Component Guide I: Atomic Components

Overview

Nova models are constructed out of components, which are visual tokens that are placed on the Model Canvas.

To place a component on the model canvas:

• Click the desired component on the component pallet; components are identified by their icons and tool tips that appear when the mouse hovers over a component.
• Click on the model canvas at the location chosen for this component; do not drag the component from the component pallet.
• When prompted, provide a component name (a default name will be provided if you choose not to provide one).

A new component requires two actions to integrate it into the model:

• Connections must be made to components with which this component will interact; and
• The new component must be programmed; in the simplest case, this involves providing a component equation that defines the value represented by this component. Specific programming tasks for each component type will be described below.

Component Types

Atomic Components

Tranditional systems dynamic components State (subdivided into Stock Stock+Flow, Sequence, Sequence+Flow, and Store), Flow, and Term; along with Command and Event.

Containers

Nova containers consist of Chips and 5 types of aggregators; a Chip holds a single instance of Capsule, used as a submodel while aggregators hold multiple Capsule instances, possibly of different types. Each aggregator type implements a different topology for its elements. The aggregator components are AgentVector, CellMatrix, NodeNetwork, SimWorld and NetWorld.

Controls and Displays

These include Table, Linechart, Scatterchart, Barchart, Histogram, Slider, Spinner and Toggle.

Special

These are special purpose components consisting of Code Chip and Comment.

Plugins

These are extensions to the component set and have various functions.

Component Properties

Each component has an associated Properties Pane (PropPane) that provides the means for programming the component (and in some cases specifying connections.) The PropPane is opened by selecting the component. PropPanes allow you to define the value represented by a component, set pin connections, determine what is displayed (in the case of Graphs and Tables), calibrate (in the case of Sliders and Spinners) and set any other property required by the component. Specific properties are part of the component descriptions below.

Defining Component Values

Most components require a formula or program to specify their values. This formula is a NovaScript expression or sequence of expressions entered into a text area on the PropPane. Component value formulas can make use of the underlying Javascript language to build somewhat complex algorithms for computing the value.