[archive] External data items

[Migrated content. Thread originally posted on 14 May 2003]

Does anyone have a feel for the use of "external data items"? Is it better to use the linkage section or external data items to pass data between called modules? Is there a downside to their use?


Ted

External Data is useful when passing static data like system parameters, user profiles, window/object handles, etc where the data is not going to change very often. When data is amended then it is instantly available to the current processes - e.g. screen colours per user can be available to all the programs which display screens and can be amended to immediate effect.

I have found 2 major drawbacks.
a) You need to copy the data if a process needs it locally, which is ok if using some data elements but becomes combersome when using a lot.
b) The major draw back is when the overall size of the external data is changed then ALL the programs need compiling and distributing, otherwise the runtime gives an error.

Hope this is helpful.

SR