1. A machine-readable storage medium storing one or more sequences of instructions comprising instructions for generating a graphical user interface, which instructions, when executed by one or more processors, cause: generating an expression pattern field, of the graphical user interface, that is configured to accept user input specifying a transformation expression pattern that specifies how to transform first input data into modified input data; generating parser sub-definition fields, of the graphical user interface, that are configured to accept user input specifying one or more parser sub-definitions, wherein for each parser sub-definition the parser sub-definition fields include: a first field configured to accept user input specifying a portion of the transformation expression pattern; a second field configured to accept user input specifying one of a plurality of object property types of an ontology of a data store; wherein each object property type, of the plurality of object property types, includes a data type of data that is associated with said each object property type; wherein each parser sub-definition, of the one or more parser sub-definitions, specifies how to transform a portion of the first input data into a portion of the modified input data that is to be stored in a component of one of the object property types.