When would the visits happen ? Just before normal validation ? Ram
On Wed, Nov 16, 2016 at 9:50 PM, Tushar Gosavi <tus...@apache.org> wrote: > Hi All, > > How about adding visitor like API for DAG in Apex, and an api to > register visitor for the DAG. > Possible use cases are > - Validator visitor which could validate the dag > - Visitor to inject properties/attribute in the operator/streams from > some external sources. > - Platform does not support validation of individual operators. > developer could write a validator visitor which would call validate > function of operator if it implements Validator interface. > - generate output schema based on operator config and input schema, > and set the schema on output stream. > > Sample API : > > dag.registerVisitor(DAGVisitor visitor); > > Call order of visitorFunctions. > - preVisitDAG(Attributes) // dag attributes > for all operators > - visitOperator(OperatorMeta meta) // access to operator, name, > attributes, properties > ports > - visitStream(StreamMeta meta) // access to > stream/name/attributes/properties/ports > - postVisitDAG() > > Regards, > -Tushar. >
