DataSourceField Validation

Hi,
is there a way to get validation automatically working for datasourceFieldTypes?

I have created DS A with field b of type, which is pointing to dataSource B. In both dataSources I have validate operation. If I call validate on A, is it possible that framework will trigger validate operation also on datasource B?

Or do I need manually to create serverMethod for validate in ds A, which will trigger new validate request for ds B?

Regards
Matus