Beware Of Migrationalism

2006-11-20 10:36  i859    [permalink]

When ordering changes to the system, the customer may be tempted to construct the ChangeRequest using declarations like "remove this" and "change that to this". In essence, this will contain the information about what is required to change, but in general will not be a clear guide to where to alter the system.

When starting from a certain perspective of the system, which may or may not be a complete view of all the functions of the application, and describing the migration to a new view of the system with some functions altered, the description will only contain the effect on elements of the system that were envisioned in this primary perspective of the system. I call this [[migrationalism]].

So my advice is to explain this to the customer, and that a migrationalist ChangeRequest might lead to incorrect implementation of the changes, and may impact more functions than requested. Ask to revise the ChangeRequest into a proposition of how the revised system should work, without referring to the current operation of the system, optionally only describing part of the system that should undergo the changes. I call this [[propositionalism]].

A description of a system and it's functions is a more independent document. It leaves it up to the architects and developers of the system to compare it to the current build-up of the system and determine where it is best to alter the system to reflect the changes as described in the propositionalist ChangeRequest.

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