components/camel-avro/src/main/java/org/apache/camel/component/avro/AvroEndpoint.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * 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 org.apache.camel.component.avro;

import java.lang.reflect.Field;
import java.util.Collections;
import java.util.Map;

import org.apache.avro.Protocol;
import org.apache.avro.Schema;
import org.apache.avro.reflect.ReflectData;
import org.apache.camel.AsyncEndpoint;
import org.apache.camel.Component;
import org.apache.camel.Consumer;
import org.apache.camel.Exchange;
import org.apache.camel.ExchangePattern;
import org.apache.camel.Processor;
import org.apache.camel.spi.UriEndpoint;
import org.apache.camel.spi.UriParam;
import org.apache.camel.support.DefaultEndpoint;

/**
 * Working with Apache Avro for data serialization.
 */
@UriEndpoint(firstVersion = "2.10.0", scheme = "avro", title = "Avro", syntax = "avro:transport:host:port/messageName", label = "messaging,transformation")
public abstract class AvroEndpoint extends DefaultEndpoint implements AsyncEndpoint {

    @UriParam
    private AvroConfiguration configuration;

    public AvroEndpoint(String endpointUri, Component component, AvroConfiguration configuration) {
        super(endpointUri, component);
        this.configuration = configuration;
    }

    public Exchange createExchange(Protocol.Message message, Object request) {
        ExchangePattern pattern = ExchangePattern.InOut;
        if (message.getResponse().equals(Schema.Type.NULL)) {
            pattern = ExchangePattern.InOnly;
        }
        Exchange exchange = createExchange(pattern);
        exchange.getIn().setBody(request);
        exchange.getIn().setHeader(AvroConstants.AVRO_MESSAGE_NAME, message.getName());
        return exchange;
    }
    
    @Override
    public Consumer createConsumer(Processor processor) throws Exception {
        AvroConsumer consumer = new AvroConsumer(this, processor);
        configureConsumer(consumer);
        return consumer;
    }

    public AvroConfiguration getConfiguration() {
        return configuration;
    }

    @Override
    protected void doStart() throws Exception {
        super.doStart();

        validateConfiguration(configuration);

    }

    /**
     * Validates configuration
     */
    private void validateConfiguration(AvroConfiguration config) throws Exception {
        if (config.getProtocol() == null && config.getProtocolClassName() != null) {
            Class<?> protocolClass = getCamelContext().getClassResolver().resolveClass(config.getProtocolClassName());
            if (protocolClass != null) {
                try {
                    Field f = protocolClass.getField("PROTOCOL");
                    if (f != null) {
                        Protocol protocol = (Protocol)f.get(null);
                        config.setProtocol(protocol);
                    }
                } catch (NoSuchFieldException e) {
                    ReflectData reflectData = ReflectData.get();
                    config.setProtocol(reflectData.getProtocol(protocolClass));
                    config.setReflectionProtocol(true);
                }
            }
        }

        if (config.getProtocol() == null) {
            throw new IllegalArgumentException("Avro configuration does not contain protocol");
        }

        if (config.getMessageName() != null && !config.getProtocol().getMessages().containsKey(config.getMessageName())) {
            throw new IllegalArgumentException("Message " + config.getMessageName() + " is not defined in protocol");
        }

        if (config.isSingleParameter()) {
            Map<String, Protocol.Message> messageMap = config.getProtocol().getMessages();
            Iterable<Protocol.Message> messagesToCheck = config.getMessageName() == null
                    ? messageMap.values()
                    : Collections.singleton(messageMap.get(config.getMessageName()));
            for (Protocol.Message message : messagesToCheck) {
                if (message.getRequest().getFields().size() != 1) {
                    throw new IllegalArgumentException("Single parameter option can't be used with message "
                            + message.getName() + " because it has " + message.getRequest().getFields().size()
                            + " parameters defined"
                    );
                }
            }
        }
    }
}