Interaction Models
When you interact with a given document on the Carbon server, you can specify a model that governs how the server behaves with respect to it. A document in Carbon can be treated as an LDP Container and an LDP RDF Source, or in some cases, an LDP Non-RDF Source (such as a binary file). When you want the server to treat a given document as one type or another, you can specify which model you prefer with an HTTP header in the client request.
The preferred interaction model is specified by the HTTP Prefer header, which must have one of the following values:
http://www.w3.org/ns/ldp#Container; rel=interaction-modelhttp://www.w3.org/ns/ldp#RDFSource; rel=interaction-modelhttp://www.w3.org/ns/ldp#NonRDFSource; rel=interaction-model
Container Behavior
When you want the server to treat a document as an LDP Container, use the following interaction model in your request:
Prefer http://www.w3.org/ns/ldp#Container; rel=interaction-model
As the name implies, LDP Containers contain things. Well, they don’t literally contain things in the same way that folders might, but the concept is similar. A container is itself an RDF Source with triples that link to a set of one or more members. So, when you want the server to behave in a way that helps you manage members in a collection, you’ll want to make requests that specify the LDP Container interaction model.
When a server is behaving with the Container interaction model, it can respond to client requests for creation, modification, and/or enumeration of its members.
A Container is also an LDP RDF Source, so while it has a special function as a membership controller, it may also represent additional data that is valuable to the clients that access it. In other words, in addition to having membership and/or containment triples, it can still have a variety of triples or properties that are specific to the resource it represents.
LDP RDF Source Behavior
When you want the server to treat a document as an LDP RDF Source, use the following interaction model in your request:
Prefer http://www.w3.org/ns/ldp#RDFSource; rel=interaction-model
An LDP RDF Source is an RDF graph or the source of one or more arbitrary triples that share the same subject URI. When we use the LDP RDF Source model for a document, we’re generally referring to the document as the resource it represents – some real world resource, for example. You typically prefer this model when your working only with the document itself, or properties of the document.
When a server is behaving with the RDF Source interaction model, it applies no special features for managing members or non-RDF “files”. Use the RDF Source model when you’re interested only in the document itself – reading the triples or properties it contains, updating or deleting them, and adding new ones. You can also use the model to create a document with a given URI that will not be contained by any given Container (i.e. to create an access point).
LDP NonRDF Source Behavior
An LDP Non-RDF Source is a resource whose state is not represented in RDF. For example, these can be binary or text documents that do not have useful RDF representations (i.e. “files”). When dealing with a Non-RDF Source, Carbon may still manage metadata about the resource using server-managed properties. You might also want to manage your own metadata about the resource, which you could do using the RDF Source interaction model on the same URI. But the context of the non-RDF interaction model is the non-RDF resource itself.
Prefer http://www.w3.org/ns/ldp#NonRDFSource; rel=interaction-model
When a server is behaving with the Non-RDF Source interaction model, it treats the given resource as a non-RDF “file”.