By default, an output port in a Custom transformation depends on all input ports. However, you can define the relationship between input and output ports in a Custom transformation. When you do this, you can view link paths in a mapping containing a Custom transformation and you can see which input ports an output port depends on. You can also view source column dependencies for target ports in a mapping containing a Custom transformation.
To define the relationship between ports in a Custom transformation, create a port dependency. A port dependency is the relationship between an output or input/output port and one or more input or input/output ports. When you create a port dependency, base it on the procedure logic in the code.
To create a port dependency, click Custom Transformation on the Ports tab and choose Port Dependencies.
For example, create a external procedure that parses XML data. You create a Custom transformation with one input group containing one input port and multiple output groups containing multiple output ports. According to the external procedure logic, all output ports depend on the input port. You can define this relationship in the Custom transformation by creating a port dependency for each output port. Define each port dependency so that the output port depends on the one input port.
To create a port dependency: