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Configuring Helper Applications

Mosaic can read HTML documents, GIF and JPEG graphics, and AU and AIFF audio file formats. Mosaic can handle other file types by associating new file types with helper applications.

Many file formats are predefined. All you need to do is associate a file format with the application that you want to use to read the file format.

To associate a file type with a helper application:

  1. From the Edit menu, choose Helpers.

  2. Select the file type that you want to associate with a helper application and choose the Edit button.

  3. In the Helper Application field, specify the helper application that you want to use to read the selected file type. Click Browse to select the application.

  4. Choose the OK button.

To add a new file type (for advanced users):

  1. From the Edit menu, choose Helpers.

  2. Choose the Add button.

  3. In the Description field, type your own description of the file type.

  4. In the MIME Type field, type the MIME type/subtype of the file type.

    MIME (Multi-purpose Internet Mail Extensions) is a standard system for naming different file formats. When Mosaic retrieves a file from a server, the server provides the MIME type of the file. Mosaic uses the MIME type to determine if the file can be read by Mosaic, or if an appropriate helper application is available to read the file.

    MIME types are available from the list of registered MIME types. Use the MIME type that best describes your file type.

  5. In the Suffixes field, type the filename extension(s) commonly used for the file type. Begin each extension with a period. Separate multiple extensions by spaces.

    For servers that do not provide MIME types, Mosaic uses filename extensions to determine the file format.

  6. Select Binary or Text to specify how the file type is encoded. Most file types are encoded as binary.

  7. Open the How to Handle menu and choose how you want to handle the file type:

    Use Mosaic as a Viewer Open the files in Mosaic.
    Use an SDI-Enabled Helper Open the files with a helper application that is compatible with the Mosaic Software Development Interface. (SDI applications are programs that are specifically designed to work with Mosaic.)
    Use a Helper Application Open the files with a helper application that is not SDI-enabled. This option creates temporary copies of downloaded files, which are deleted when you exit Mosaic.
    Save as a File Save the files without opening them.
    Save and use a Helper Save the files to your disk before they are opened by the program specified in the Helper Application field.

  8. In the Helper Application field, specify the helper application that you want to use to read the selected file type. Click Browse to select the application.

  9. In the Type field, enter the four-letter type code that identifies the format of the file to the Macintosh Finder.

    To find the type code of a file you will need a resource editor, such as ResEdit. To find a type code, open a file of the type you configuring in ResEdit and choose Get Info for <filename> from the File menu. The type code is displayed. If you do not have a sample file, create one using the helper application associated with the file type.

  10. Choose the OK button.