Using the SCOadmin internationalization facility

Understanding message catalogs

The SCOadmin internationalization facility builds on top of XPG/3 message catalogs by adding these features:

one-step lookup of messages
grouping of messages by modules
language-independent message catalog support
simple syntax for module ID files and message description files
automatic loading of message catalogs corresponding to a given module
automatic configuration of default messages
ability to format messages in the manner of sprintf(3S)

XPG/3 message catalogs are created by gencat(1). Each message catalog can contain one or more sets of messages. The message catalogs can be further grouped by archives (groups of related catalogs) and installed on the runtime system. A program wishing to look up a message uses the catopen(3C) function to open the desired catalog and the catgets(3C) function to look up the desired message within the desired set, as well as to supply a default message to use if lookup is not successful or the default locale is in effect. This scheme requires the programmer to juggle many pieces of information (archive and catalog name, set number, message number, and default message) and manage the opening and closing of message catalogs. If the message needs additional information, it has to be formatted in an extra step, typically using sprintf(3S). For example, a message such as:

   "Unable to open file %s"

could be used, but it would need to be passed to sprintf along with the name of the file in order to create the final string.

Overview of message catalogs

SCOadmin uses the XPG/3 framework but allows the programmer to look up a message with one call, which takes one parameter, a symbolic message ID, along with any other parameters needed for sprintf-style formatting. Each message ID belongs to a module known to SCOadmin, which corresponds to a message set within a message catalog. The SCOadmin internationalization facility divides the message ID into a module ID and a specific message ID, and opens the needed message catalog (if it was not open before) to get the requested message. If the catalog can't be loaded, or the default locale is in effect, the default message associated with the message ID is returned. If there are any additional arguments, sprintf(3S) is called to format the final message.

The information required by the SCOadmin internationalization facility to perform message lookup is listed below:

definition of modules, including the module name, and the archive, message catalog, and message set to which each module belongs. This information goes in a module ID file.
definition of messages within each module, which includes the module name, specific message name, and a default message. This information goes in a message description file.

This information is compiled by mkcatdecl(1) into message declaration files which must be included in the program that wishes to use the messages from a particular module. Each file defines the message IDs corresponding to the messages from one module, so that the program can use these IDs for message lookup. Message declaration files can be generated for C, Tcl. or both languages.

mkcatdecl also generates files that can be used as a source file for gencat(1) to generate a message catalog. This catalog can then be installed on the target system so that the SCOadmin internationalization facility can use it to look up messages.

When you use the SCOadmin internationalization facility to localize software for more than one locale, you will have multiple message description files for each module. Use the message description files corresponding to the default locale to generate your message declaration files, since they will contain default messages that correspond to your desired default locale. For non-default locales, generate only message catalogs. mkcatdecl has an option to compare two message description files for the same module to ensure that they both contain the same set of message IDs.

Next topic: Creating a module ID declaration file
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UnixWare 7 Release 7.1.4 - 27 April 2004