A run-time link is a link between groups in which the ports might change at run time. The Data Integration Service determines the ports to link at run time based on policies and parameters.
Create a run-time link between groups of the mapping objects if the ports in the upstream transformation can change at run time. If the ports can change at run time, you cannot link the ports when you design the mapping. Create a run-time link that can use a parameter and a link policy to determine which ports to link at run time.
Create a run-time link in the following situations:
You configure the Read transformation to get columns from the data source or to use a source defined by a parameter.
For example, a Read transformation uses a parameter to change the sources or that get metadata changes from the source at run time. The downstream transformations receive data through ports from a generated port that can change between mapping runs. Create and configure a run-time link to the downstream transformations. At run time, the Data Integration Service connects the ports based on the link policy or the parameter values.
You configure the Write transformation to get columns from the data source or the data object or to use a target defined by a parameter.
For example, a Write transformation defines columns based on an associated data object. The Write transformation uses a parameter to change the target or gets metadata changes from the target at run time. create and configure a run-time link to the Write transformation.
Do not create a run-time link to a Write transformation when you define the target columns based on the mapping flow.
At run time, the Data Integration Service connects the ports based on the link policy or the parameter values and passes the data to the downstream port.
Create a run-time link between groups of transformations if the ports in the upstream transformation can change at run time. The Data Integration Service determines which ports to link at run time based on a parameter, link policy, or both that you define. Run-time links appear as thick lines in the mapping editor.
The following image shows a run-time link between an Aggregator transformation and a Write transformation: