feat: add SHACL processor

README.md

@@ -10,6 +10,15 @@ A proof-of-concept implementation of a Kotlin-based JVM runner. Currently, this
 
 This runner includes a set of standard processors that can be used directly by the end user without the need for additional dependencies. These processors also serve as a reference for processor developers. The implementation can be found [here](src/main/kotlin/std).
 
+##### RDF Utilities
+
+Interact with RDF data.
+
+| Processor                                                   | Description                    |
+|-------------------------------------------------------------|--------------------------------|
+| [`jvm:RDFValidator`](./src/main/kotlin/std/RDFValidator.kt) | Validate RDF data using SHACL. |
+
+
 ##### Network Utilities
 
 These processors interact with the network.
@@ -20,7 +29,7 @@ These processors interact with the network.
 
 ##### File Utilities
 
-These processors interact with the local file system.
+Fetch and write data from and to the local file system.
 
 | Processor                       | Description                                                            |
 |---------------------------------|------------------------------------------------------------------------|

src/main/kotlin/std/RDFValidator.kt

@@ -0,0 +1,75 @@
+package technology.idlab.std
+
+import bridge.Reader
+import bridge.Writer
+import java.io.ByteArrayOutputStream
+import java.io.File
+import org.apache.jena.graph.Graph
+import org.apache.jena.rdf.model.ModelFactory
+import org.apache.jena.shacl.ShaclValidator
+import technology.idlab.extensions.readModelRecursively
+import technology.idlab.logging.Log
+import technology.idlab.runner.Processor
+
+class RDFValidator(args: Map<String, Any>) : Processor(args) {
+  /** Default values. */
+  private val errorIsFatalDefault = false
+  private val printReportDefault = false
+
+  /** Arguments. */
+  private val errorIsFatal = this.getOptionalArgument<Boolean>("error_is_fatal")
+  private val printReport = this.getOptionalArgument<Boolean>("print_report")
+  private val input = this.getArgument<Reader>("input")
+  private val output = this.getArgument<Writer>("output")
+
+  /** Runtime fields. */
+  private val shapes: Graph
+  private val model = ModelFactory.createDefaultModel()
+  private val validator = ShaclValidator.get()
+
+  // Initialize the shape graph and validator.
+  init {
+    val path = this.getArgument<String>("shapes")
+    val file = File(path)
+    val shapesModel = file.readModelRecursively()
+    this.shapes = shapesModel.graph
+  }
+
+  /** Read incoming data, validate it, and output it. */
+  override fun exec() {
+    while (true) {
+      // Read incoming data.
+      val res = input.readSync()
+      if (res.isClosed()) {
+        break
+      }
+
+      // Parse as a model.
+      Log.shared.assert(model.isEmpty, "Model should be empty.")
+      model.read(res.value.toString())
+
+      // Validate the model.
+      val report = validator.validate(shapes, model.graph)
+      if (!report.conforms()) {
+        if (printReport.orElse(printReportDefault)) {
+          val out = ByteArrayOutputStream()
+          report.model.write(out, "TURTLE")
+          Log.shared.info(out.toString())
+        }
+
+        if (errorIsFatal.orElse(errorIsFatalDefault)) {
+          Log.shared.fatal("Validation error is fatal.")
+        }
+      }
+
+      // Reset model for next invocation.
+      model.removeAll(null, null, null)
+
+      // Propagate to the output.
+      output.pushSync(res.value)
+    }
+
+    // Close the output.
+    output.close()
+  }
+}

src/main/resources/std/rdf_validator.ttl

@@ -0,0 +1,44 @@
+@prefix jvm: <https://w3id.org/conn/jvm#>.
+@prefix owl: <http://www.w3.org/2002/07/owl#>.
+@prefix sh: <http://www.w3.org/ns/shacl#>.
+@prefix xsd: <http://www.w3.org/2001/XMLSchema#>.
+
+<> owl:imports <../pipeline.ttl>.
+
+jvm:RDFValidator a jvm:Processor;
+  jvm:file <../../kotlin/std/RDFValidator.kt>;
+  jvm:language "Kotlin".
+
+[] a sh:NodeShape;
+  sh:targetClass jvm:RDFValidator;
+  sh:property [
+    sh:path jvm:shapes;
+    sh:name "shapes";
+    sh:datatype xsd:string;
+    sh:minCount 1;
+    sh:maxCount 1;
+  ], [
+    sh:path jvm:error_is_fatal;
+    sh:name "error_is_fatal";
+    sh:datatype xsd:boolean;
+    sh:maxCount 1;
+  ], [
+    sh:path jvm:print_report;
+    sh:name "print_report";
+    sh:datatype xsd:boolean;
+    sh:maxCount 1;
+  ], [
+    sh:path jvm:input;
+    sh:name "input";
+    sh:class jvm:ChannelReader;
+    sh:minCount 1;
+    sh:maxCount 1;
+  ], [
+    sh:path jvm:output;
+    sh:name "output";
+    sh:class jvm:ChannelWriter;
+    sh:minCount 1;
+    sh:maxCount 1;
+  ];
+  sh:closed true;
+  sh:ignoredProperties (rdf:type).