Mapping Data Streams
Using the mapping tool, you can connect a new data source to a preexisting stream. The mapping tool will not only set up the connection but it will also help you to specify how fields in the new source will replace those in the existing stream. Instead of re-creating an entire data stream for a new data source, you can simply connect to an existing stream.
The data mapping tool allows you to join together two stream fragments and be sure that all of the (essential) field names match up properly. In essence, mapping data results simply in the creation of a new Filter node, which matches up the appropriate fields by renaming them.
There are two equivalent ways to map data:
Select replacement node. This method starts with the node to be replaced. First, you right-click the node to replace; then, using the Data Mapping > Select Replacement Node option from the pop-up menu, select the node with which to replace it.
Map to. This method starts with the node to be introduced to the stream. First, right-click the node to introduce; then, using the Data Mapping > Map To option from the pop-up menu, select the node to which it should join. This method is particularly useful for mapping to a terminal node. Note: You cannot map to Merge or Append nodes. Instead, you should simply connect the stream to the Merge node in the normal manner.
Data mapping is tightly integrated into stream building. If you try to connect to a node that already has a connection, you will be offered the option of replacing the connection or mapping to that node.