Reimplement mapping scripts (step-01, step-02) in Rust.

step-01 performs W3C Direct Mapping from MariaDB to Turtle using sophia.
step-02 applies SPARQL UPDATE queries using oxigraph.

Cargo.toml

@@ -0,0 +1,18 @@
+[package]
+name = "mapping"
+version = "0.1.0"
+edition = "2021"
+
+[[bin]]
+name = "step-01"
+path = "src/map/step_01.rs"
+
+[[bin]]
+name = "step-02"
+path = "src/map/step_02.rs"
+
+[dependencies]
+sophia = "0.9"
+oxigraph = "*"
+mysql = "*"
+urlencoding = "*"

README.md

@@ -2,6 +2,36 @@
 
 To generate a knowledge graph about migrants in the theatre in Europe.
 
+## Running the scripts
+
+The mapping scripts have been reimplemented in Rust for faster execution. Both
+scripts must be run from this directory (`mapping/`).
+
+**Prerequisites:** Start the MariaDB container before running step 1:
+
+```sh
+docker compose up -d
+```
+
+**Step 1** — Direct Mapping from MariaDB to RDF (`data/graph-01.ttl`):
+
+```sh
+cargo run --release --bin step-01
+```
+
+**Step 2** — Apply SPARQL UPDATE queries (`data/graph-02.ttl`):
+
+```sh
+cargo run --release --bin step-02
+```
+
+Alternatively, after installing with `cargo install --path .`:
+
+```sh
+step-01
+step-02
+```
+
 ## Generating the ontology
 
 Next there are set of steps describing how to generate the migrants RDF graph.

src/map/step_01.rs

@@ -0,0 +1,233 @@
+/// Step 1: Direct Mapping from relational database to RDF.
+///
+/// Connects to MariaDB and produces `data/graph-01.ttl` following the
+/// W3C Direct Mapping specification.
+///
+/// Usage: Run from the mapping project directory:
+///   cargo run --release --bin step-01
+
+use std::collections::HashMap;
+use std::fs;
+use std::io::BufWriter;
+
+use mysql::prelude::*;
+use mysql::*;
+use sophia::api::ns::{rdf, xsd};
+use sophia::api::prelude::*;
+use sophia::api::prefix::{Prefix, PrefixMapPair};
+use sophia::api::term::SimpleTerm;
+use sophia::turtle::serializer::turtle::{TurtleConfig, TurtleSerializer};
+
+type MyGraph = Vec<[SimpleTerm<'static>; 3]>;
+
+const BASE_IRI: &str = "http://example.org/migrants/";
+
+/// Primary keys for each table.
+const PRIMARY_KEYS: &[(&str, &str)] = &[
+    ("location", "IDLocation"),
+    ("migration_table", "IDMig"),
+    ("organisation", "IDOrganisation"),
+    ("person", "IDPerson"),
+    ("person_profession", "IDProfPerson"),
+    ("personnames", "IDPersonname"),
+    ("relationship", "IDRel"),
+    ("religions", "IDReligion"),
+    ("work", "IDWork"),
+];
+
+/// Foreign key definitions: (table, column, referenced_table).
+const FOREIGN_KEYS: &[(&str, &str, &str)] = &[
+    ("migration_table", "IDPerson", "person"),
+    ("migration_table", "IDStartPlace", "location"),
+    ("migration_table", "IDDestPlace", "location"),
+    ("organisation", "IDLocation", "location"),
+    ("person", "IDBirthPlace", "location"),
+    ("person", "IDDeathPlace", "location"),
+    ("personnames", "IDPerson", "person"),
+    ("person_profession", "IDPerson", "person"),
+    ("relationship", "IDPerson_active", "person"),
+    ("relationship", "IDPerson_passive", "person"),
+    ("relationship", "IDLocation", "location"),
+    ("relationship", "IDOrganisation", "organisation"),
+    ("religions", "IDPerson", "person"),
+    ("work", "IDPerson", "person"),
+    ("work", "IDLocation", "location"),
+    ("work", "IDOrganisation", "organisation"),
+    ("work", "IDOrganisation2", "organisation"),
+];
+
+fn build_fk_map() -> HashMap<(&'static str, &'static str), &'static str> {
+    let mut map = HashMap::new();
+    for &(table, col, ref_table) in FOREIGN_KEYS {
+        map.insert((table, col), ref_table);
+    }
+    map
+}
+
+fn row_iri(table: &str, pk_value: &str) -> SimpleTerm<'static> {
+    let encoded = urlencoding::encode(pk_value);
+    SimpleTerm::Iri(
+        sophia::api::term::IriRef::new_unchecked(
+            format!("{}{}/{}", BASE_IRI, table, encoded).into(),
+        ),
+    )
+}
+
+fn class_iri(table: &str) -> SimpleTerm<'static> {
+    SimpleTerm::Iri(
+        sophia::api::term::IriRef::new_unchecked(format!("{}{}", BASE_IRI, table).into()),
+    )
+}
+
+fn column_iri(table: &str, column: &str) -> SimpleTerm<'static> {
+    SimpleTerm::Iri(
+        sophia::api::term::IriRef::new_unchecked(
+            format!("{}{}#{}", BASE_IRI, table, column).into(),
+        ),
+    )
+}
+
+fn ref_iri(table: &str, fk_col: &str) -> SimpleTerm<'static> {
+    SimpleTerm::Iri(
+        sophia::api::term::IriRef::new_unchecked(
+            format!("{}{}#ref-{}", BASE_IRI, table, fk_col).into(),
+        ),
+    )
+}
+
+fn rdf_type_term() -> SimpleTerm<'static> {
+    SimpleTerm::Iri(sophia::api::term::IriRef::new_unchecked(
+        rdf::type_.iri().unwrap().as_str().to_string().into(),
+    ))
+}
+
+fn to_rdf_literal(value: &Value) -> Option<SimpleTerm<'static>> {
+    match value {
+        Value::NULL => None,
+        Value::Int(i) => Some(SimpleTerm::LiteralDatatype(
+            i.to_string().into(),
+            sophia::api::term::IriRef::new_unchecked(
+                xsd::integer.iri().unwrap().as_str().to_string().into(),
+            ),
+        )),
+        Value::UInt(u) => Some(SimpleTerm::LiteralDatatype(
+            u.to_string().into(),
+            sophia::api::term::IriRef::new_unchecked(
+                xsd::integer.iri().unwrap().as_str().to_string().into(),
+            ),
+        )),
+        Value::Float(f) => Some(SimpleTerm::LiteralDatatype(
+            f.to_string().into(),
+            sophia::api::term::IriRef::new_unchecked(
+                xsd::double.iri().unwrap().as_str().to_string().into(),
+            ),
+        )),
+        Value::Double(d) => Some(SimpleTerm::LiteralDatatype(
+            d.to_string().into(),
+            sophia::api::term::IriRef::new_unchecked(
+                xsd::double.iri().unwrap().as_str().to_string().into(),
+            ),
+        )),
+        Value::Date(year, month, day, _, _, _, _) => Some(SimpleTerm::LiteralDatatype(
+            format!("{:04}-{:02}-{:02}", year, month, day).into(),
+            sophia::api::term::IriRef::new_unchecked(
+                xsd::date.iri().unwrap().as_str().to_string().into(),
+            ),
+        )),
+        Value::Bytes(b) => {
+            let s = String::from_utf8_lossy(b).into_owned();
+            Some(SimpleTerm::LiteralDatatype(
+                s.into(),
+                sophia::api::term::IriRef::new_unchecked(
+                    xsd::string.iri().unwrap().as_str().to_string().into(),
+                ),
+            ))
+        }
+        _ => {
+            // Treat everything else as a plain string literal
+            let s: String = from_value(value.clone());
+            Some(SimpleTerm::LiteralDatatype(
+                s.into(),
+                sophia::api::term::IriRef::new_unchecked(
+                    xsd::string.iri().unwrap().as_str().to_string().into(),
+                ),
+            ))
+        }
+    }
+}
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let fk_map = build_fk_map();
+
+    let url = "mysql://migrants:1234@127.0.0.1:3306/migrants";
+    let pool = Pool::new(url)?;
+    let mut conn = pool.get_conn()?;
+
+    let mut graph = MyGraph::new();
+    let rdf_type = rdf_type_term();
+
+    for &(table, pk_col) in PRIMARY_KEYS {
+        let query = format!("SELECT * FROM `{}`", table);
+        let rows: Vec<Row> = conn.query(query)?;
+
+        for row in &rows {
+            let pk_value: String = row
+                .get::<Value, _>(pk_col)
+                .map(|v| from_value::<String>(v))
+                .unwrap_or_default();
+            let subject = row_iri(table, &pk_value);
+
+            // rdf:type
+            graph.push([subject.clone(), rdf_type.clone(), class_iri(table)]);
+
+            let columns = row.columns_ref();
+            for (i, col_def) in columns.iter().enumerate() {
+                let col_name = col_def.name_str().to_string();
+                let value: Value = row.get::<Value, _>(i).unwrap_or(Value::NULL);
+
+                if value == Value::NULL {
+                    continue;
+                }
+
+                if let Some(&ref_table) = fk_map.get(&(table, col_name.as_str())) {
+                    // Foreign key -> object property
+                    let fk_value: String = from_value(value);
+                    graph.push([
+                        subject.clone(),
+                        ref_iri(table, &col_name),
+                        row_iri(ref_table, &fk_value),
+                    ]);
+                } else {
+                    // Regular column -> datatype property
+                    if let Some(literal) = to_rdf_literal(&value) {
+                        graph.push([subject.clone(), column_iri(table, &col_name), literal]);
+                    }
+                }
+            }
+        }
+    }
+
+    let output_path = "data/graph-01.ttl";
+    fs::create_dir_all("data")?;
+    let file = fs::File::create(output_path)?;
+    let writer = BufWriter::new(file);
+
+    let mut prefix_map: Vec<PrefixMapPair> = TurtleConfig::default_prefix_map();
+    prefix_map.push((
+        Prefix::new_unchecked("rdf".into()),
+        Iri::new_unchecked("http://www.w3.org/1999/02/22-rdf-syntax-ns#".into()),
+    ));
+    prefix_map.push((
+        Prefix::new_unchecked("xsd".into()),
+        Iri::new_unchecked("http://www.w3.org/2001/XMLSchema#".into()),
+    ));
+    let config = TurtleConfig::new().with_own_prefix_map(prefix_map);
+
+    let mut serializer = TurtleSerializer::new_with_config(writer, config);
+    serializer.serialize_graph(&graph)?;
+
+    let count = graph.len();
+    eprintln!("Written {} triples to {}", count, output_path);
+
+    Ok(())
+}

src/map/step_02.rs

@@ -0,0 +1,84 @@
+/// Step 2: Apply SPARQL UPDATE queries to transform the RDF graph.
+///
+/// Loads `data/graph-01.ttl`, applies all SPARQL UPDATE queries from the
+/// `updates/` directory (sorted alphabetically), and writes the result
+/// to `data/graph-02.ttl`.
+///
+/// Usage: Run from the mapping project directory:
+///   cargo run --release --bin step-02
+
+use std::fs;
+
+use oxigraph::io::{RdfFormat, RdfParser};
+use oxigraph::model::GraphNameRef;
+use oxigraph::store::Store;
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let input_path = "data/graph-01.ttl";
+    let output_path = "data/graph-02.ttl";
+    let updates_dir = "updates";
+
+    // Create in-memory store and load input graph
+    let store = Store::new()?;
+
+    eprintln!("Loading graph from {}...", input_path);
+    let input = fs::File::open(input_path)?;
+    let reader = std::io::BufReader::new(input);
+    let parser = RdfParser::from_format(RdfFormat::Turtle)
+        .without_named_graphs()
+        .with_default_graph(GraphNameRef::DefaultGraph);
+    store.load_from_reader(parser, reader)?;
+
+    let initial_count = count_triples(&store);
+    eprintln!("Loaded {} triples.", initial_count);
+
+    // Read and sort SPARQL UPDATE files
+    let mut update_files: Vec<_> = fs::read_dir(updates_dir)?
+        .filter_map(|e| e.ok())
+        .map(|e| e.path())
+        .filter(|p| {
+            p.extension()
+                .and_then(|e| e.to_str())
+                .map_or(false, |e| e == "rq")
+        })
+        .collect();
+    update_files.sort();
+
+    // Apply each SPARQL UPDATE query
+    for query_file in &update_files {
+        let query = fs::read_to_string(query_file)?;
+        let name = query_file
+            .file_name()
+            .and_then(|n| n.to_str())
+            .unwrap_or("unknown");
+
+        let before = count_triples(&store);
+        store.update(&query)?;
+        let after = count_triples(&store);
+
+        let diff = after as i64 - before as i64;
+        let sign = if diff >= 0 { "+" } else { "" };
+        eprintln!(
+            "Applied {}: {} -> {} triples ({}{})",
+            name, before, after, sign, diff
+        );
+    }
+
+    let final_count = count_triples(&store);
+    eprintln!("Writing {} triples to {}...", final_count, output_path);
+
+    // Dump store to Turtle
+    fs::create_dir_all("data")?;
+    let output = fs::File::create(output_path)?;
+    let writer = std::io::BufWriter::new(output);
+    store.dump_graph_to_writer(GraphNameRef::DefaultGraph, RdfFormat::Turtle, writer)?;
+
+    eprintln!("Done.");
+    Ok(())
+}
+
+fn count_triples(store: &Store) -> usize {
+    store
+        .quads_for_pattern(None, None, None, None)
+        .count()
+}