LDN questions from the audience...

About reference implementations... The test suite automatically checks compliance, and most implementations are open source.

From people who are already considering to include LDN in their projects, asking for technical tips.

Authentication/login part... this isn't part of the protocol, orthogonal.

About LDP and Web of Things... can devices send notifications? What if applications can't use JSON-LD? Well, that's part of the Rec that applications must be able to at least do JSON-LD, but to cooperating applications can use content negotiation to agree on a more lightweight RDF format if they want. It's important for interoperability to be able to send JSON-LD in case a receiver can't understand any other RDF syntaxes; but if your sender and receiver both agree on another format (via the Accept-Post header) they can use that.

Do additions to the simple protocol make it complicated? What about spam? LDN recommends application-specific constraints to deal with issues like this. We don't have a blanket suggestion for how to deal with these kinds of problems in every domain though, we leave it to more focused experts.