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Defining Field Names and Identifiers
A field identifier (fieldid) is defined (with typedef) as a FLDID (FLDID32 for FML32), and is composed of two parts: a field type and a field number. The number uniquely identifies the field.
A field number must fall in one of the following ranges:
Field number 0 and the corresponding field identifier 0 are reserved to indicate a bad field identifier (BADFLDID). When FML is used with other software that also uses fields, additional restrictions may be imposed on field numbers.
The BEA Tuxedo system conforms to the following conventions for field numbers.
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FML Field Numbers |
FML32 Field Numbers |
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|---|---|---|---|
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Reserved |
Available |
Reserved |
Available |
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1-100 |
101-8191 |
1-10,000, |
10,001-30,000,000 |
Applications should avoid using the reserved field numbers, although the BEA Tuxedo system does not strictly enforce applications from using them.
The mappings between field identifiers and field names are contained in either field table files or field header files. If you are using field table files you must convert field name references in C programs with the mapping functions described later in this section. Field header files allow the C preprocessor (cpp(1) in UNIX reference manuals) to resolve name-to-fieldid mappings when a program is compiled.
The functions and programs that access field tables use the environment variables FLDTBLDIR and FIELDTBLS to specify the source directories and field table files, respectively, that are to be used. (FLDTBLDIR32 and FIELDTBLS32 are used for the same purpose with FML32.) You should set these environment variables as described in Setting Up Your Environment for FML and VIEWS.
The use of multiple field tables allows you to establish separate directories and/or files for separate groups of fields. Note that field names and field numbers should be unique across all field tables, since such tables are capable of being converted into C header files, and field numbers that occur more than once may cause unpredictable results.
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Copyright © 2000 BEA Systems, Inc. All rights reserved.
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