People think RDF is a pain because it is complicated. The truth is even worse. RDF is painfully simplistic, but it allows you to work with real-world data and problems that are horribly complicated. While you can avoid RDF, it is harder to avoid complicated data and complicated computer problems. RDF brings together data across application boundaries and imposes no discipline on mandatory or expected structures. This can make working with RDF data frustrating. Its schema and ontology languages can help define the meaning of RDF content but, again, can’t express rules about how actual data records should look. The contents of this book are nearly 20 years too late, but better now than never. Recent developments around RDF validation have finally made it easier to record, exchange, and understand rules about validating and otherwise checking RDF data. Who knows what wonders await us in another 20 years.
Dan Brickley, Schema.org and Google
Libby Miller, BBC