JAX-RS: Failover
Starting from CXF 2.4.1, CXF JAX-RS clients can be configured for them to become failover-capable.
Core CXF Failover and Load Distribution features are supported.
Failover
Proxies and WebClients can be configured to failover to alternate addresses in case of connection-related failures.
Sequential and Random strategies are supported and implementers can build more sophisticated failover features by retrieving
alternate addresses from locators and other intermediaries.
Spring
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:jaxrs="http://cxf.apache.org/jaxrs" xmlns:util="http://www.springframework.org/schema/util" xsi:schemaLocation=" http://cxf.apache.org/jaxrs http://cxf.apache.org/schemas/jaxrs.xsd http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util.xsd"> <bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"/> <util:list id="addressList"> <value>http://localhost:${testutil.ports.Server.1}/rest</value> <value>http://localhost:${testutil.ports.Server.2}/rest</value> <value>http://localhost:${testutil.ports.Server.3}/rest</value> </util:list> <bean id="SequentialAddresses" class="org.apache.cxf.clustering.SequentialStrategy"> <property name="alternateAddresses"> <ref bean="addressList"/> </property> </bean> <bean id="RandomAddresses" class="org.apache.cxf.clustering.RandomStrategy"> <property name="alternateAddresses"> <ref bean="addressList"/> </property> </bean> <bean id="failover1" class="org.apache.cxf.jaxrs.features.clustering.FailoverFeature"> <property name="strategy" ref="SequentialAddresses"/> </bean> <bean id="failover2" class="org.apache.cxf.jaxrs.features.clustering.FailoverFeature"> <property name="strategy" ref="RandomAddresses"/> </bean> <jaxrs:client id="failoverSequential" address="http://localhost:8080/initialAddress"> <jaxrs:features> <ref bean="failover1"/> </jaxrs:features> </jaxrs:client> <jaxrs:client id="failoverRandom" address="http://localhost:8080/initialAddress"> <jaxrs:features> <ref bean="failover2"/> </jaxrs:features> </jaxrs:client> <bean id="myWebClient" class="org.apache.cxf.jaxrs.client.JAXRSClientFactoryBean" factory-method="createWebClient"> <property name="address" value="http://some.base.url.that.responds/" /> <property name="features"> <util:list> <ref bean="failover1"/> </util:list> </property> </bean> </beans>
Note that failover feature for jaxrs:client gets configured nearly exactly the same way as it's done for JAX-WS clients. The difference at this stage is that feature class name (org.apache.cxf.jaxrs.features.clustering.FailoverFeature) and a 'strategy' property are 'hidden' for JAX-WS clients due to the use of Spring handlers, example:
<jaxws:client name="{http://cxf.apache.org/greeter_control}ReplicatedPortA" createdFromAPI="true"> <jaxws:features> <clustering:failover> <clustering:strategy> <ref bean="SequentialAddresses"/> </clustering:strategy> </clustering:failover> </jaxws:features> </jaxws:client>
In other words, JAX-RS clients can not use clustering:failover/clustering:strategy only at this stage, the rest the same. An efoort will be undertaken to make sure this configuration becomes identical for JAX-WS and JAX-RS clients.
Code
org.apache.cxf.jaxrs.features.clustering.FailoverFeature feature = new org.apache.cxf.jaxrs.features.clustering.FailoverFeature(); List<String> alternateAddresses = new ArrayList<String>(); // addresses are alternate addresses provided at start-up for (String s : address) { alternateAddresses.add(s); } SequentialStrategy strategy = new SequentialStrategy(); strategy.setAlternateAddresses(alternateAddresses); feature.setStrategy(strategy); JAXRSClientFactoryBean bean = new JAXRSClientFactoryBean(); bean.setAddress("http://localhost:8080/inactive-replica"); List<AbstractFeature> features = new ArrayList<AbstractFeature>(); features.add(feature); bean.setFeatures(features); // create proxy: bean.create(BookStore.class); // create web client bean.createWebClient();
Load Distribution
CXF Load Distribution feature is a failover feature which can iterate where alternate addresses not only in case of failures but also after a successful invocation has been done.
It is configured for CXF JAX-RS clients exactly the same way Failover feature is configured, the only difference that a (conduit) selector property is also specified, example:
<beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:jaxrs="http://cxf.apache.org/jaxrs" xmlns:util="http://www.springframework.org/schema/util" xsi:schemaLocation=" http://cxf.apache.org/jaxrs http://cxf.apache.org/schemas/jaxrs.xsd http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util.xsd"> <bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"/> <util:list id="addressList"> <value>http://localhost:${testutil.ports.Server.1}/rest</value> <value>http://localhost:${testutil.ports.Server.2}/rest</value> <value>http://localhost:${testutil.ports.Server.3}/rest</value> </util:list> <bean id="SequentialAddresses" class="org.apache.cxf.clustering.SequentialStrategy"> <property name="alternateAddresses"> <ref bean="addressList"/> </property> </bean> <bean id="targetSelector" class="org.apache.cxf.clustering.LoadDistributorTargetSelector"/> <jaxrs:client id="loadDistributionSequential" address="http://localhost:8080/initialAddress"> <jaxrs:features> <bean class="org.apache.cxf.jaxrs.features.clustering.FailoverFeature"> <property name="strategy" ref="SequentialAddresses"/> <property name="selector" ref="targetSelector"/> </bean> </jaxrs:features> </jaxrs:client>
the selector can be set from code like this:
org.apache.cxf.jaxrs.features.clustering.FailoverFeature feature = new org.apache.cxf.jaxrs.features.clustering.FailoverFeature(); feature.setSelector(new org.apache.cxf.clustering.LoadDistributorTargetSelector());