The application’s package code is stored in the Revision Number Summary Property.

An update that changes the application into another product is required to change the ProductCode of the application. For more information about which updates require changing the ProductCode see Changing the Product Code. The update can change the ProductVersion and leave the ProductCode unchanged if future versions of the application will need to differentiate between the updated and nonupdated versions of the current product. The Package Code uniquely identifies the installation package and should always be changed whenever update or upgrade changes any information in the installation package.

When deciding whether to change the product version, you should consider If future versions of the application will need to differentiate between the updated and nonupdated versions of the current product. To ensure differentiation in the future, a minor upgrade should be used instead of a small update.

• If an update changes the .msi file and application files, but does not change the ProductCode property or ProductVersion property, it is termed a small update.
• If the update changes the ProductVersion, but does not change the ProductCode, it is termed a minor upgrade.
• If the update changes the installation into an entirely different product, the ProductCode must change and the update is termed a major upgrade.

To ensure differentiation of versions of the current product in the future, a minor upgrade should be used instead of a small update.

The following table summarizes the different types of updates.

Type of update	Productcode	ProductVersion	Description
Small Update	No change	No change	An update to one or two files that is too small to warrant changing the ProductVersion. The package code in the Revision Number Summary Property does change. Can be shipped as a full installation package or as a patch package.
Minor Upgrade	No change	Changed	A small update making changes significant enough to warrant changing the ProductVersion property. Can be shipped as a full installation package or as a patch package.
Major Upgrades	Changed	Changed	A comprehensive update of the product warranting a change in the ProductCode property. Shipped as a patch package or as a full product installation package.

The Windows Installer can install an application, or an update, for all users of a computer (per-machine context) or for a particular user (per-user context) depending on the access privileges of the user, the value of the ALLUSERS property, and the version of the operating system. Application developers should consider in which context updates will be installed. If the contexts of the application and update are different, the application may not be updated as expected.

Users can update to an application by reinstalling a Windows Installer package for the application. Note that Minor Upgrades can be applied in the same way as Small Updates. For more information about updating an application by reinstalling the application, see these sections:

An update to an application can be provided to users as a Windows Installer patch package. A patch can contain an entire file or only the file bits necessary to update part of a file. This means that the user can download an upgrade patch that is much smaller than the entire product and that preserves user customizations through the upgrade. Note that Minor Upgrades can be applied in the same way as Small Updates. For more information about updating an application using a patch, see these sections: