Tarma WebUpdate

Outline of operation | Where to find Tarma WebUpdate | System requirements | Reference

Tarma WebUpdate (TWU) is a dynamic link library (DLL) that enables you to perform automatic software updates from your applications. It offers the following functionality:

Local and remote package retrieval

Routines that retrieve package information either locally or remotely (using FTP, HTTP, or HTTPS) and download the corresponding installers to a local file.

Update version checking

Routines that retrieve information about locally installed packages and compare them with the remote package information to determine if an update is required.

Installer execution

Routines that run the downloaded installers in order to update an application.

Outline of operation

To use the Tarma WebUpdate functionality in your own application, you must add some application-specific code that uses the Tarma WebUpdate (TWU) routines. In addition, you must provide the following:

• A package information file that describes the remote packages. This is a small text file that must be placed on an Internet server (FTP, HTTP, or HTTPS). You can also place this file on a local server or even on the local system; in that case, you must specify the file: protocol when you retrieve the file with TWUOpenUpdateURL.
• The actual installation packages. These must be placed on the same server as the package information file. There are no special requirements for these installation packages; they can be the same packages that you would distribute otherwise. Furthermore, they do not have to be Tarma Installer packages; any executable or MSI-based installer can be used.

During a typical Tarma WebUpdate session, the following actions take place:

1. Your application contacts your Internet server and retrieves the package information file for your application. This is done with the TWUOpenUpdateURL function.
2. The package information is enumerated and compared to the currently installed version of the application. This is done with a combination of the TWUEnumPackages, TWUFindInstalledInfo, TWUCheckUpdateVersion, and TWUCompareVersions functions.
3. For each package that must be installed, its installer is retrieved from the server by the TWUGetPackageInstaller function and executed by the TWURunPackageInstaller function.
4. Any (temporary) downloaded files are removed with TWUCleanupDownloads and the connection is closed with TWUCloseSession.

The Tarma WebUpdate sample application demonstrates how to use the Tarma WebUpdate functionality.

Where to find Tarma WebUpdate

The Tarma WebUpdate components are installed along with the rest of Tarma ExpertInstall. The following files are used with Tarma WebUpdate (all files and folders are relative to the Tarma ExpertInstall installation folder, typically C:\Program Files\Tarma ExpertInstall):

System requirements

Tarma WebUpdate has the following system requirements:

• Windows 95, 98, Me, NT4, 2000, XP, 2003.
• WinInet.dll - This is a Windows system component that is available on all 32-bit Windows version that have Internet Explorer 3.0 or later installed.
• A network connection for access to remote packages and package information. The usual TCP/IP ports are used for the various protocols (FTP: port 22, HTTP: port 80, HTTPS: port 443), so any firewalls must allow traffic through these ports.

To build an application that uses Tarma WebUpdate, you will need the a Microsoft Visual C++ compiler (6.0, 7.0, 7.1) and the files mentioned above. You can use either the ANSI or the Unicode versions of the TWU entry points.

Reference

Refer to the following topics for more information about the various functions and types.