Look at guvnor documentation for rest-api:
for binary:
http://{your-address}/drools-guvnor/rest/packages/{your-package}/assets/{your-process-id}/versions/{your-version}/binary
and for source:
http://{your-address}/drools-guvnor/rest/packages/{your-package}/assets/{your-process-id}/versions/{your-version}/source