There are many reading resources a few of which are mentioned bellow:

• G. Bakos. KNIME Essential, 2013.
• Davidson, Susan B., and Juliana Freire. Provenance and scientific workflows: challenges and opportunities. Proceedings of the 2008 ACM SIGMOD international conference on Management of data. ACM, 2008
• Ludäscher, Bertram, et al. Scientific workflow management and the Kepler system. Concurrency and Computation: Practice and Experience 18.10 (2006): 1039-1065
• Sonntag, Mirko, Dimka Karastoyanova, and Ewa Deelman. Bridging the gap between business and scientific workflows: humans in the loop of scientific workflows. e-Science (e-Science), 2010 IEEE Sixth International Conference on. IEEE, 2010.

Whether you want to write your own plugin or extend our OSA plugin, there are some basics you need to learn including:

• KNIME new node wizard
• Testing your new node
• Workflow creation with KNIME
• Packaging your new plugin

You may also contribute to OSA development or report bugs/issues by reviewing the source code on Github.