Kopflos request pipeline

Incoming Request
  │
  └─▶ Kopflos handler
             │
   4**/5** ◀─┴─▶ Resource Shape Lookup
                   │
         4**/5** ◀─┴─▶ Resource Loader Lookup
                         │
               4**/5** ◀─┴─▶ Load Resource
                               │
                         4** ◀─┴─▶ Authorization
                                     │
                               400 ◀─┴─▶ Validation
                                           │
                                 4**/5** ◀─┴─▶ (User handler)
                                                 │
                                                 └─▶ Reply

Incoming request

Incoming request is handled by the server library, such as express or fastify and then forwarded to Kopflos.

Kopflos handler

Kopflos handler is the main entry point for all incoming requests. It is responsible for orchestrating the request pipeline.

Resource Shape Lookup

Resource Shape Lookup executes SPARQL against the default query endpoint to find the shape targeting the requested resource.

tip

See also: How to Select which resources should be served by the API

Resource Loader Lookup + Load Resource

When the Resource Shape is found, a resource loader is selected based from kopflos:resourceLoader property, going bottom-up from the Resource/Property Shape to the share kopflos:Config resource.

It is used to load the requested resource's Core Representation.

info

The Core Representation are the triples returned by the resource loader. Typically, that would be the result of a SPARQL DESCRIBE query or contents of resource's "own graph".

warning

By default, a loader which returns the resource's own graph is used.

Authorization

Not implemented yet.

Validation

Not implemented yet.

User handler

Finally, the handler is executed. If no handler is defined, and the request method is a GET, the resource's Core Representation is returned.

The result of the handler is forwarded back to the server library to be sent as a response.