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The Core Camel Java DSL based router
/**
* 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.impl.cloud;
import java.util.Map;
import org.apache.camel.AsyncCallback;
import org.apache.camel.AsyncProcessor;
import org.apache.camel.CamelContext;
import org.apache.camel.Exchange;
import org.apache.camel.ExchangePattern;
import org.apache.camel.Expression;
import org.apache.camel.Message;
import org.apache.camel.cloud.ServiceDefinition;
import org.apache.camel.cloud.ServiceLoadBalancer;
import org.apache.camel.language.simple.SimpleLanguage;
import org.apache.camel.processor.SendDynamicProcessor;
import org.apache.camel.support.ServiceSupport;
import org.apache.camel.util.AsyncProcessorHelper;
import org.apache.camel.util.ObjectHelper;
import org.apache.camel.util.ServiceHelper;
import org.apache.camel.util.StringHelper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class DefaultServiceCallProcessor extends ServiceSupport implements AsyncProcessor {
private static final Logger LOGGER = LoggerFactory.getLogger(DefaultServiceCallProcessor.class);
private final ExchangePattern exchangePattern;
private final String name;
private final String scheme;
private final String uri;
private final String contextPath;
private final CamelContext camelContext;
private final ServiceLoadBalancer loadBalancer;
private final Expression expression;
private SendDynamicProcessor processor;
public DefaultServiceCallProcessor(
CamelContext camelContext, String name, String scheme, String uri, ExchangePattern exchangePattern,
ServiceLoadBalancer loadBalancer, Expression expression) {
this.uri = uri;
this.exchangePattern = exchangePattern;
this.camelContext = camelContext;
this.loadBalancer = loadBalancer;
// setup from the provided name which can contain scheme and context-path information as well
String serviceName;
if (name.contains("/")) {
serviceName = StringHelper.before(name, "/");
this.contextPath = StringHelper.after(name, "/");
} else if (name.contains("?")) {
serviceName = StringHelper.before(name, "?");
this.contextPath = StringHelper.after(name, "?");
} else {
serviceName = name;
this.contextPath = null;
}
if (serviceName.contains(":")) {
this.scheme = StringHelper.before(serviceName, ":");
this.name = StringHelper.after(serviceName, ":");
} else {
this.scheme = scheme;
this.name = serviceName;
}
this.expression = expression;
}
// *************************************
// Properties
// *************************************
public ExchangePattern getExchangePattern() {
return exchangePattern;
}
public String getName() {
return name;
}
public String getScheme() {
return scheme;
}
public String getUri() {
return uri;
}
public String getContextPath() {
return contextPath;
}
public ServiceLoadBalancer getLoadBalancer() {
return loadBalancer;
}
public Expression getExpression() {
return expression;
}
// *************************************
// Lifecycle
// *************************************
@Override
protected void doStart() throws Exception {
StringHelper.notEmpty(name, "name", "service name");
ObjectHelper.notNull(camelContext, "camel context");
ObjectHelper.notNull(expression, "expression");
ObjectHelper.notNull(loadBalancer, "load balancer");
processor = new SendDynamicProcessor(uri, expression);
processor.setCamelContext(camelContext);
if (exchangePattern != null) {
processor.setPattern(exchangePattern);
}
// Start services if needed
ServiceHelper.startService(processor);
ServiceHelper.startService(loadBalancer);
}
@Override
protected void doStop() throws Exception {
// Stop services if needed
ServiceHelper.stopService(loadBalancer);
ServiceHelper.stopService(processor);
}
// *************************************
// Processor
// *************************************
@Override
public void process(Exchange exchange) throws Exception {
AsyncProcessorHelper.process(this, exchange);
}
@Override
public boolean process(final Exchange exchange, final AsyncCallback callback) {
final Message message = exchange.getIn();
// the values can be dynamic using simple language so compute those
final String serviceName = applySimpleLanguage(name, exchange);
final String serviceUri = applySimpleLanguage(uri, exchange);
final String servicePath = applySimpleLanguage(contextPath, exchange);
final String serviceScheme = applySimpleLanguage(scheme, exchange);
message.setHeader(ServiceCallConstants.SERVICE_CALL_URI, serviceUri);
message.setHeader(ServiceCallConstants.SERVICE_CALL_CONTEXT_PATH, servicePath);
message.setHeader(ServiceCallConstants.SERVICE_CALL_SCHEME, serviceScheme);
message.setHeader(ServiceCallConstants.SERVICE_NAME, serviceName);
try {
return loadBalancer.process(serviceName, server -> execute(server, exchange, callback));
} catch (Exception e) {
exchange.setException(e);
return true;
}
}
private boolean execute(ServiceDefinition service, Exchange exchange, AsyncCallback callback) throws Exception {
final Message message = exchange.getIn();
final String host = service.getHost();
final int port = service.getPort();
final Map meta = service.getMetadata();
LOGGER.debug("Service {} active at server: {}:{}", name, host, port);
// set selected server as header
message.setHeader(ServiceCallConstants.SERVICE_HOST, host);
message.setHeader(ServiceCallConstants.SERVICE_PORT, port > 0 ? port : null);
message.setHeader(ServiceCallConstants.SERVICE_NAME, service.getName());
message.setHeader(ServiceCallConstants.SERVICE_META, meta);
// If context path is not set on service call definition, reuse the one from
// ServiceDefinition, if any
message.getHeaders().compute(ServiceCallConstants.SERVICE_CALL_CONTEXT_PATH, (k, v) ->
v == null ? meta.get(ServiceDefinition.SERVICE_META_PATH) : v
);
// If port is not set on service call definition, reuse the one from
// ServiceDefinition, if any
message.getHeaders().compute(ServiceCallConstants.SERVICE_PORT, (k, v) ->
v == null ? meta.get(ServiceDefinition.SERVICE_META_PORT) : v
);
// use the dynamic send processor to call the service
return processor.process(exchange, callback);
}
/**
* This function applies the simple language to the given expression.
*
* @param expression the expression
* @param exchange the exchange
* @return the computed expression
*/
private String applySimpleLanguage(String expression, Exchange exchange) {
return SimpleLanguage.hasSimpleFunction(expression)
? SimpleLanguage.simple(expression).evaluate(exchange, String.class)
: expression;
}
}