3.3.1 Basic operation of FlowDesigner

A node is a processing unit that processes data. First, an example of a node is shown in Figure 3.2. The green part enclosed with a rectangle is the node, and the node’s name is displayed in the center. In this example, PostFilter is displayed. The name node_Postfilter_1 displayed below the node is an instance name of the node. The same node, when applied multiple times, is named after the order in which it is created. For example, node_Postfilter_2, node_Postfilter_3. It is useful to distinguish each node. Each node may have multiple terminals for inputs and outputs of data processed. The black points on the right and left of the node are the terminals. Those on the left are input terminals and on the right are output terminals. Terminals are named or unnamed depending on the cases. All terminals are named in this example. A node has at least one output terminal though there are no input terminals in some cases. For example, the constant node included in FlowDesigner by default does not have inputs but one output.

Figure 3.2: Overview of node

Data processing flows are defined by positioning multiple nodes and connecting the terminals of the nodes. A series of connected nodes is called a network, and creating a network itself is programming. Networks can be saved using the file save menu. Once a network is saved, it can be loaded by FlowDesigner anytime. When opening a saved file with a text editor, an XML-like description is seen. The user may edit such a file directly by a text editor once they get used to HARK.

Since some nodes have properties, the user can modify the processing of the nodes in detail by setting their property values. To set property values, move the mouse cursor over a node and left-double click on it. The setting DIALOG window opens and the user may input property values using the keyboard, or select values. Since there are data types for property values, the user is required to set data types and values as a pair. For details of the data types, see the chapter Data Type. Select data types from the pull-down menu. For values, the user may enter them with the keyboard or select values from the pull-down menu depending on the case.

Figure 3.3: Overview of property