Specifications

Short Description
analysis pattern, a way of capturing how people think about a domain, and a design pattern, a useful. mechanism for accomplishing some system tasks. …

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Content
1
Specifications
by Eric Evans and Martin Fowler
Introduction
One of the nice things about working in Silicon Valley is that almost any time of the year you can
walk around outside while discussing some design point. Due to serious follicle impairment Martin
needs to wear a hat when doing this in the sunshine. Eric was talking to him about the problems of
matching shipping services to the requests customers make and the similar process as the shipper
makes requests to contractors. There was some similarity here that suggested an abstraction. Eric had
been using a model he called “specification” to represent the requirements for a route and to ensure
that cargoes were stored in proper containers. Martin had come across similar problems before. In a
trading system people were responsible for looking at the risk implied by some subset of the bank’s
contracts. Healthcare observations could be made on a population to indicate typical ranges of some
phenomenon type (such as the breathing flow for a heavy smoker in his 60’s). He suggested some
extensions to the model. From that point it was clear that there were patterns…