AM Semantic validation and correction of scientific workflows

Scientific workflows describe steps for orchestrating the execution of a network of computational operators toward some goal, such as data transformation for analysis or visualization. Typically, these operators consume and emit transformed data, or cause some effect. In most scientific workflow systems, the operators are typed to enable compatibility checks for their composition that make up a workflow. However, type checking performed by most such systems today is still largely confined to syntactic checking with limited, if any, semantic type checking support. In this paper, we present a type system incorporating the W3C OWL ontology language to aid in representing the semantics of data and workflow operators. We show how this type system supports the detection of type incompatibility errors in workflow compositions, and how it facilitates a (semi-)automatic type correction procedure using type transformations. We have incorporated our solution into Kepler, enabling users to statically test the type-consistency of workflows typed using our type language, and demonstrate that inconsistent bindings between expressively typed operators can be automatically corrected via a procedure that seeks to compose adapter/shim functions, such as unit transformations, time series interpolations, or some other arbitrarily complex data transformations.