INT-2863 Add Release Strategy to Resequencer

- allow the configuration of release strategies on resequencers
-- adjust the xsd to allow the definition of a release strategy
-- move release strategy parsing to AbstractCorrelatingMessageHandlerParser
-- add unit tests

For reference see: https://jira.springsource.org/browse/INT-2863

INT-2863 Polishing

Fix white space; add @author; update copyright.

INT-2863 Resequencer/Aggregator Docs

Add docs for correlation and release strategis to Resequencer.

Add *.expression docs to Aggregator.

spring-integration-core/src/test/java/org/springframework/integration/config/ResequencerParserTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2012 the original author or authors.
+ * Copyright 2002-2013 the original author or authors.
  *
  * Licensed 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
@@ -18,18 +18,23 @@ import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
 import static org.springframework.integration.test.util.TestUtils.getPropertyValue;
 
+import java.util.List;
+
 import org.junit.Before;
 import org.junit.Test;
-
 import org.springframework.context.ApplicationContext;
 import org.springframework.context.support.ClassPathXmlApplicationContext;
 import org.springframework.integration.Message;
 import org.springframework.integration.MessageChannel;
 import org.springframework.integration.aggregator.CorrelationStrategy;
 import org.springframework.integration.aggregator.MethodInvokingCorrelationStrategy;
+import org.springframework.integration.aggregator.MethodInvokingReleaseStrategy;
+import org.springframework.integration.aggregator.ReleaseStrategy;
 import org.springframework.integration.aggregator.ResequencingMessageHandler;
 import org.springframework.integration.channel.NullChannel;
 import org.springframework.integration.endpoint.EventDrivenConsumer;
+import org.springframework.integration.store.MessageGroup;
+import org.springframework.integration.store.SimpleMessageGroup;
 import org.springframework.integration.support.MessageBuilder;
 import org.springframework.integration.test.util.TestUtils;
 
@@ -38,6 +43,7 @@ import org.springframework.integration.test.util.TestUtils;
  * @author Mark Fisher
  * @author Dave Syer
  * @author Oleg Zhurakousky
+ * @author Stefan Ferstl
  */
 public class ResequencerParserTests {
 
@@ -94,6 +100,34 @@ public class ResequencerParserTests {
 				.getBean("testCorrelationStrategy"), getPropertyValue(resequencer, "correlationStrategy"));
 	}
 
+	@Test
+	public void testReleaseStrategyRefOnly() throws Exception {
+		EventDrivenConsumer endpoint = (EventDrivenConsumer) context.getBean("resequencerWithReleaseStrategyRefOnly");
+		ResequencingMessageHandler resequencer = getPropertyValue(endpoint, "handler", ResequencingMessageHandler.class);
+		assertEquals("The ResequencerEndpoint is not configured with the appropriate ReleaseStrategy",
+				context.getBean("testReleaseStrategy"), getPropertyValue(resequencer, "releaseStrategy"));
+	}
+
+	@Test
+	public void testReleaseStrategyRefAndMethod() throws Exception {
+		EventDrivenConsumer endpoint = (EventDrivenConsumer) context
+				.getBean("resequencerWithReleaseStrategyRefAndMethod");
+		ResequencingMessageHandler resequencer = getPropertyValue(endpoint, "handler", ResequencingMessageHandler.class);
+
+		Object releaseStrategyBean = context.getBean("testReleaseStrategyPojo");
+		assertTrue("Release strategy is not of the expected type",
+				releaseStrategyBean instanceof TestReleaseStrategyPojo);
+		TestReleaseStrategyPojo expectedReleaseStrategy = (TestReleaseStrategyPojo) releaseStrategyBean;
+
+		int currentInvocationCount = expectedReleaseStrategy.invocationCount;
+		ReleaseStrategy effectiveReleaseStrategy = (ReleaseStrategy) getPropertyValue(resequencer, "releaseStrategy");
+		assertTrue("The release strategy is expected to be a MethodInvokingReleaseStrategy",
+				effectiveReleaseStrategy instanceof MethodInvokingReleaseStrategy);
+		effectiveReleaseStrategy.canRelease(new SimpleMessageGroup("test"));
+		assertEquals("The ResequencerEndpoint was not invoked the expected number of times;",
+				currentInvocationCount + 1, expectedReleaseStrategy.invocationCount);
+	}
+
 	@Test
 	public void shouldSetReleasePartialSequencesFlag(){
 				EventDrivenConsumer endpoint = (EventDrivenConsumer) context.getBean("completelyDefinedResequencer");
@@ -137,4 +171,19 @@ public class ResequencerParserTests {
 		}
 	}
 
+	static class TestReleaseStrategy implements ReleaseStrategy {
+		public boolean canRelease(MessageGroup group) {
+			return true;
+		}
+	}
+
+	static class TestReleaseStrategyPojo {
+		private int invocationCount = 0;
+
+		public boolean bar(List<Message<?>> messages) {
+			invocationCount++;
+			return true;
+		}
+	}
+
 }

spring-integration-core/src/test/java/org/springframework/integration/config/resequencerParserTests.xml

@@ -46,10 +46,24 @@
 		correlation-strategy="testCorrelationStrategyPojo"
 		correlation-strategy-method="foo"/>
 
+	<resequencer id="resequencerWithReleaseStrategyRefOnly"
+		input-channel="inputChannel5"
+		release-strategy="testReleaseStrategy"/>
+
+	<resequencer id="resequencerWithReleaseStrategyRefAndMethod"
+		input-channel="inputChannel6"
+		release-strategy="testReleaseStrategyPojo"
+		release-strategy-method="bar"/>
+
 	<beans:bean id="testCorrelationStrategy"
 		class="org.springframework.integration.config.ResequencerParserTests$TestCorrelationStrategy"/>
 
 	<beans:bean id="testCorrelationStrategyPojo"
 		class="org.springframework.integration.config.ResequencerParserTests$TestCorrelationStrategyPojo"/>
 
+	<beans:bean id="testReleaseStrategy"
+		class="org.springframework.integration.config.ResequencerParserTests$TestReleaseStrategy" />
+
+	<beans:bean id="testReleaseStrategyPojo"
+		class="org.springframework.integration.config.ResequencerParserTests$TestReleaseStrategyPojo" />
 </beans:beans>