INTSAMPLES-64 Poller Sample using custom Trigger

For reference: https://jira.springsource.org/browse/INTSAMPLES-64

Shows how the polling period can be changed at runtime using a custom trigger.

intermediate/dynamic-poller/src/main/java/org/springframework/integration/samples/poller/DynamicPeriodicTrigger.java

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+/*
+ * Copyright 2002-2012 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
+ *
+ *      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.springframework.integration.samples.poller;
+
+import java.util.Date;
+import java.util.concurrent.TimeUnit;
+
+import org.springframework.scheduling.Trigger;
+import org.springframework.scheduling.TriggerContext;
+import org.springframework.scheduling.support.PeriodicTrigger;
+import org.springframework.util.Assert;
+
+
+/**
+ * This is a dynamically changeable {@link Trigger}. It is based on the 
+ * {@link PeriodicTrigger} implementations. However, the fields of this dynamic 
+ * trigger are not final and the properties can be inspected and set via 
+ * explicit getters and setters.
+ * 
+ * @author Gunnar Hillert
+ *
+ */
+public class DynamicPeriodicTrigger implements Trigger {
+	
+	private volatile long period;
+
+	private volatile TimeUnit timeUnit;
+
+	private volatile long initialDelay = 0;
+
+	private volatile boolean fixedRate = false;
+
+	/**
+	 * Create a trigger with the given period in milliseconds.
+	 */
+	public DynamicPeriodicTrigger(long period) {
+		this(period, null);
+	}
+
+	/**
+	 * Create a trigger with the given period and time unit. The time unit will
+	 * apply not only to the period but also to any 'initialDelay' value, if
+	 * configured on this Trigger later via {@link #setInitialDelay(long)}.
+	 */
+	public DynamicPeriodicTrigger(long period, TimeUnit timeUnit) {
+		Assert.isTrue(period >= 0, "period must not be negative");
+		this.timeUnit = (timeUnit != null) ? timeUnit : TimeUnit.MILLISECONDS;
+		this.period = this.timeUnit.toMillis(period);
+	}
+
+	/**
+	 * Specify the delay for the initial execution. It will be evaluated in
+	 * terms of this trigger's {@link TimeUnit}. If no time unit was explicitly
+	 * provided upon instantiation, the default is milliseconds. 
+	 */
+	public void setInitialDelay(long initialDelay) {
+		this.initialDelay = this.timeUnit.toMillis(initialDelay);
+	}
+
+	/**
+	 * Specify whether the periodic interval should be measured between the
+	 * scheduled start times rather than between actual completion times.
+	 * The latter, "fixed delay" behavior, is the default.
+	 */
+	public void setFixedRate(boolean fixedRate) {
+		this.fixedRate = fixedRate;
+	}
+
+	/**
+	 * Returns the time after which a task should run again.
+	 */
+	public Date nextExecutionTime(TriggerContext triggerContext) {
+		if (triggerContext.lastScheduledExecutionTime() == null) {
+			return new Date(System.currentTimeMillis() + this.initialDelay);
+		}
+		else if (this.fixedRate) {
+			return new Date(triggerContext.lastScheduledExecutionTime().getTime() + this.period);
+		}
+		return new Date(triggerContext.lastCompletionTime().getTime() + this.period);
+	}
+
+	public long getPeriod() {
+		return period;
+	}
+
+	public void setPeriod(long period) {
+		this.period = period;
+	}
+
+	public TimeUnit getTimeUnit() {
+		return timeUnit;
+	}
+
+	public void setTimeUnit(TimeUnit timeUnit) {
+		this.timeUnit = timeUnit;
+	}
+
+	public long getInitialDelay() {
+		return initialDelay;
+	}
+
+	public boolean isFixedRate() {
+		return fixedRate;
+	}
+
+	@Override
+	public boolean equals(Object obj) {
+		if (this == obj) {
+			return true;
+		}
+		if (!(obj instanceof DynamicPeriodicTrigger)) {
+			return false;
+		}
+		DynamicPeriodicTrigger other = (DynamicPeriodicTrigger) obj;
+		return this.fixedRate == other.fixedRate
+				&& this.initialDelay == other.initialDelay
+				&& this.period == other.period;
+	}
+
+	@Override
+	public int hashCode() {
+		return (this.fixedRate ? 14 : 41) +
+				(int) (38 * this.period) +
+				(int) (43 * this.initialDelay); 
+	}
+
+}

intermediate/dynamic-poller/src/main/java/org/springframework/integration/samples/poller/Main.java

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+/*
+ * Copyright 2002-2012 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
+ *
+ *      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.springframework.integration.samples.poller;
+
+import java.util.Scanner;
+
+import org.apache.log4j.Logger;
+import org.springframework.context.support.AbstractApplicationContext;
+import org.springframework.context.support.ClassPathXmlApplicationContext;
+
+/**
+ * Starts the Spring Context and will initialize the Spring Integration routes.
+ *
+ * @author Gunnar Hillert
+ * @version 1.0
+ *
+ */
+public final class Main {
+
+    private static final Logger LOGGER = Logger.getLogger(Main.class);
+
+    private Main() { }
+
+    /**
+     * Load the Spring Integration Application Context
+     *
+     * @param args - command line arguments
+     */
+    public static void main(final String... args) {
+
+        LOGGER.info("\n=========================================================="
+                  + "\n                                                          "
+                  + "\n Welcome to the Spring Integration Dynamic Poller Sample! "
+                  + "\n                                                          "
+                  + "\n    For more information please visit:                    "
+                  + "\n    http://www.springsource.org/spring-integration        "
+                  + "\n                                                          "
+                  + "\n==========================================================" );
+
+        final AbstractApplicationContext context =
+                new ClassPathXmlApplicationContext("classpath:META-INF/spring/integration/*-context.xml");
+
+        context.registerShutdownHook();
+
+        final Scanner scanner = new Scanner(System.in);
+
+        final DynamicPeriodicTrigger trigger = context.getBean(DynamicPeriodicTrigger.class);
+
+        LOGGER.info("\n========================================================="
+                  + "\n                                                         "
+                  + "\n    Please press 'q + Enter' to quit the application.    "
+                  + "\n                                                         "
+                  + "\n=========================================================" );
+
+        System.out.print("Please enter a non-negative numeric value and press <enter>: ");
+        
+        while (!scanner.hasNext("q")) {
+        	
+        	int triggerPeriod = scanner.nextInt();
+        	
+        	System.out.println(String.format("Setting trigger period to '%s' ms", triggerPeriod));
+        	
+        	trigger.setPeriod(triggerPeriod);
+            
+        	System.out.print("Please enter a non-negative numeric value and press <enter>: ");
+        }
+
+        LOGGER.info("Exiting application...bye.");
+
+        System.exit(0);
+
+    }
+}

intermediate/dynamic-poller/src/main/resources/META-INF/spring/integration/spring-integration-context.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<beans xmlns="http://www.springframework.org/schema/beans"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd
+        http://www.springframework.org/schema/integration http://www.springframework.org/schema/integration/spring-integration-2.1.xsd
+        http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task.xsd"
+    xmlns:int="http://www.springframework.org/schema/integration"
+    xmlns:task="http://www.springframework.org/schema/task">
+
+    <int:inbound-channel-adapter expression="T(java.lang.System).currentTimeMillis()" channel="logger">
+        <int:poller max-messages-per-poll="1" trigger="dynamicTrigger" />
+    </int:inbound-channel-adapter>
+
+    <bean id="dynamicTrigger" class="org.springframework.integration.samples.poller.DynamicPeriodicTrigger">
+        <constructor-arg name="period" value="5000"/>
+    </bean>
+
+    <int:logging-channel-adapter id="logger" logger-name="org.springframework.integration.samples.poller"/>
+
+    <task:executor id="executor" queue-capacity="20" pool-size="5-20"/>
+</beans>

intermediate/dynamic-poller/src/main/resources/log4j.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
+<log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">
+
+	<!-- Appenders -->
+	<appender name="console" class="org.apache.log4j.ConsoleAppender">
+		<param name="Target" value="System.out" />
+		<layout class="org.apache.log4j.PatternLayout">
+			<param name="ConversionPattern" value="%-5p: %c - %m%n" />
+		</layout>
+	</appender>
+
+	<!-- Loggers -->
+	<logger name="org.springframework">
+		<level value="warn" />
+	</logger>
+
+	<logger name="org.springframework.integration.samples">
+		<level value="debug" />
+	</logger>
+
+	<!-- Root Logger -->
+	<root>
+		<priority value="warn" />
+		<appender-ref ref="console" />
+	</root>
+
+</log4j:configuration>