Workflow inputs and outputs are key elements of the workflow. An input port is either a data input or an input parameter setting. In a Web form, this would be equivalent to text boxes and configuration settings. Output ports are the same. They allow you to retrieve the results of a service or/and the entire workflow.
Creating a New Workflow Input Port
By default the granularity of the input port is a Single value (the input port expects only one input value). For example if the workflow input port takes as values protein identifiers, in this case the workflow input value has to be just one protein identifier. However if the input values expect a list of values (e.g. list of protein identifier) you can specify the List depth.
Before Taverna invokes a workflow, it will check that all input and output values are syntactically correct (i.e. single values and lists).
Creating a New Workflow Output Port
Annotations on Workflow Inputs and Outputs
Descriptions and examples values can be added to workflow inputs and outputs to make them more understandable or sharable. The annotations section of the documentation explains how.