(enhance) introduce resolving strategy (configurable xml security); introduce API configuration

src/main/java/de/kosit/validationtool/api/ResolvingConfigurationStrategy.java

@@ -0,0 +1,64 @@
+package de.kosit.validationtool.api;
+
+import java.net.URI;
+
+import javax.xml.transform.URIResolver;
+import javax.xml.validation.Schema;
+import javax.xml.validation.SchemaFactory;
+import javax.xml.validation.Validator;
+
+import net.sf.saxon.s9api.Processor;
+
+/**
+ * Centralized construction and configuration of XML related infrastructore components. The KoSIT Validator provides out
+ * of the box implementaions with various security levels.
+ * 
+ * If you decide to implement a custom strategy, please be aware of XML security within your stack. The validator
+ * components beyond this strategy asume secured implementation of the interfaces provided by this strategy. There is no
+ * effort to mitigate or prevent xml related security issues such as XXE, loading external sources etc.
+ * 
+ * @see de.kosit.validationtool.impl.ResolvingMode
+ * @author Andreas Penski
+ */
+public interface ResolvingConfigurationStrategy {
+
+    /**
+     * Creates a preconfigured {@link SchemaFactory} for loading {@link javax.xml.validation.Schema} objects. The
+     * implementation is responsible for xml security. Take care
+     * 
+     * @return preconfigured {@link SchemaFactory}
+     */
+    SchemaFactory createSchemaFactory();
+
+    /**
+     * Creates a preconfigured {@link Processor Saxon Processor} for various tasks within the Validator. The validator
+     * leverages the saxon s9api for internal processing e.g. xml reading and writing. So this is the main object to secure
+     * for reading, transforming and writing xml files.
+     * 
+     * @return a preconfigured {@link Processor}
+     */
+    Processor createProcessor();
+
+    /**
+     * Creates a specific implementation for resolving referenced objects in XML files. The URIResolver, it is used for
+     * dereferencing an absolute URI (after resolution) to return a {@link javax.xml.transform.Source}. It <b>can</b> be
+     * used for resolving relative URIs against a base URI or restrict access to certain URIs.
+     * <p>
+     * This URIResolver is used to dereference the URIs appearing in <code>xsl:import</code>, <code>xsl:include</code>, and
+     * <code>xsl:import-schema</code> declarations.
+     * </p>
+     * 
+     * @return a preconfigured {@link URIResolver}
+     */
+    URIResolver createResolver(URI scenarioRepository);
+
+    /**
+     * Creates a preconfigured {@link Validator } instance for a given schema for xml file validation. The implementation
+     * takes care about security and reference resolving strategies.
+     * 
+     * @param schema the scheme to create a {@link Validator} for
+     * @return a preconfigured {@link Validator}
+     */
+    Validator createValidator(Schema schema);
+
+}