feat: 70 implement dataref extension (#151)

Signed-off-by: Paul Schwarz <paulsschwarz@gmail.com>

core/src/main/java/io/cloudevents/core/extensions/DatarefExtension.java

@@ -0,0 +1,99 @@
+/*
+ * Copyright 2018-Present The CloudEvents Authors
+ * <p>
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package io.cloudevents.core.extensions;
+
+import io.cloudevents.CloudEventExtensions;
+import io.cloudevents.Extension;
+import io.cloudevents.core.extensions.impl.ExtensionUtils;
+import java.net.URI;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * This extension supports the "Claim Check Pattern". It allows to specify a reference to a location where the event payload is stored.
+ * @see <a href=https://github.com/cloudevents/spec/blob/v1.0/extensions/dataref.md>https://github.com/cloudevents/spec/blob/v1.0/extensions/dataref.md</a>
+ */
+public final class DatarefExtension implements Extension {
+
+    public static final String DATAREF = "dataref";
+    private static final Set<String> KEY_SET = Collections.unmodifiableSet(new HashSet<>(Collections.singletonList(DATAREF)));
+
+    private URI dataref;
+
+    public URI getDataref() {
+        return dataref;
+    }
+
+    public void setDataref(URI dataref) {
+        this.dataref = dataref;
+    }
+
+    @Override
+    public void readFrom(CloudEventExtensions extensions) {
+        Object value = extensions.getExtension(DATAREF);
+        if (value != null) {
+            this.dataref = URI.create(value.toString());
+        }
+    }
+
+    @Override
+    public Object getValue(String key) {
+        if (DATAREF.equals(key)) {
+            return this.dataref;
+        }
+        throw ExtensionUtils.generateInvalidKeyException(this.getClass().getSimpleName(), key);
+    }
+
+    @Override
+    public Set<String> getKeys() {
+        return KEY_SET;
+    }
+
+    @Override
+    public String toString() {
+        return "DatarefExtension{" +
+            "dataref='" + dataref + '\'' +
+            '}';
+    }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        return prime + ((dataref == null) ? 0 : dataref.hashCode());
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (obj == null) {
+            return false;
+        }
+        if (getClass() != obj.getClass()) {
+            return false;
+        }
+        DatarefExtension other = (DatarefExtension) obj;
+        if (dataref == null) {
+            return other.dataref == null;
+        } else {
+            return dataref.equals(other.dataref);
+        }
+    }
+}

core/src/main/java/io/cloudevents/core/provider/ExtensionProvider.java

@@ -19,6 +19,7 @@ package io.cloudevents.core.provider;
 
 import io.cloudevents.CloudEvent;
 import io.cloudevents.Extension;
+import io.cloudevents.core.extensions.DatarefExtension;
 import io.cloudevents.core.extensions.DistributedTracingExtension;
 
 import java.util.HashMap;
@@ -27,7 +28,7 @@ import java.util.function.Supplier;
 public final class ExtensionProvider {
 
     private static class SingletonContainer {
-        private final static ExtensionProvider INSTANCE = new ExtensionProvider();
+        private static final ExtensionProvider INSTANCE = new ExtensionProvider();
     }
 
     public static ExtensionProvider getInstance() {
@@ -40,6 +41,7 @@ public final class ExtensionProvider {
     private ExtensionProvider() {
         this.extensionFactories = new HashMap<>();
         registerExtension(DistributedTracingExtension.class, DistributedTracingExtension::new);
+        registerExtension(DatarefExtension.class, DatarefExtension::new);
     }
 
     public <T extends Extension> void registerExtension(Class<T> extensionClass, Supplier<Extension> factory) {

core/src/test/java/io/cloudevents/core/extensions/DatarefExtensionTest.java

@@ -0,0 +1,63 @@
+/*
+ * Copyright 2018-Present The CloudEvents Authors
+ * <p>
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+package io.cloudevents.core.extensions;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import io.cloudevents.CloudEvent;
+import io.cloudevents.core.builder.CloudEventBuilder;
+import io.cloudevents.core.provider.ExtensionProvider;
+import java.net.URI;
+import org.junit.jupiter.api.Test;
+
+/**
+ * @author paulschwarz
+ */
+public class DatarefExtensionTest {
+
+    @Test
+    public void writeExtension() {
+        DatarefExtension datarefExtension = new DatarefExtension();
+        datarefExtension.setDataref(URI.create("http://example"));
+
+        CloudEvent event = CloudEventBuilder.v1()
+            .withId("aaa")
+            .withSource(URI.create("http://localhost"))
+            .withType("example")
+            .withExtension(datarefExtension)
+            .build();
+
+        assertThat(event.getExtension(DatarefExtension.DATAREF))
+            .isEqualTo(URI.create("http://example"));
+    }
+
+    @Test
+    public void parseExtension() {
+        CloudEvent event = CloudEventBuilder.v1()
+            .withId("aaa")
+            .withSource(URI.create("http://localhost"))
+            .withType("example")
+            .withExtension(DatarefExtension.DATAREF, "http://example")
+            .build();
+
+        DatarefExtension datarefExtension = ExtensionProvider.getInstance()
+            .parseExtension(DatarefExtension.class, event);
+
+        assertThat(datarefExtension).isNotNull();
+        assertThat(datarefExtension.getDataref()).isEqualTo(URI.create("http://example"));
+    }
+}