SPARQL

Query: geroutet — FROM <feature?…> (the mediator picks the sources) instead of gepinnt — FROM <wfs?s=…> (one named source); an example without a routed form loads pinned either way; Basis-DLM / DLM50; Räumliche Relationen; Attributabfrage; Korrespondenz; Grenz-BBox; PREFIX gid: <gid/7.1#> SELECT ?s FROM <wfs?s=https%3A%2F%2Fgeoservices.bayern.de%2Fwfs%2Fv1%2Fogc_atkis_basisdlm.cgi&typenames=adv:AX_Wald&bbox=11.40,48.00,11.50,48.10> WHERE { ?s a gid:AX_Wald }; — SPARQL query link (copy for curl; the # in FROM IRIs becomes %23)

FROM — selecting the data

Every query needs at least one FROM (or FROM NAMED); the endpoint fetches those documents and queries over them. FROM/ FROM NAMED is restricted to the Linked AdV wrapper's two data routes — /oid, /wfs —, this mediator's routed /feature, and the wrapper's vocabulary documents (gid/7.1, ok/7.1/…, vocab/…); any other target is rejected with 400. The mediator and the wrapper share one public prefix, so relative IRIs resolve against that common root and the same query works on any deployment. FROM clauses are never rewritten — you name the exact source:

FROM <wfs?s={service}&typenames=adv:AX_Wald&bbox=W,S,E,N> — the pinned form: exactly one source, chosen by you (s=dlm50:{region} for one dump region), no routing. As FROM NAMED with GRAPH ?g you get to see which source answered which object (see the „Gepinnt“ examples). The same shape without bbox= is the attribute query within that one service (FROM <wfs?s={service}&typenames=adv:AX_Wasserlauf&eq=gewaesserkennzahl:276…>, also like=). Nothing rewrites a query for you.
FROM <feature?typenames=adv:AX_Wald&bbox=W,S,E,N> — the same shape on the mediator's /feature is the routed form: the mediator asks every source whose coverage meets the bbox (default: the Länder's Basis-DLM WFS plus the mounted DLM50 dumps; tier=dlm250 pins a model level) and composes one graph. Which sources answered is in the graph as dct:hasPart of the document, each part exactly a pinned /wfs?s=… URI; what is NOT in it is the source per object — for that use the pinned FROM NAMED form with GRAPH ?g. Every example below comes in both variants („gepinnt“ / „geroutet“); see routing.md in the mediator's repository.
FROM <oid/DEBYBDLMNP0006hi> — one object's document; FROM <gid/7.1> or FROM <ok/7.1/ax-vegetationsmerkmal-wald> add the schema or a code list to the query's graph

Several FROM clauses merge into one graph (see the sfCrosses example). A # inside a FROM IRI must be written %23.

Calling the endpoint

Request: GET sparql?query=…, a form POST with query=, or POST with Content-Type: application/sparql-query and the query as the body (SPARQL 1.1 Protocol §2.1). Any other POST body is 415. default-graph-uri/named-graph-uri may name the dataset instead of FROM (§2.1.4), under the same route rules.
Results: SELECT/ASK as SPARQL results JSON (default; .json), XML, TSV (.tsv) or CSV (.csv); CONSTRUCT/DESCRIBE as Turtle (default; .ttl), RDF/XML (.rdf) or N-Triples (.nt) — by suffix or Accept. An Accept naming only a form the query type lacks (a SELECT as Turtle) is 406, never a guess.
Budget: 60 s of execution per query (504 when exceeded); the graphs named in FROM are fetched from the wrapper and kept in memory for an hour (mediator shows the cache). Server-Timing on every answer splits load, parse and execution.
Machine-readable: a bare GET sparql with an RDF Accept is the service description.

GeoSPARQL functions

The endpoint registers the GeoSPARQL 1.1 function suite (OGC 22-047r1). Functions operate on geo:wktLiteral/geo:gmlLiteral values. Every RDF document served here lifts its GML geometry into the canonical form — bind it with ?s geo:hasGeometry/geo:asWKT ?g (PREFIX geo: <http://www.opengis.net/ont/geosparql#>); the raw GML stays untouched on locn:geometry as an rdf:XMLLiteral, which the functions do NOT accept. Common functions relevant to this dataset:

geof:metricArea(?g) — geodesic area in m²
geof:metricLength(?g) — geodesic length in m
geof:metricDistance(?a, ?b) — geodesic distance in m
geof:centroid(?g) — returns a geo:wktLiteral POINT

Topological relations (DE-9IM / Simple Features) return a boolean for a pair of geometries:

geof:sfEquals(?a, ?b) — topologically equal
geof:sfTouches(?a, ?b) — boundaries meet, interiors do not
geof:sfCrosses(?a, ?b) — interiors cross (e.g. a bridge line over a watercourse)
geof:sfIntersects(?a, ?b) — not disjoint
geof:sfContains(?a, ?b) — ?a contains ?b

Use PREFIX geof: <http://www.opengis.net/def/function/geosparql/>.

A non-standard helper returns a geometry's topological dimension as an integer (0 point, 1 curve, 2 surface):

fn:dimension(?g) — mirrors JTS getDimension(); test for curve/area with fn:dimension(?g) = 1 / = 2

Use PREFIX fn: <https://wunderfacts.com/adv/vocab/fn#>. These reproduce the ATKIS SK50 styling-rule predicates (mdl:geo_crosses → geof:sfCrosses, mdl:geo_isArea → fn:dimension(?g) = 2, etc.). See the example dropdown above for working queries.