Import/Export

The Export/Import display provides client-side integration with external tools. Data can be exported from VisualCommander to a standard file format; that file can then be processed by an external tool. The external tool can produce a similarly-formatted file to provide data to be imported back into VisualCommander.

Conceptual Overview

The Export/Import display provides for the following sequence of events:

1. The user specifies the set of data that should be exported, if any. This is done by creating inputs in the "Export Data" tab of the configuration window, and then connecting those inputs to data points via VisaulCommander's Data Flow window. In addition, the amount and frequency of historical data can be configured.
2. The data is exported, either because the user has clicked the "Export Now" button or the user has configured the display to automatically export at an interval.
3. The display runs an external tool or shell script, as configured in the Processing tab of the configuration window.
4. The external tool (or some other mechanism) writes data to a file that should then be imported.
5. The display reads the import file from a location configured in the Setup tab, either because it has noted that the file has changed or the user has clicked the "Import Now" button.
6. The display associates the data in the import file with outputs that have been pre-configured by the user at the "Import Data" tab in the configuration window. Other displays can then visualize the imported data.

Each major step in the sequence - Export, Import, and Processing - is optional. It's possible to use the display only to export to an external file, without any sort of managed post-processing or import of processed data; it's also possible use it simply to import data from an external source for use within VisualCommander.

Configuration

The Configuration window for the Export/Import display consists of four major tabs, which will be described in order.

The Outputs tab allows for configuration of the data that will be written to the export file. Outputs may be added in one of two ways:

1. If a data point is dragged directly onto the display, an output will automatically be created with the same name as the data point.
2. By clicking the '+' button beneath the table of outputs, a new output can be created by hand with a specific name. A data point can then be connected to that output via the Data Flow window.

Outputs are unordered. They are written to the export file in tab-delimited format; the first row gives the name of each output. Subsequent rows provide the associated data for the output. The first column of the file provides the Julian date associated with that row's data.