smolok.service.binding.ServiceBinding.groovy Maven / Gradle / Ivy

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/**
 * Licensed to the Rhiot under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The 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 smolok.service.binding

import com.fasterxml.jackson.databind.ObjectMapper;
import org.apache.camel.builder.RouteBuilder
import org.slf4j.Logger;
import org.slf4j.LoggerFactory

import static java.lang.String.format
import static smolok.lib.common.Reflections.isContainer
import static smolok.lib.common.Reflections.isPojo;

/**
 * Service binding is a general purpose backend service which can be used to bind communication coming through Event Bus
 * to the POJO service bean.
 */
class ServiceBinding extends RouteBuilder {

    // Static collaborators

    private static final Logger LOG = LoggerFactory.getLogger(ServiceBinding.class);

    // Constants

    private static final String TARGET_PROPERTY = "target";

    // Member collaborators

    protected final ServiceEventProcessor serviceEventProcessor

    // Member configuration

    protected final String serviceChannel

    // Constructors

    ServiceBinding(ServiceEventProcessor serviceEventProcessor, String serviceChannel) {
        this.serviceEventProcessor = serviceEventProcessor
        this.serviceChannel = serviceChannel
    }

    @Override
    public void configure() throws Exception {
        String fromChannel = format("amqp:%s.>?concurrentConsumers=20", serviceChannel);
        LOG.debug("Starting route consuming from channel: {}", fromChannel);

        from(fromChannel).process { exchange ->
            def message = exchange.in
            def channel = message.getHeader('JMSDestination', String.class)
            def operationBinding = serviceEventProcessor.process(new ServiceEvent(channel, message.body, message.headers))
            exchange.setProperty(TARGET_PROPERTY, "bean:" + operationBinding.service() + "?method=" + operationBinding.operation() + "&multiParameterArray=true");
            exchange.setProperty('BINDING', operationBinding)
            message.setBody(new Camels().convert(getContext(), operationBinding.arguments(), operationBinding.operationMethod().getParameterTypes()));
        }.toD(format('${property.%s}', TARGET_PROPERTY)).process { it ->
            def returnType = it.getProperty('BINDING', OperationBinding.class).operationMethod().returnType
            if (Void.TYPE == returnType) {
                it.getIn().setBody(null)
                // This is workaround needed due to the fact that Qpid JMS client doesn't support nested maps.
            } else if(isPojo(returnType) || isContainer(returnType)) {
                it.in.body = new ObjectMapper().writeValueAsBytes(it.in.body)
            }
        }
    }

}