Safari application - MIME type linkage.

This is possibly related to the "Can you tell Safari what app to use to open document links?" post at https://discussions.apple.com/thread/4043799?searchText=Can you tell Safari what app to use to open doc That conversation seems incomplete, and seems to have ended somewhat abruptly with no clear resolution.

The MIME type is correct - that is, the MIME type specified in my MacOS X application's Info.plist file matches that provided by the web server along with the file data content.

The file extension is also correct - that is, the file extension specified in my MacOS X application's Info.plist matches the extension of the filename provided by the server along with the file data content.

We know these match, because:

1) The MIME type and file extensions from this web server work as designed with other browsers and on other platforms.

2) By default, Finder opens files with the given file extension and MIME type in the intended application.

Safari is also configured to 'Open "safe" files after downloading', but this seems to have no effect.

The behavior I observe is that Safari opens a new blank tab (in which it graphically illustrates slam-dunking a monochrome compass into the lower-right corner of the console), saves the data in the Downloads folder, and does nothing else. The user is apparently expected to know that they have to (1) open the downloads folder in Finder (e.g., by clicking on the downloads icon in Safari), (2) manually double-click each downloaded file, thus using Finder to indirectly open the file in the designated application, and then (3) close all the blank white Safari tabs. This operation is obviously cumbersome to the user, as it introduces several more UI operations (mouse movements, mouse button clicks, keystrokes, etc.) and has been determined to be completely unacceptable in terms of end user usability, productivity, and performance, in the context of our web application.

So bottom line - what is the proper mechanism for configuring Safari to automatically open a specific file type (by MIME type, file extension, or both) with a specific application, without requiring additional end user operations?

Assume that this is a generic file type and a generic application. For example, "*.wxyz" files being opened with the "WXYZ File Editor" application.

Assume that the user does not have an admin password.

I need support for this operation on MacOS X versions 10.7 and 10.8, though the available system on which I am testing has MacOS X 10.9.2.

Safari version is 7.0.3 (9537.75.14).

Thanks for your assistance!