feat: Customizing Cloudevents validation

Signed-off-by: vbhat6 <[email protected]>

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

@@ -0,0 +1,70 @@
+/*
+ * 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.provider;
+
+import io.cloudevents.CloudEvent;
+import io.cloudevents.core.validator.CloudEventValidator;
+
+import java.util.Iterator;
+import java.util.ServiceConfigurationError;
+import java.util.ServiceLoader;
+
+/**
+ * CloudEventValidatorProvider is a singleton class which loads and access CE Validator service providers on behalf of service clients.
+ */
+public class CloudEventValidatorProvider {
+
+    private static CloudEventValidatorProvider cloudEventValidatorProvider;
+
+    private ServiceLoader<CloudEventValidator> loader;
+
+    private CloudEventValidatorProvider(){
+        loader = ServiceLoader.load(CloudEventValidator.class);
+    }
+
+    public static synchronized CloudEventValidatorProvider getInstance(){
+        if(cloudEventValidatorProvider == null){
+            cloudEventValidatorProvider = new CloudEventValidatorProvider();
+        }
+        return cloudEventValidatorProvider;
+    }
+
+    /**
+     * iterates through available Cloudevent validators.
+     * @param cloudEvent
+     */
+    public void validate(CloudEvent cloudEvent){
+        try{
+            //
+            Iterator<CloudEventValidator> validatorIterator = loader.iterator();
+            while (validatorIterator.hasNext()){
+                CloudEventValidator validator = validatorIterator.next();
+                validator.validate(cloudEvent);
+
+            }
+        } catch (ServiceConfigurationError serviceError) {
+
+            serviceError.printStackTrace();
+        }
+
+    }
+
+
+
+
+
+}

core/src/main/java/io/cloudevents/core/v1/CloudEventBuilder.java

@@ -21,6 +21,7 @@
 import io.cloudevents.SpecVersion;
 import io.cloudevents.core.CloudEventUtils;
 import io.cloudevents.core.impl.BaseCloudEventBuilder;
+import io.cloudevents.core.provider.CloudEventValidatorProvider;
 import io.cloudevents.core.validator.CloudEventValidator;
 import io.cloudevents.rw.CloudEventContextReader;
 import io.cloudevents.rw.CloudEventContextWriter;
@@ -122,27 +123,8 @@ public CloudEvent build() {
 
         CloudEvent cloudEvent = new CloudEventV1(id, source, type, datacontenttype, dataschema, subject, time, this.data, this.extensions);
 
-        String name = null;
-        try{
-            // check if the header.validator.class is set as a system property,
-            if ((name = System.getProperty("header.validator.class")) != null){
-                Class<?> dynamicClass  = Class.forName(name);
-                Object dynamicObject = dynamicClass.newInstance();
-
-                if (dynamicObject instanceof CloudEventValidator) {
-                    // pluggable implementation of validation implementation
-                    CloudEventValidator cloudEventValidator = (CloudEventValidator) dynamicObject;
-
-                    cloudEventValidator.validate(cloudEvent);
-                }
-                else {
-                    throw new IllegalArgumentException("Passed class is not an instance of CloudEventValidator");
-                }
-            }
-        }
-        catch (ClassNotFoundException | InstantiationException | IllegalAccessException e) {
-            throw new IllegalArgumentException("Unable to load the header.validator.class passed as vm argument = " + name + ". Please check the classpath", e);
-        }
+        CloudEventValidatorProvider validator = CloudEventValidatorProvider.getInstance();
+        validator.validate(cloudEvent);
 
         return cloudEvent;
     }

core/src/main/java/io/cloudevents/core/validator/CloudEventValidator.java

@@ -1,8 +1,25 @@
+/*
+ * 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.validator;
 
 import io.cloudevents.CloudEvent;
 
 /**
+ * @author Vinay Bhat
  * Interface which defines validation for CloudEvents attributes and extensions.
  */
 public interface CloudEventValidator {

core/src/test/java/io/cloudevents/core/v1/CloudEventBuilderTest.java

@@ -142,48 +142,4 @@ void testMissingType() {
         ).hasMessageContaining("Attribute 'type' cannot be null");
     }
 
-    @Test
-    void testClassNotFoundExceptionForValidator(){
-
-        System.setProperty("header.validator.class", "io.cloudevents.core.v1.CustomCloudEventValidatorTest");
-            assertThatCode(() -> CloudEventBuilder
-            .v1()
-            .withId("000")
-            .withSource(URI.create("http://localhost"))
-            .withType("aaa")
-            .withExtension("astring", 10)
-            .build()
-        ).hasMessageContaining("Unable to load the header.validator.class passed as vm argument");
-    }
-
-    @Test
-    void testClassCastExceptionForValidator(){
-
-        System.setProperty("header.validator.class", "io.cloudevents.core.v1.CustomCloudEventValidator");
-        assertThatCode(() -> CloudEventBuilder
-            .v1()
-            .withId("000")
-            .withSource(URI.create("http://localhost"))
-            .withType("aaa")
-            .withExtension("astring", 10)
-            .build()
-        ).hasMessageContaining("Passed class is not an instance of CloudEventValidator");
-    }
-
-    /**
-     * This test is to check for the mandatory extension 'namespace' as per Organization need
-     */
-    @Test
-    void testMissingNamespaceExtension(){
-
-        System.setProperty("header.validator.class", "io.cloudevents.core.v1.CustomCloudEventValidatorImpl");
-        assertThatCode(() -> CloudEventBuilder
-            .v1()
-            .withId("000")
-            .withSource(URI.create("http://localhost"))
-            .withType("aaa")
-            .build()
-        ).hasMessageContaining("Extension 'namespace' cannot be null");
-    }
-
 }