Data Source (BDataSourceBlock)

This block supplies data to an algorithm. In addition to algorithms, a request for data may also come from a variety of sources, such as graphics bindings and alerts.

This block supports both real-time values and trend requests if the underlying data support them.

This block can override some properties of the request. In the process, it generates a modified request for data and supplies the results to the blocks that are linked to its out property.

Figure 78. Data Source Block properties

To view these properties, double-click the block on the Wire Sheet or the block name in the Nav tree.

Property	Value	Description
Out	read-only value slot	Displays the value or trend resolved for the block.
Fallback In	value slot	Links from the output of other logic blocks or data sources to supply an alternate input source. If the data source is not available for a node, the framework uses this alternate input. The input could be another data source object like this one, or it could be something, such as a constant. The framework does not use the `Fallback Input` if this data source is available.
Use Request Aggregation	`true` or `false` (default)	Determines the aggregation method to use. While the Data Definition associated with each tag defines the default aggregation method, an incoming request from a data source block can override this default aggregation method. `true` causes the framework to use the function defined by the `Aggregation` property, if defined in the request. `false` causes the framework to use the algorithm’s `Aggregation` property.
Use Request Data Filter	`true` or `false` (default)	Determines the data filter method to use. `true` uses the `Data Filter` property defined in the request. `false` uses the `Data Filter` value as defined in the block. If the `Data Filter` on the Data Source Block is not defined, it has no effect on the result of processing the request.
Use Request Rollup	`true` or `false` (default)	Determines the request rollup method to use. The Data Definition associated with each tag defines the default method to roll up data. An incoming request from a data source, rollup, sliding window or today builder block may override this default method. `true` causes the framework to use the function defined by the `Rollup` property if defined in the request, else the algorithm’s `Rollup` property. `false` causes the framework to use the function defined by the block’s `Rollup` property if defined, else the Data Definition’s `Rollup` property if a Data Definition exists for the tag, else the default `First` function.
Use Request Totalize	`true` or `false` (default)	Determines the function to use when calculating a total. `true` causes the Data Source Block to use the value of the `Totalize` property if defined in the request, else it uses `Totalize` = `true`. `false` causes the block to use the value of the block’s `Totalize` property when the `Totalize` property is configured. If the `Totalize` property on the block is not defined, the block uses the default value (`true`).
Aggregation	value ( defaults to `First`)	Configures the default function used to combine values from multiple data sources into a single value when the block's Use Request Aggregation property is `true`. This applies to both value and trend requests. If aggregation is not enabled in the binding/settings window, the aggregation value defined in the Data Definition applies to all chart bindings, reports and tables. `And` returns the logical “and” of Boolean values. `Avg` returns the statistical mean, which is determined by calculating the sum of all values and dividing by the number of values. `Count` returns the total number or quantity of values in a combination. If you request this value on a binding in a PX view, the system counts the number of values based on the properties defined by the data source block and the algorithm’s Property Sheet. `First` returns the first value in the combination. `Last` returns the last value in the combination. `Max` returns the highest value in the combination. `Median` returns the value in the middle of a sorted combination—the number that separates the higher half from the lower half. `Min` returns the lowest value in the combination. `Mode` returns the statistically most frequently occurring number in the combination. `Or` returns the logical “or” of Boolean values. `Range` returns the statistical difference between the largest and smallest values in the combination. `Sum` adds together all values in the combination resulting in a single value. `Load Factor` returns the average value divided by peak value. `Std Dev` returns the standard deviation of the values in the combination.
Data Filter	optional NEQL predicate (property) or ORD parameter (dataFilter=predicate)	Identifies data sources in the subtree of the request node. When a predicate accepts a node that contains the desired data, the system does not search the node’s subtree for additional values (including the root node).
Rollup	check box (if optional, and) drop-down list or ORD parameter (when configured in the data definition, defaults to `First`, when configured elsewhere, defaults to the value as defined in the Data Definition); rollup=option	Configures the default rollup function passed through the algorithm when the Data Source block `Use Request Rollup` property is set to `true`. If rollup is not enabled in the binding/settings window, the rollup value configured in the Data Definition applies to all chart bindings, reports and tables. `And` returns the logical “and” of Boolean values. `Avg` returns the statistical mean, which is determined by calculating the sum of all values and dividing by the number of values. `Count` returns the total number or quantity of values in a combination. If you request this value on a binding in a PX view, the system counts the number of values based on the properties defined by the data source block and the algorithm’s Property Sheet. `First` returns the first value in the combination. `Last` returns the last value in the combination. `Max` returns the highest value in the combination. `Median` returns the value in the middle of a sorted combination—the number that separates the higher half from the lower half. `Min` returns the lowest value in the combination. `Mode` returns the statistically most frequently occurring number in the combination. `Or` returns the logical “or” of Boolean values. `Range` returns the statistical difference between the largest and smallest values in the combination. `Sum` adds together all values in the combination resulting in a single value. `Std Dev` calculates the standard deviation of the values in the combination. `Load Factor` calculates the average divided by peak (Max) value.
Totalize	`true` or `false` (default)	Determines if the totalized or delta values should be calculated.
Unit conversion	optional	If set, the system converts values supplied using the units defined in the data policy of the data source to the units defined by this property.

Processing with Use Request Aggregation

When Use Request Aggrigation is false and Aggregation is not configured, the block uses the aggregation function defined in the applicable Data Definition. If there is no Data Definition, the block uses the default First function. When Use Request Aggrigation is false and Aggregation property is configured, the block uses the Aggregation property value. When Use Request Aggregation is true, the block uses the aggregation function defined in the request (Analytic Proxy Ext, Analytic Binding, etc.), unless the request does not specify the aggregation function, in which case the block uses the Algorithm’s Aggregation property value.

The following table may help to determine when each value applies.

Data Definition Aggregation	Data Source Block Use Request Aggregation	Data Source Block Aggregation	Request Aggregation	Algorithm Aggregation	Actual Aggregation Function
Unconfigured	False	Unconfigured	Sum	Max	Defaults to First
Last	False	Unconfigured	Sum	Max	Last
Last	False	Avg	Sum	Max	Avg
Last	True	Avg	Sum	Max	Sum
Last	True	Avg	Unconfigured	Max	Max

Processing with Use Request Rollup

When Use Request Rollup is false and Rollup is not configured, the block uses the rollup function defined in the applicable Data Definition. If there is no Data Definition, the block uses the default First function. When Use Request Rollup is false and Rollup property is configured, the block uses the Rollup property value. When Use Request Rollup is true, the block uses the rollup function defined in the request (Analytic Proxy Ext, Analytic Binding, etc.), unless the request does not specify the rollup function in which case the block uses the Algorithm’s Rollup property value.

The following table may help to determine when each value applies.

Data Definition Rollup	Data Source Block Use Request Rollup	Data Source Block Rollup	Request Rollup	Algorithm Rollup	Actual Rollup Function
Unconfigured	False	Unconfigured	Sum	Max	Defaults to First
Last	False	Unconfigured	Sum	Max	Last
Last	False	Avg	Sum	Max	Avg
Last	True	Avg	Sum	Max	Sum
Last	True	Avg	Unconfigured	Max	Max