A meta-node can be seen almost as a function of a workflow. A function though needs input parameters, since it might ran under different contexts for different workflows or users. The “Quick Form” category offers a number of nodes to implement different types of input parameters in a meta-node.
Let’s suppose, for example, that we want to parametrically change how to calculate the cross table values from the “Crosstab” node. That is, we want to calculate the cross table values for data column “sex” and another data column of choice.
To do that, we inserted a “String Input” node from the “Quick Form” category in the meta-node (see figure below). The “String Input” node generates a workflow variable of type string. We named this workflow variable “parameter” (as a function parameter) and we gave it a default value “income”. We then used the newly created workflow variable “parameter” to select the column in the “Crosstab” node configuration window. If we run the workflow, now the default cross table shows values for data columns “sex” and “income”. However, if we change the “parameter” value to the name of another data column, we have a cross table for “sex” and the selected data column.
If we create a Metanode to contain also the Quickform node, the meta-node becomes a configurable node. In fact, by right-clicking the metanode and selecting configuring, we can define the value for the flow variable "parameter".
This makes even more sense if you run this workflow remotely on a KNIME Server. In this case, a window will prompt you for the meta-node/quickform parameter value. This allows you to replicate your meta-node/workflow and customize it on the fly by means of the Quick Form nodes.