There are various ways of creating Taverna workflows.
Taverna 2 workflows can be created using the web-based Taverna Online.
For Taverna 3.x we have developed a standalone workflow specification calledSCUFL2, this comes with a Java API which can be used as a set of freestanding JARs. This API can import .t2flow and allow inspection, creation, modification. This API exports to a new .wfbundle format which can be read by the Taverna 3 command line executor, but not (yet) by the Taverna 2 workbench.