Helper Apps

Standard File Types

This page provides links to a number of file types. Many of these file types will display directly inside a browser window but some will not. Those file types that cannot be displayed directly will require an external program, sometimes known as "helper apps". You can use this page to test your browser to determine if it has been properly configured to display the data types you plan to use in your physics lessons.

The following data types will display directly in most browsers:

• ASCII Text file.
• Directory listing.
• GIF picture
• JPG picture

The following data types usually require helper apps.

• Quick Time movie.
• AVI movie.
• MPG movie file.
• Sound in Sun audio format.
• Sound in WAV audio format.
• Windows HELP file.
• MS Word document file.
• Mathematica notebook file.

As you can see, helper applications are very general and allow you to incorporate almost any file type, including propritiery file types such as Mathematica or Microsoft Word files, into a lesson plan. Although the current generation of helper apps are standalone applications, the next generation of these applications, called plug-ins, will be able to display data directly within the browser window.

LAUNCH a Program

Strangely enough, it is not easy to download and run standard DOS or Windows executable programs, i.e., a EXE or BAT files, from within a browser. This is probably due to the philosophy behind the web. HTML should be platform independent. Nevertheless, it is sometimes useful to break the rules. The following MS Windows helper app, LAUNCH, can handle *.EXE and *.BAT files. These file types will download into the temporary directory, usually C:\TEMP, just like JPG or GIF files. They then execute.

• Notepad using a path in Windows.
• Notepad via *.bat file.

You may have noticed that BAT files started by LAUNCH leave an open DOS window on the screen after they finish execution. In addition, BAT files do not use some of the networking and multi-threading features of Windows 95. LAUCH recognizes one additional file type, LHR, that is designed to overcome these problems. LHR files are text files that list the application name followed by the data file, i.e.,
c:\apps\mathematica.exe wave.ma.
Notice the Mathematica.EXE is not copied over the network. Only the very small text file is copied to tell LAUNCH where to find Mathematica and what file it should load. Multiple applications can be started in a single LHR file and each application will start independently in its own thread. A DOS window will not open as in the case of BAT files.

• Video Point via *.lhr file.

Why use LAUNCH rather than associate helper apps with a file type such as *.MOV for quick time movies? Suppose you want students to use a video analysis tool such as VideoPoint to analyze the movie. Writing the following text file

seems better than having every student change their Netscape preferences!

Launch was written by Wolfgang Christian