After you add and configure source, target, and transformation objects in a mapping, complete the mapping by connecting the mapping objects. You connect mapping objects through the ports. Data passes into and out of a transformation through the following ports:
Receive data and pass it unchanged.
Every source instance, target instance, mapplet, and transformation contains a collection of ports. Each port represents a column of data:
Sources provide data, so they contain only output ports.
Targets receive data, so they contain only input ports.
Mapplets contain only input ports and output ports.
Transformations contain a mix of input, output, and input/output ports, depending on the transformation and its application.
To connect ports, you drag between ports in different mapping objects. The Designer validates the connection and creates the connection only when the connection meets link validation and concatenation requirements.
You can leave ports unconnected. The Integration Service ignores unconnected ports.