Timing and the Other Columns | Requirements Analysis: From Business Views to Architecture


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	Requirements Analysis: From Business Views to Architecture By David C. Hay
	Table of Contents

	Chapter 7. Column Five: Timing

Timing and the Other Columns

Timing and Data

Understanding the structure of data, as revealed in an entity/relationship diagram, does not reveal the true nature of the entities involved. It is in the life historythe succession of statesthat this is revealed. State/transition diagrams show that sequence of states. Entity life histories show how timing (events) determine the passage of entities from one state to another.

Timing and Activities

In the search for understanding of the true nature of the functions of an organization, the event as a stimulus causing functions to occur is the answer. Recall that in several modeling techniques it was significant that communications could be either simple data or messages (triggers, events) causing an action to take place.

Functions can also be divided and organized in many different ways, but the set of event types that can affect a company ultimately must be the basis for any rational organization of those functions.

Timing and Locations

As described in Chapter 6, everything in a company takes place somewhere. Events and state changes are no different, although they are usually located in the same place as the entity types whose states are being changed. More than that, however, location can affect the way we define what constitutes an external event. We have repeatedly said that internal eventsone activity's triggering anotherare not our concern. The problem is when a closely related department is, in fact, in a remote location. If they were in the same place, the activity in one department would trigger the activity in another, but both would be part of a single essential activity, because both were components of a reaction to something happening in the world. If, on the other hand, the organization performing the first action were in New York City and the organization performing the second were in Los Angeles, the trigger would certainly look like an external event to the people in Los Angeles. This has to be accounted for during analysis.

Timing, People, and Organizations

In the cybernetic model of the organization presented in Chapter 5, the main topic is communications, with no distinction being made between simple data and events. One event that was significant, however, was an operation's going outside its operating values (set points). Ultimately, this is the event that requires the management entity to act. Of all the events that management must respond to from the outside world, this is the one internal event that is critical.

The analysis project should clarify which events affect which parts of the organization.

Timing and Motivation

Goals and strategies typically are not expressed in terms of time or the events to which they are responding. Objectives and tactics must be so expressed , however. Business policies and business rules often deal with external events and recommended ways of dealing with them.

One way to discover rules is to study events and determine the decisions made in response to each.


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