74 Chapter 4. Software Architecture
4.1 THE NOTION OF ARCHITECTURE
The original meaning of the word architecture, as defined in the Oxford English
Dictionary, is the art or science of building, especially the art or practice of
designing edifices for human use taking both aesthetic and practical factors into
account. It also means a style of building, a mode, manner, or style of construction
or organisations, and structure. Therefore, let’s start the examination of the notion
with buildings.
4.1.1 Architecture in the discipline of buildings
Buildings can be classified according to their main function, or purpose. For
example, houses are for residential accommodation; dovecotes are for housing
doves; lighthouses are coastal towers with lights to warn approaching ships of
dangers, etc. The basic lesson that we can learn from buildings’ architecture is that
the main function of the system is the most important and basic factor and
determines its structure. While the main function of a building largely determines
its structure, other constraints also affect the structural and other features of the
building. For example, each type of building can be further classified by the
structure and its specific usage. Bastel houses are homes in which the residential
quarters are above livestock shelters and storage space. Bungalows are one-storey
houses. Semi-detached houses are two houses joined to form one building.
Terraced houses are a row of connected houses, etc.
While structure in the above sense plays an important role in building, at the
heart of the science and art of architecture are the so-called architectural styles. The
house that my family lives in is not a Georgian house or Victorian house not only
because it is not old enough, but more importantly, because its style is not
Georgian or Victorian. Features of Georgian design include symmetry, simplicity
and classical details such as columns in the classical orders of Doric, Ionic and
Corinthian. The panelled front doors are large, with columns or decorations both
sides and a semi-circular window, known as a fanlight, above. Sash windows,
introduced in the early 18th century, are tall and well proportioned. They have
delicate wooden glazing bars and the panes of glass are all the same size. A typical
example of Georgian houses is the 18th century building the Royal Crescent in
Bath; see Figure 4.1. Victorian houses are those built during the reign of Queen
Victoria from 1837 to 1901. Much of the domestic Victorian housing was modest
and terraced or semi-detached.
Software Design Methodology 75
Figure 4.1 The 18th century crescent of terraced Georgian houses in Bath
The change of architectural styles in history clearly demonstrates the impact
of development of building techniques. When the Normans invaded and conquered
Britain in 1066, they brought the Romanesque style with them. Their skills as
masons and engineers were demonstrated in their massive, solid-constructed
churches and cathedrals. They had perfected the roof-covering technique of
vaulting developed 1000 years earlier by the Romans. This involved the use of
semicircular stone arches extending the length of the roof space to form a barrel
vault. The Norman style has the features that walls are thick, with large smooth-
faced, rectangular dressed stones and an infilling of small stones. Broad buttresses
support the walls. Windows are narrow and semicircular. Doors are surrounded by
semicircular arches, often colourfully decorated with a zigzag and dog-tooth
pattern. Columns are massive circular structures, sometimes covered with
ascending spirals or diamonds and with circular bases sitting on square footings.
Capitals are either square with cushion-type decoration or circular. Norman
architects had encountered difficulties when creating intersections between aisles
of different widths. Their early English successors solved these problems either by
constructing pointed arches because the height of a pointed arch is not determined
by its width, or by raising the level of the springers (the bottom stones) on the
narrower semicircular arch. Churches after the 12th century had lighter, thinner
structures with aisles and naves of varying width. To support the increasingly high
and thin walls, the flying buttress was introduced, which transferred the downward
thrusts to supports away from the main inner wall. This allowed structures to have
larger windows because the walls took less of the overall weight. Because of the
use of pointed arches, the width of doors no longer needed to relate to the height of
the arch. Entrances acquired a more graceful appearance. These are the basic
characteristics of Gothic church architecture. During the 14th century, architects

Get Software Design Methodology now with O’Reilly online learning.

O’Reilly members experience live online training, plus books, videos, and digital content from 200+ publishers.