Installing HTAs

As mentioned before, there are two basic models by which you can deploy HTAs, run-based and copy-based. Let's summarize their pluses and minuses.

Copy-based. This is the traditional model for installing Windows applications. Files are copied from the disk or over the network, using any installation or self-extracting utilities. Both Internet Explorer and Netscape Navigator include such utilities and are able to install HTAs. The installer positions the application in the Program File directory, unless the user selects a different directory. It also puts a link to the HTA in the Start menu. The dependency of the application on Internet Explorer 5.0 or greater is registered, and the user is warned before attempting to uninstall the browser. Vendors are busily working now on new tools for packaging and releasing HTAs.

There are several advantages to the copy-based model. The user is prompted only once during the initial installation, and runs it later as an ordinary executable. The main advantage is that you don't have to be connected to the server to run the application. This is especially important when you are on the road and don't have a communication link on your laptop. You'd better install your applications beforehand.

Browser-based. In this model the HTA is invoked just like a Web page. The HTA is launched just by clicking on its URL, or accessing it via the Internet Explorer Favorites. Before the HTA is launched, the user is asked whether to open or save it. After opening the HTA, all needed files are loaded from the server into the client's cache. Servers need to have the MIME type "application:hta" registered.

There are several advantages to the browser-based model. Updates to the application are immediate and transparent to the user. The application just changes on the fly and users even don't know they are running a newer version than the one they ran yesterday. It is very easy for users. They need never install or uninstall applications. The main drawback is that applications are not accessible when the server goes down or when the user is not connected to the server.