Each Widget displays data from a single Data Source.
Some Widget graphical properties are automatically generated from the values in the data.
As a result, it is preferable to start Widget configuration by binding data.
What is data binding ?
When binding data, you are in fact configuring a query to the Data Source.
Internally to Alpana, the result of this query is a table of values which will be used to dynamically change some graphical properties of the Widget.
For example, when you want to see the average temperature by Equipment on a Column Chart, the Widget will draw as many rectangles (columns) as there are Equipments, and the height of the rectangles (Y position) will be a number of pixels proportionate to the average temperature.
Why aggregate Quantities ?
In Dashboard visualization, we want to turn many data points into few simple indicators that allow to take a decision efficiently.
Several data rows will turn into a single shape (this is called “grouping”), and a single data value will be associated to this shape (this is called “aggregating”).
Even if you “know” that for each group your data contains only a single data row right now, your KPI definition needs to account for the fact that there could be many.
You are trending the temperature from a sensor. Right now you know you only have 1 data point at each instant.
So why would you need to choose an aggregation for the Temperature ?
Well, tomorrow you will need to integrate the temperature measurements from 3 sensors.
Then, at each instant you will have 3 data points, but your chart is configured to show only 1 trend.
To solve this, you will need to create an aggregation expression.
Maybe a simple
AVG(Temperature), or maybe something more complex involving Alpana Expressions.