InfoSheet 6:
Cumulus Network/Desktop resolvers

This infosheet gives you information about how Cumulus resolves aliases to image files and how you can customize it to your own needs.

Cumulus internally uses the Macintosh Alias Manager to resolve an alias to an image file. By writing a resolver plug-in you can customize the way Cumulus resolves file references to find the original file. To develop a new resolver to access images on special volumes (e.g. CD-Changer or other storage media) is a possibility to access the files on volumes which are not accessible by using the Macintosh Alias Manager and saves you from patching it.

Cumulus comes with a full path resolver which tries to access the images using the full path name of the file.

When the client user tries to access an image stored in a jukebox connected to the server Cumulus tries to access the image on a local CD-ROM first and prompts the user to insert the CD-ROM into the local drive. If the user cancels the procedure Cumulus Client asks the server if he is able to resolve the alias and the server offers a copy of the image to the client if possible. In the case the user knows that all the images are stored in the jukebox it is possible to install a resolver on the client that always returns an error code indicating the client not to try to access the image on the local CD-ROM and not to display the insert-dialog but to always ask the server for a copy of the image.

The resolver has to be installed in the Resolvers folder in the Cumulus application folder. This is the Cumulus Network (Server) folder on your server or the Cumulus Client folder on your client computers. You can install more than one resolver for Cumulus. The reolver returns one of the following:

1) The resolver can access the file
2) The resolver does not support the file. Cumulus activates the next resolver if available
3) The resolver returns an error code (e.g. useful for accessing images in the jukebox from the
client, see above)

Cumulus asks the different resolvers in alphabetical order. If the first resolver is not able to access the image the second one is asked and so on. If no one of the "external" resolvers can access the image Cumulus uses the internal resolver (Macintosh Alias Manager).

The last "resolver" to be opened is the OPI resolver. This tool is not a resolver at all because it does not resolve the alias but tries to exchange the layout- or sample files with the high resolution files when using the print or the edit functionality of Cumulus. This is why it is only activated if one of the resolvers was able to access the image.

All the OPI "knowledge" was implemented in the adapters (QuarkXPress, Photoshop, ...), in the file filters (EPSF, TIFF) and in the OPI resolver itself. This makes Cumulus even more flexible and easier customizable to the different OPI systems.

When writing a new resolver for accessing a new piece of hardware it is recommended to return the status "not supported" when it is not possible to resolve the alias. In this case another "external" resolver gets the chance to access the image.

There are two different flags specifying the method to use when resolving the alias and whether the resolver should be allowed to bring up a user interface(dialog). Please be careful not to bring up an interface on the server!

The delivered source code for developing a new resolver was implemented in ThinkC. It is possible to use other C compilers like Metrowerks or MPW (Macintosh Programmers Workshop) as well.

Cumulus comes with the source code for a sample resolver plug-in that calls "MatchAlias" to get a list of up to 10 possible matches and lets the user select one of them to be returned to the caller. This sample only reacts on the "ExtensiveSearch" method because the search it implements can take a long time.


If you have further questions please send email:

In the United States:
support@canto-software.com

In Europe and Asia:
support@canto.de

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