System Scale

General

The notion of scale encompasses both quantitative and qualitative aspects.

The quantitiative aspects address how parameters change as another parameter changes. For information systems, typical parameters are users, data size. For physical systems, typical parameter are mass, spacial dimensions, energy. Scaling consideration such as Reynold's Numbers, mass-height ratios, and heat-volume ratios can provide useful and deeper insights and guidance into seemingly disparate phenomena. (TBD ref from Sandia)

The qualitative aspects of scale address how behaviour or characteristics change as dimensions change. They consider how dimension affects form and behaviour. Indeed, as dimensions change, rules may break down so that new concepts and paradigms come into play.

The following address the qualitative aspects relevant to information systems.

Scale Model

It is useful to have a model of the different scales in information systems. The following is based on Corba Design Patternsby by Mowbray, Malveau. There are other hierarchies. Living Systems presents a hierarchy for biological/social sytems.

0	Datum	The data level assigns primitive meaning to patterns. Program statements and fields reside at this level.
1	Object	The object level assembles data and logic into meaningful functionality. Classes and tables reside at this level.
2	Package	The package adresses microarchitecture. It assembles objects and classes into functional patterns. This is generally the level discussed in the patterns book by Gamma et al. Packages and libraries resides at this level.
3	Framework	The framework addresses macroarchitecture. The framework assembles objects and classes into services. The goal is reuse of components and design.
4	Application	Aplications assemble objects, packages, and one or more frameworks into a program. The goal is to provide specific functionality.
5	System	The system level assembles applications into an integrated solution.
6	Enterprise	The enterprise level comprises the systems that a enterprise uses. Note that enterprise has control over its systems.
7	Global	The global address multiple enterprises. it addresses issues that flow across enterprise boundaries. Concerns at this level are standards for languages and data.

Aspects

Emergence

As scale changes, new capabilities can appear. A simple example is crystal symmetries that occur at the lattice level. Biology is full examples where organs systems take on secondary uses, for example the use of the tongue and lips in speach. Another example is the emergence of the web from various networking and formating standards.

Binding

Stronger forces bind quicker. The may not be apparant at higher scales. At the scale of every day life we are most aware of the relatively weak gravitional force. We seldom see the strong forces as they have bound together at nuclear and elementary particles scales.

Fractiles

The notion of fractiles have been applied to geometries where the same pattern is applied across multiple scales. Clouds and coastlines can exhibit such geometry. Simple operations can spawn very rich and complex patterns. Note that in nature, the fractile breaks down after several scales. Mathematically, it can be applied indefinetly.

Software can use leverage iterative and recursive techniques to accomplish rich behaviour.

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