feat: add basic support for XML schema format in messages for v3.0.0 spec

asyncapi-core/src/main/java/com/asyncapi/schemas/asyncapi/multiformat/MultiFormatSchema.java

@@ -97,6 +97,9 @@
                 "application/vnd.apache.avro;version=1.11.1",
                 "application/vnd.apache.avro+json;version=1.11.1",
                 "application/vnd.apache.avro+yaml;version=1.11.1"
+        }),
+        @JsonSubTypes.Type(value = XMLFormatSchema.class, names = {
+                "application/xml"
         })
 })
 @EqualsAndHashCode(callSuper = true)

asyncapi-core/src/main/java/com/asyncapi/schemas/asyncapi/multiformat/XMLFormatSchema.java

@@ -0,0 +1,66 @@
+package com.asyncapi.schemas.asyncapi.multiformat;
+
+import com.asyncapi.schemas.asyncapi.AsyncAPISchema;
+import com.asyncapi.schemas.asyncapi.Reference;
+import com.asyncapi.schemas.xml.XMLSchemaDeserializer;
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonProperty;
+import com.fasterxml.jackson.databind.annotation.JsonDeserialize;
+import lombok.EqualsAndHashCode;
+import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
+
+/**
+ * The XML Format Schema Object represents a schema definition. It differs from the {@link AsyncAPISchema} in that it supports
+ * multiple schema formats or languages (e.g., JSON Schema, Avro, XML, etc.).
+ *
+ * @see <a href="https://www.asyncapi.com/docs/reference/specification/v3.0.0#multiFormatSchemaObject">Multi Format Schema</a>
+ * @see <a href="https://www.asyncapi.com/docs/reference/specification/v3.0.0#schemaObject">Schema</a>
+ */
+@EqualsAndHashCode(callSuper = true)
+public class XMLFormatSchema extends MultiFormatSchema<Object> {
+
+    public XMLFormatSchema(@NotNull @JsonDeserialize(using = XMLSchemaDeserializer.class) Object schema) {
+        super("application/xml", schema);
+    }
+
+    @JsonCreator(mode = JsonCreator.Mode.PROPERTIES)
+    public XMLFormatSchema(
+            @JsonProperty("schemaFormat") @Nullable String schemaFormat,
+            @JsonProperty("schema") @NotNull @JsonDeserialize(using = XMLSchemaDeserializer.class) Object schema
+    ) {
+        super(schemaFormat(schemaFormat), schema);
+    }
+
+    /**
+     * Schema <b>MUST</b> be one of:
+     * <ul>
+     *     <li>{@link Reference}</li>
+     * </ul>
+     *
+     * @param schema XML Schema or Reference
+     */
+    @Override
+    public void setSchema(@NotNull Object schema) {
+        super.setSchema(schema);
+    }
+
+    /**
+     * Schema:
+     * <ul>
+     *     <li>{@link Reference}</li>
+     * </ul>
+     */
+    @NotNull
+    public Object getSchema() {
+        return super.getSchema();
+    }
+
+    @NotNull
+    private static String schemaFormat(@Nullable String schemaFormat) {
+        if (schemaFormat == null || schemaFormat.isEmpty()) {
+            return "application/xml";
+        }
+        return schemaFormat;
+    }
+}

asyncapi-core/src/main/java/com/asyncapi/schemas/xml/XMLSchemaDeserializer.java

@@ -0,0 +1,48 @@
+package com.asyncapi.schemas.xml;
+
+import com.asyncapi.schemas.asyncapi.Reference;
+import com.fasterxml.jackson.core.JsonParser;
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.core.ObjectCodec;
+import com.fasterxml.jackson.databind.DeserializationContext;
+import com.fasterxml.jackson.databind.JsonDeserializer;
+import com.fasterxml.jackson.databind.JsonNode;
+import com.fasterxml.jackson.databind.node.JsonNodeType;
+
+import java.io.IOException;
+import java.util.Objects;
+
+public class XMLSchemaDeserializer extends JsonDeserializer<Object> {
+
+    @Override
+    public Object deserialize(JsonParser p, DeserializationContext ctxt) throws IOException, JsonProcessingException {
+        ObjectCodec objectCodec = p.getCodec();
+        JsonNode node = objectCodec.readTree(p);
+
+        return chooseKnownPojo(node, objectCodec);
+    }
+
+    private Object chooseKnownPojo(JsonNode jsonNode, final ObjectCodec objectCodec) throws IOException {
+        try (JsonParser jsonParser = jsonNode.traverse(objectCodec)) {
+            JsonNodeType nodeType = jsonNode.getNodeType();
+
+            if (Objects.requireNonNull(nodeType) == JsonNodeType.STRING) {
+                return jsonParser.readValueAs(String.class);
+            }
+
+            if(Objects.requireNonNull(nodeType) == JsonNodeType.OBJECT) {
+                if (isRefNode(jsonNode)) {
+                    return jsonParser.readValueAs(Reference.class);
+                }
+                return null;
+            }
+
+            return null;
+        }
+    }
+
+    private boolean isRefNode(JsonNode jsonNode) {
+        return jsonNode.size() == 1 && jsonNode.has("$ref");
+    }
+
+}

asyncapi-core/src/test/kotlin/com/asyncapi/schemas/multiformat/xml/XmlFormatSchemaTest.kt

@@ -0,0 +1,56 @@
+package com.asyncapi.schemas.multiformat.xml
+
+import com.asyncapi.schemas.asyncapi.Reference
+import com.asyncapi.schemas.asyncapi.multiformat.XMLFormatSchema
+import com.asyncapi.v3.ClasspathUtils
+import com.asyncapi.v3._0_0.model.AsyncAPI
+import com.asyncapi.v3._0_0.model.channel.message.Message
+import com.fasterxml.jackson.annotation.JsonInclude
+import com.fasterxml.jackson.databind.ObjectMapper
+import com.fasterxml.jackson.dataformat.yaml.YAMLFactory
+import org.junit.jupiter.api.Test
+
+class XmlFormatSchemaTest {
+
+    private val objectMapper = ObjectMapper(YAMLFactory())
+        .setSerializationInclusion(JsonInclude.Include.NON_NULL)
+
+    @Test
+    fun `should parse a spec where the schemaFormat is application xml and the schema is referenced from an external xml schema file`() {
+        val specFilePath = "/examples/v3.0.0/xml/simple-referenced-schema.yaml"
+        val asyncAPI = parse(specFilePath)
+
+        val payload = (asyncAPI?.components?.messages?.get("UserSignedUp") as? Message)?.payload
+
+        assert(payload is XMLFormatSchema)
+        payload as XMLFormatSchema
+
+        assert(payload.schemaFormat == "application/xml")
+        assert(payload.schema is Reference)
+
+        assert((payload.schema as Reference).ref == "/path/to/schema.xml")
+    }
+
+    @Test
+    fun `should parse a spec where the schemaFormat is application xml and the schema is specified as an inline string`() {
+        val specFilePath = "/examples/v3.0.0/xml/simple-string-schema.yaml"
+        val asyncAPI = parse(specFilePath)
+
+        val payload = (asyncAPI?.components?.messages?.get("UserSignedUp") as? Message)?.payload
+
+        assert(payload is XMLFormatSchema)
+        payload as XMLFormatSchema
+
+        assert(payload.schemaFormat == "application/xml")
+        assert(payload.schema is String)
+
+        assert((payload.schema as String).contains("<xs:schema"))
+    }
+
+    private fun parse(specPath: String): AsyncAPI? {
+        return objectMapper.readValue(
+            ClasspathUtils.readAsString(specPath),
+            AsyncAPI::class.java
+        )
+    }
+}

asyncapi-core/src/test/resources/examples/v3.0.0/xml/simple-referenced-schema.yaml

@@ -0,0 +1,25 @@
+asyncapi: 3.0.0
+info:
+  title: Account Service
+  version: 1.0.0
+  description: This service is in charge of processing user signups
+channels:
+  userSignedup:
+    address: user/signedup
+    messages:
+      UserSignedUp:
+        $ref: '#/components/messages/UserSignedUp'
+operations:
+  sendUserSignedup:
+    action: send
+    channel:
+      $ref: '#/channels/userSignedup'
+    messages:
+      - $ref: '#/channels/userSignedup/messages/UserSignedUp'
+components:
+  messages:
+    UserSignedUp:
+      payload:
+        schemaFormat: application/xml
+        schema:
+          $ref: /path/to/schema.xml

asyncapi-core/src/test/resources/examples/v3.0.0/xml/simple-string-schema.yaml

@@ -0,0 +1,44 @@
+asyncapi: 3.0.0
+info:
+  title: Account Service
+  version: 1.0.0
+  description: This service is in charge of processing user signups
+channels:
+  userSignedup:
+    address: user/signedup
+    messages:
+      UserSignedUp:
+        $ref: '#/components/messages/UserSignedUp'
+operations:
+  sendUserSignedup:
+    action: send
+    channel:
+      $ref: '#/channels/userSignedup'
+    messages:
+      - $ref: '#/channels/userSignedup/messages/UserSignedUp'
+components:
+  messages:
+    UserSignedUp:
+      payload:
+        schemaFormat: application/xml
+        schema: |
+          <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" elementFormDefault="qualified">
+            <xs:element name="User">
+              <xs:complexType>
+                <xs:sequence>
+                  <xs:element name="displayName" type="xs:string">
+                      <xs:annotation>
+                        <xs:documentation>Name of the user</xs:documentation>
+                      </xs:annotation>
+                  </xs:element>
+                  <xs:element name="email" type="xs:string">
+                      <xs:annotation>
+                        <xs:documentation>Email of the user</xs:documentation>
+                      </xs:annotation>
+                  </xs:element>
+                </xs:sequence>
+              </xs:complexType>
+            </xs:element>
+          </xs:schema>
+
+