Internet Packages

See Also

Internet packages are .cab-based setup programs that are designed to be downloaded from a Web site. Internet Explorer uses a process known as Internet Component Download to install your Internet application. The Package and Deployment Wizard automatically includes information needed for this process in the packages it creates.

There are several types of Visual Basic applications or components that can be packaged for Internet deployment, including:

For More Information   Extensive information about the Internet Component Download process can be found in "Downloading ActiveX Components" in Building Internet Applications in the Component Tools Guide.

Parts of an Internet Package

There are several files that are always part of your Internet packages. These include:

Secondary .cab files provide an efficient way to ensure that the user has the most current version of components. If a newer version of a component in a secondary .cab file becomes available on the external Web site, users who download your application will receive the updated version automatically.

Note   If you cannot or do not want your application setup to require a connection to the Internet, you may place the secondary .cab files on a server within your intranet. An intranet server often provides for faster downloading and allows users to download from a secure network.

How Internet Component Download Works

After you package your Internet application or component for download, you deploy it to a specific location on a Web server, from which users can access it. Usually, your package is referenced as part of an existing Web page — that is, your control or other component is hosted by a Web page.

When a user accesses the Web page that hosts your package, the system downloads your package to the user's computer. The package is verified for safety, unpacked, registered, installed, and then activated. All of this occurs in the background and is controlled by the browser.

The Package and Deployment Wizard plays two parts in the process described above:

  1. It packages your component and its associated files into a compressed (.cab) file that the browser uses to download your component. The Package and Deployment Wizard determines which files your project needs to run, gathers those files, compresses them into a .cab file, and generates the HTML that points to your component.

  2. It deploys your packaged files to the Web server location of your choice. For more information on deploying your Internet component download package, see "Application Deployment with the Wizard" later in this chapter.

Safety Issues

When you prepare Internet applications and components for download, you must package them into a file that can be delivered to the user through a browser. In addition, you must perform a few precautionary steps to ensure users that your application will not harm their computers. These steps can include:

Safety settings can be made within the Package and Deployment Wizard. When you work with an Internet package, a screen in the wizard asks you to verify safety settings. This screen appears lists only the objects in your project that do not implement a safety interface called IObjectSafety.

Note   Signing and licensing must be done outside of the packaging process. You should arrange licensing for any components before you package the component. Digital signing can be done after you package the application — the Package and Deployment Wizard reserves space within the .cab file for information about the digital signature.

For More Information   See "Steps to Prepare your Component for Download" in the Building Internet Applications book of the Component Tools Guide for detailed explanations of component safety, licensing, and signing. See "Setting Safety Levels for ActiveX Components" in "Downloading ActiveX Components" in Building Internet Applications in the Component Tools Guide for more information on the IObjectSafety interface.