Construction Operations Management Management of Information Systems

Data Flow

Data flow analysis is a well established methodology and has been used for management

information flow in construction organisations. Other exponents of the data flow concept have

modelled the regional office and site based information systems of a large contractor and an

operational integrated data management system for a house building organisation.

Systems analysis develops understanding of the flow of data through a system. Data flow

diagrams are produced by analysing the progressive transformation of data throughout the

system. Each transformation represents a process which is shown as a circle in the data flow

diagram and lines joining the circles represent the flow of data between processes. Data flow

diagrams (DFDs) are made up fiom four symbols as shown in Figure 1.1 together with an

illustrative example. These four symbols enable a picture of the system to be drawn without

commitment as to how it will be implemented. A data dictionary containing a concise

definition of each element is constructed as data are identified. When the system has been

totally described in terms of data, data transformation processes shown in the data flow

diagram are organised into a topdown hierarchical control diagram. Finally the functions

performed in each process are described using structured English to aid program coding.

An output orientated design approach has the advantage of producing minimal systems in

which the precise scope of a system is defined together with the correct maintenance of data.

Everythmg that appears as output has to be entered into the system at some point as input or

has to be generated fiom some input. By working backwards fiom the outputs the minimum

database and inputs for a new system can be determined. The final systems must produce

answers that agree with the real world and any data that is required to be accurate must be

frequently used. A feedback mechanism must ensure that data is constantly changing to reflect

the updated position.