001/** 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017package org.apache.camel.model.loadbalancer; 018 019import java.util.ArrayList; 020import java.util.List; 021 022import javax.xml.bind.annotation.XmlAccessType; 023import javax.xml.bind.annotation.XmlAccessorType; 024import javax.xml.bind.annotation.XmlAttribute; 025import javax.xml.bind.annotation.XmlElement; 026import javax.xml.bind.annotation.XmlRootElement; 027import javax.xml.bind.annotation.XmlTransient; 028 029import org.apache.camel.model.LoadBalancerDefinition; 030import org.apache.camel.processor.loadbalancer.FailOverLoadBalancer; 031import org.apache.camel.processor.loadbalancer.LoadBalancer; 032import org.apache.camel.spi.Metadata; 033import org.apache.camel.spi.RouteContext; 034import org.apache.camel.util.ObjectHelper; 035 036/** 037 * Failover load balancer 038 * 039 * The failover load balancer is capable of trying the next processor in case an Exchange failed with an exception during processing. 040 * You can constrain the failover to activate only when one exception of a list you specify occurs. 041 * If you do not specify a list any exception will cause fail over to occur. 042 * This balancer uses the same strategy for matching exceptions as the Exception Clause does for the onException. 043 */ 044@Metadata(label = "eip,routing,loadbalance") 045@XmlRootElement(name = "failover") 046@XmlAccessorType(XmlAccessType.FIELD) 047public class FailoverLoadBalancerDefinition extends LoadBalancerDefinition { 048 @XmlTransient 049 private List<Class<?>> exceptionTypes = new ArrayList<>(); 050 @XmlElement(name = "exception") 051 private List<String> exceptions = new ArrayList<>(); 052 @XmlAttribute 053 private Boolean roundRobin; 054 @XmlAttribute 055 private Boolean sticky; 056 @XmlAttribute @Metadata(defaultValue = "-1") 057 private Integer maximumFailoverAttempts; 058 059 public FailoverLoadBalancerDefinition() { 060 } 061 062 @Override 063 protected LoadBalancer createLoadBalancer(RouteContext routeContext) { 064 FailOverLoadBalancer answer; 065 066 List<Class<?>> classes = new ArrayList<>(); 067 if (!exceptionTypes.isEmpty()) { 068 classes.addAll(exceptionTypes); 069 } else if (!exceptions.isEmpty()) { 070 for (String name : exceptions) { 071 Class<?> type = routeContext.getCamelContext().getClassResolver().resolveClass(name); 072 if (type == null) { 073 throw new IllegalArgumentException("Cannot find class: " + name + " in the classpath"); 074 } 075 if (!ObjectHelper.isAssignableFrom(Throwable.class, type)) { 076 throw new IllegalArgumentException("Class is not an instance of Throwable: " + type); 077 } 078 classes.add(type); 079 } 080 } 081 if (classes.isEmpty()) { 082 answer = new FailOverLoadBalancer(); 083 } else { 084 answer = new FailOverLoadBalancer(classes); 085 } 086 087 if (getMaximumFailoverAttempts() != null) { 088 answer.setMaximumFailoverAttempts(getMaximumFailoverAttempts()); 089 } 090 if (roundRobin != null) { 091 answer.setRoundRobin(roundRobin); 092 } 093 if (sticky != null) { 094 answer.setSticky(sticky); 095 } 096 097 return answer; 098 } 099 100 public List<String> getExceptions() { 101 return exceptions; 102 } 103 104 /** 105 * A list of class names for specific exceptions to monitor. 106 * If no exceptions is configured then all exceptions is monitored 107 */ 108 public void setExceptions(List<String> exceptions) { 109 this.exceptions = exceptions; 110 } 111 112 public List<Class<?>> getExceptionTypes() { 113 return exceptionTypes; 114 } 115 116 /** 117 * A list of specific exceptions to monitor. 118 * If no exceptions is configured then all exceptions is monitored 119 */ 120 public void setExceptionTypes(List<Class<?>> exceptionTypes) { 121 this.exceptionTypes = exceptionTypes; 122 } 123 124 public Boolean getRoundRobin() { 125 return roundRobin; 126 } 127 128 /** 129 * Whether or not the failover load balancer should operate in round robin mode or not. 130 * If not, then it will always start from the first endpoint when a new message is to be processed. 131 * In other words it restart from the top for every message. 132 * If round robin is enabled, then it keeps state and will continue with the next endpoint in a round robin fashion. 133 * <p/> 134 * You can also enable sticky mode together with round robin, if so then it will pick the last known good endpoint 135 * to use when starting the load balancing (instead of using the next when starting). 136 */ 137 public void setRoundRobin(Boolean roundRobin) { 138 this.roundRobin = roundRobin; 139 } 140 141 public Boolean getSticky() { 142 return sticky; 143 } 144 145 /** 146 * Whether or not the failover load balancer should operate in sticky mode or not. 147 * If not, then it will always start from the first endpoint when a new message is to be processed. 148 * In other words it restart from the top for every message. 149 * If sticky is enabled, then it keeps state and will continue with the last known good endpoint. 150 * <p/> 151 * You can also enable sticky mode together with round robin, if so then it will pick the last known good endpoint 152 * to use when starting the load balancing (instead of using the next when starting). 153 */ 154 public void setSticky(Boolean sticky) { 155 this.sticky = sticky; 156 } 157 158 public Integer getMaximumFailoverAttempts() { 159 return maximumFailoverAttempts; 160 } 161 162 /** 163 * A value to indicate after X failover attempts we should exhaust (give up). 164 * Use -1 to indicate never give up and continuously try to failover. Use 0 to never failover. 165 * And use e.g. 3 to failover at most 3 times before giving up. 166 * his option can be used whether or not roundRobin is enabled or not. 167 */ 168 public void setMaximumFailoverAttempts(Integer maximumFailoverAttempts) { 169 this.maximumFailoverAttempts = maximumFailoverAttempts; 170 } 171 172 @Override 173 public String toString() { 174 return "FailoverLoadBalancer"; 175 } 176}