Building Chart Dataset

Charts provide several generic ways of fetching data from Iotellect Server unified data model and using this data to build chart's dataset.

This section covers chart properties that are related to fetching source data and building chart's dataset.

Data Source Type

This basic parameter defines what kind of data should be used to build a chart. There can be three options:

Variable. Use data from variable changes history and real-time variable changes to build and dynamically update the chart.
Event. Use data from event history and new event occurrences to build and dynamically update the chart.
Custom Data. Use custom tabular data to build a chart.

Custom Data is supported by all chart types. Variable and Event data source types are available only in charts that are natively designed for time series data (e.g. line chart).

Variable Name:	sourceType
Records:	1

Record Format:

Field Name	Field Type	Field Description
source	Integer	Data Source Type

Source Variables

This property defines what data is used to build a variable-based chart. Every line in the source variables table defines one or more data series to be shown on the chart. Thus, a single chart may show changes of different values, and even values calculated from data of different variables.

Variable Name:	variableData
Records:	1

Record Format:

		Variable Series Expression Resolution Environment:
Field Name	Field Type	Field Description
name	String	Name. Name of data series indicated on the chart. Series name can be an expression or just a string constant.
context	String	Context. Server context defining the location of the variable. For charts located within relative dashboards, this value should be set to a single dot (`.`) , in order to indicate that the variable is located in the context for which the dashboard was opened.
variable	String	Variable. Variable from which to take the data.
expression	String	Expression. Expression used to calculate data values. In most cases it should include references to the variable value.
		Default Context	Specified by series Context setting.
		Default Data Table	Value of variable specified by series Variable setting.
		Default Row	0 (or dynamic if series propagation is enabled)
		Environment Variables	Standard variables only.
customTimestampExpression	String	Custom Timestamp Expression. An optional Expression used to calculate timestamps for each data sample. In most cases it should include a reference to a historical variable's value cell that contains date/time associated with historical data sample. If this expression is not specified, a timestamp of each historical variable value is date/time when it was stored in server's database.
		Custom Timestamp Expression Resolution Environment:
		Default Context	Specified by series Context setting.
		Default Data Table	Value of variable specified by series Variable setting.
		Default Row	0 (or dynamic if series propagation is enabled)
		Environment Variables	Standard variables only.
propagate	Boolean	Propagate. Create a separate data series for every record of source variable. See series propagation for details.
aggregation	Integer	Aggregation. Tells what to do if several data values exist for a specific time range. Possible choices are calculate an average, take minimal or maximal value, calculate a sum of all values, or take first/last value for the period.
types	Integer	Type. Data series type.

Source Events

This property defines what data is used to build an event-based chart. Every line in the source events table defines one data series to be shown on the chart. Thus, a single chart may show changes of different values, and even values calculated from the data of different events.

Variable Name:	eventData
Records:	1

Record Format:

		Variable Series Expression Resolution Environment:
Field Name	Field Type	Field Description
name	String	Name. Name of data series indicated on the chart. Series name can be an expression or just a string constant.
context	String	Context. Server context defining event to take the data from.
event	String	Event. Event from which to take the data.
expression	String	Expression. Expression used to calculate data values. In most cases it should include references to the cells of event Data Table.
		Default Context	Specified by series Context setting.
		Default Data Table	Data table of the event specified by series Event setting.
		Default Row	0
		Environment Variables	Standard variables only.
customTimestampExpression	String	Custom Timestamp Expression. An optional Expression used to calculate timestamps for each data sample. In most cases it should include a reference to a cell of event Data Table that contains date/time when an event has actually happened. If this expression is not specified, a timestamp of each historical event is date/time when it was stored in server's database.
		Custom Timestamp Expression Resolution Environment:
		Default Context	Specified by series Context setting.
		Default Data Table	Data table of the event specified by series Event setting.
		Default Row	0
		Environment Variables	Standard variables only.
aggregation	Integer	Aggregation. Tells what to do if several data values exist for a specific time range. Possible choices are calculate an average, take minimal or maximal value, calculate a sum of all values, or take first/last value for the period.

Include Historical Data

This property specifies whether an variable-based and event-based chart will include historical data, i.e. events and variable value changes that occurred before the chart was built. If enabled, the chart will load historical data according to the selected Limit Time Range option (Full History, Last Values, or Date Range).

Estimate memory consumption that may be caused by loading historical data according to Limit Time Range and Time Range options. Loading a huge amount of historical data may cause server failure or degraded performance.

Variable Name:	useHistoricalData
Records:	1

Record Format:

Field Name	Field Type	Field Description
useHistoricalData	Boolean	Include Historical Data

Include Real-Time Data

This property specifies whether an variable-based and event-based chart will be dynamically updated with real-time data. If enabled, the chart will update according to the selected Limit Time Range option (only Full History or Last Values). The Date Range option of Limit Time Range is not supported for real-time updates.

Variable Name:	useRealTimeData
Records:	1

Record Format:

Field Name	Field Type	Field Description
useRealTimeData	Boolean	Include Real-time Data

Aggregation Time Period

Time unit defines resolution for variable-based and event-based charts. Only one data value per time unit is shown on the chart. For example, if time unit for Event chart is Day and several events occurred during a certain day, data for only one event for this day (the latest one) is shown on the chart.

Charts use Aggregation parameter defined in Source Variables / Source Events to figure out how to group multiple original values into a single dataset value for every time unit.

Available Time Units: Year, Quarter, Month, Week, Day, Hour, Minute and Second.

Variable Name:	aggregateTimePeriod
Records:	1

Record Format:

Field Name	Field Type	Field Description
aggregateTimePeriod	Integer	Time Unit

Limit Time Range

This property is relevant for variable-based and event-based charts. Supported values are:

Full History. All historical values will be loaded and displayed.
Last Values. Chart data will include only events and variable value changes that have occurred only within a certain time before the chart is built, as specified by the Time Range property.
Date Range. Chart data will only include values that were obtained within a time range specified by Start Date and End Date properties.

Disabling limited time range will force the server to load all available event/variable history from database into memory in order to prepare chart dataset. This may cause very high memory consumption and lead to server failure of degraded performance!

Variable Name:	limitTimeRange
Records:	1

Record Format:

Field Name	Field Type	Field Description
limitTimeRange	String	Limit Time Range

Time Range

This option is available only if Limit Time Range setting is enabled. It specifies maximum age of historical data to be used by the chart.

Setting a long time range will force the server to load a sufficient part of event/variable history from database into memory in order to prepare chart dataset. This may cause very high memory consumption and lead to server failure of degraded performance!

Variable Name:	timeRange
Records:	1

Record Format:

Field Name	Field Type	Field Description
timeRange	Long	Time Range

Start Date

Low bound timestamp of displayed historical values range. Available if Limit Time Range is set to Date Range.

Variable Name:	startDate
Records:	1

Record Format:

Field Name	Field Type	Field Description
startDate	Date	Start Date

Property name: startDate

Property type: Date

End Date

High bound timestamp of displayed historical values range. Available if Limit Time Range is set to Date Range.

Variable Name:	endDate
Records:	1

Record Format:

Field Name	Field Type	Field Description
endDate	Date	End Date

Source Data

The source data table used for building custom-data-based charts.

Variable Name:	sourceData
Records:	1

Record Format: dynamic

Source Data Bindings

A set of expressions used to retrieve data from Source Data's records and build the resulting chart dataset. This property is also valid only for charts based on custom data.

Variable Name:	dataBindings
Records:	1

Record Format: differs for different charts

Auto Load Dataset

When True, the chart will be redrawn whenever any parameter in the data group is changed. By setting it to False, the chart will redraw only when the updateDataset() function is called in the chart context.

Variable Name:	autoLoadDataset
Records:	1

Record Format:

Field Name	Field Type	Field Description
autoLoadDataset	Boolean	Auto Load Dataset

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