Minimising Problems for Future Upgrades

PML Customisation User Guide

Introduction : Minimising Problems for Future Upgrades

When future versions are released, the product documentation will identify which macro files (Form, Object, Function, Command macro) and which parts of the directory hierarchy have been modified. You must then decide on one of three courses of action for dealing with any customised Appware which you may have been using:

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Run your existing Appware, thereby ignoring any enhanced features which may have been incorporated into the standard versions.

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Revert to using standard Appware instead of your customised versions.

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Update your customised Appware to take advantage of any enhanced features now available.

In order to minimise any problems resulting from updating your customised Appware, you should adopt the following key principles as part of your customisation policy:

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The directory which holds the Appware files associated with your Applications is divided into two main areas: a standard product area and a user area. You should make changes only in the User area using only copies of the standard Application macros.

Warning: You should never modify the original files, so that you can always revert to using these if things go wrong.

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The environment variable PMLLIB is a search path which must be set to the directory or list of directories under which user-defined PML Functions, objects and forms are stored. The directory specified can contain sub-directories which will automatically be scanned by PML.

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When writing your own PML Appware, follow the styles and conventions used in the AVEVA standard AppWare.

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Make sure that the names of any new objects, forms and functions which you create cannot conflict with the names of any standard AVEVA Appware which may be used in the AVEVA Applications. You should prefix the names of your objects, forms and global variables with a suitable code to distinguish them from AVEVA names. For example, a company XYZ could choose to start all form and global variables names with the characters XYZ.