Natural for OpenVMS Version 6.3.12 for OpenVMS
 —  Programming Guide  —

Portable Natural Generated Programs

As of Natural Version 5, Natural generated programs (GPs) are portable across UNIX, OpenVMS and Windows platforms.

This document covers the following topics:


Compatibility

As of Natural Version 5, a source which was cataloged on any Natural-supported UNIX, OpenVMS and Windows platform is executable with all of these Open Systems platforms without recompilation. This feature simplifies the deployment of applications across Open Systems platforms.

Natural applications generated with Natural Version 4 or Natural Version 3 can be executed with Natural Version 5 or above without cataloging the applications again (upward compatibility). In this case, the portable GP functionality is not available. To make use of the portable GP and other improvements, cataloging with Natural Version 5 or above is required.

Command processor GPs are not portable. The portable GP feature is not available for mainframe platforms. This means that Natural GPs which are generated on mainframe computers are not executable on UNIX, OpenVMS and Windows platforms without recompilation of the application and vice versa.

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Endian Mode Considerations

As of Natural Version 5, Natural acts as follows: Depending on which UNIX, OpenVMS or Windows platform it is running, Natural will consider the byte order in which multi-byte numbers are stored in the GP. The two byte order modes are called "Little Endian" and "Big Endian".

The UNIX, OpenVMS and Windows platforms use both endian modes: Intel processors and AXP computers have "Little Endian" byte order, other processors such as HP-UX, Sun Solaris, or RS6000 use "Big Endian" mode.

Natural converts a portable GP automatically into the endian mode of the execution platform, if necessary. This endian conversion is not performed if the GP has been generated in the endian mode of the platform.

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ENDIAN Parameter

In order to increase execution performance of portable GPs, the profile parameter ENDIAN has been introduced. ENDIAN determines the endian mode in which a GP is generated during compilation:

DEFAULT The endian mode of the machine on which the GP is generated.
BIG Big endian mode (high order byte first).
LITTLE Little endian mode (low order byte first).

The values DEFAULT, BIG and LITTLE are alternatives whereby the default value is DEFAULT.

The ENDIAN mode parameter may be set

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Portable FILEDIR.SAG and Error Message Files

As of Natural Version 6.2, the file FILEDIR.SAG and the error message files are platform independent. Hence, it is possible to share common FUSER system files among different Open Systems platforms. For example, it is possible to copy sets of Natural libraries from one Open Systems platform to another with operating system copy procedures. However, it is not recommended to share FNAT system files. For more information about the portable FILEDIR.SAG, refer to Portable Natural System Files in the Operations documentation.

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