Merge pull request #8125 from eugenp/revert-8119-BAEL-3275-2

Revert "BAEL-3275: Using blocking queue for pub-sub"

spring-integration/src/main/java/com/baeldung/dsl/JavaDSLFileCopyConfig.java

@@ -0,0 +1,153 @@
+package com.baeldung.dsl;
+
+import java.io.File;
+import java.util.Scanner;
+import java.util.concurrent.TimeUnit;
+
+import org.springframework.context.annotation.AnnotationConfigApplicationContext;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.support.AbstractApplicationContext;
+import org.springframework.integration.annotation.IntegrationComponentScan;
+import org.springframework.integration.channel.PriorityChannel;
+import org.springframework.integration.config.EnableIntegration;
+import org.springframework.integration.core.GenericSelector;
+import org.springframework.integration.core.MessageSource;
+import org.springframework.integration.dsl.IntegrationFlow;
+import org.springframework.integration.dsl.IntegrationFlows;
+import org.springframework.integration.dsl.Pollers;
+import org.springframework.integration.dsl.channel.MessageChannels;
+import org.springframework.integration.file.FileReadingMessageSource;
+import org.springframework.integration.file.FileWritingMessageHandler;
+import org.springframework.messaging.MessageChannel;
+import org.springframework.messaging.MessageHandler;
+
+/**
+ * JavaDSLFileCopyConfig contains various Integration Flows created from various spring integration components.
+ * Activate only one flow at a time by un-commenting @Bean annotation from IntegrationFlow beans. 
+ * <p>
+ * Different flows are :<br>
+ * - {@link #fileMover()} - default app - activated<br>
+ * - {@link #fileMoverWithLambda()} - app with file writing expressions as lambda<br>
+ * - {@link #fileMoverWithPriorityChannel()} - app with priority channel<br>
+ * - {@link #fileReader()}, {@link #fileWriter()}, {@link #anotherFileWriter()} - app with bridge
+ */
+@Configuration
+@EnableIntegration
+@IntegrationComponentScan
+public class JavaDSLFileCopyConfig {
+
+    public static final String INPUT_DIR = "source";
+    public static final String OUTPUT_DIR = "target";
+    public static final String OUTPUT_DIR2 = "target2";
+
+    @Bean
+    public MessageSource<File> sourceDirectory() {
+        FileReadingMessageSource messageSource = new FileReadingMessageSource();
+        messageSource.setDirectory(new File(INPUT_DIR));
+        return messageSource;
+    }
+
+    @Bean
+    public GenericSelector<File> onlyJpgs() {
+        return new GenericSelector<File>() {
+
+            @Override
+            public boolean accept(File source) {
+              return source.getName()
+                .endsWith(".jpg");
+            }
+        };
+    }
+
+    @Bean
+    public MessageHandler targetDirectory() {
+        FileWritingMessageHandler handler = new FileWritingMessageHandler(new File(OUTPUT_DIR));
+        handler.setExpectReply(false); // end of pipeline, reply not needed
+        return handler;
+    }
+    
+    @Bean
+    public IntegrationFlow fileMover() {
+        return IntegrationFlows.from(sourceDirectory(), configurer -> configurer.poller(Pollers.fixedDelay(10000)))
+            .filter(onlyJpgs())
+            .handle(targetDirectory())
+            .get();
+    }
+
+    // @Bean
+    public IntegrationFlow fileMoverWithLambda() {
+        return IntegrationFlows.from(sourceDirectory(), configurer -> configurer.poller(Pollers.fixedDelay(10000)))
+            .filter(message -> ((File) message).getName()
+                .endsWith(".jpg"))
+            .handle(targetDirectory())
+            .get();
+    }
+
+    @Bean
+    public PriorityChannel alphabetically() {
+        return new PriorityChannel(1000, (left, right) -> ((File) left.getPayload()).getName()
+            .compareTo(((File) right.getPayload()).getName()));
+    }
+
+    // @Bean
+    public IntegrationFlow fileMoverWithPriorityChannel() {
+        return IntegrationFlows.from(sourceDirectory())
+            .filter(onlyJpgs())
+            .channel("alphabetically")
+            .handle(targetDirectory())
+            .get();
+    }
+
+    @Bean
+    public MessageHandler anotherTargetDirectory() {
+        FileWritingMessageHandler handler = new FileWritingMessageHandler(new File(OUTPUT_DIR2));
+        handler.setExpectReply(false); // end of pipeline, reply not needed
+        return handler;
+    }
+
+    @Bean
+    public MessageChannel holdingTank() {
+        return MessageChannels.queue().get();
+    }
+    
+    // @Bean
+    public IntegrationFlow fileReader() {
+        return IntegrationFlows.from(sourceDirectory(), configurer -> configurer.poller(Pollers.fixedDelay(10)))
+            .filter(onlyJpgs())
+            .channel("holdingTank")
+            .get();
+    }
+
+    // @Bean
+    public IntegrationFlow fileWriter() {
+        return IntegrationFlows.from("holdingTank")
+            .bridge(e -> e.poller(Pollers.fixedRate(1, TimeUnit.SECONDS, 20)))
+            .handle(targetDirectory())
+            .get();
+    }
+
+    // @Bean
+    public IntegrationFlow anotherFileWriter() {
+        return IntegrationFlows.from("holdingTank")
+            .bridge(e -> e.poller(Pollers.fixedRate(2, TimeUnit.SECONDS, 10)))
+            .handle(anotherTargetDirectory())
+            .get();
+    }
+
+    public static void main(final String... args) {
+        final AbstractApplicationContext context = new AnnotationConfigApplicationContext(JavaDSLFileCopyConfig.class);
+        context.registerShutdownHook();
+        final Scanner scanner = new Scanner(System.in);
+        System.out.print("Please enter a string and press <enter>: ");
+        while (true) {
+            final String input = scanner.nextLine();
+            if ("q".equals(input.trim())) {
+                context.close();
+                scanner.close();
+                break;
+            }
+        }
+        System.exit(0);
+    }
+}

spring-integration/src/main/java/com/baeldung/samples/FileCopyConfig.java

@@ -0,0 +1,73 @@
+package com.baeldung.samples;
+
+import java.io.File;
+import java.util.Scanner;
+
+import org.springframework.context.annotation.AnnotationConfigApplicationContext;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.support.AbstractApplicationContext;
+import org.springframework.integration.annotation.InboundChannelAdapter;
+import org.springframework.integration.annotation.Poller;
+import org.springframework.integration.annotation.ServiceActivator;
+import org.springframework.integration.channel.DirectChannel;
+import org.springframework.integration.config.EnableIntegration;
+import org.springframework.integration.core.MessageSource;
+import org.springframework.integration.file.FileReadingMessageSource;
+import org.springframework.integration.file.FileWritingMessageHandler;
+import org.springframework.integration.file.filters.SimplePatternFileListFilter;
+import org.springframework.integration.file.support.FileExistsMode;
+import org.springframework.messaging.MessageChannel;
+import org.springframework.messaging.MessageHandler;
+
+@Configuration
+@EnableIntegration
+public class FileCopyConfig {
+
+    public final String INPUT_DIR = "source";
+    public final String OUTPUT_DIR = "target";
+    public final String FILE_PATTERN = "*.jpg";
+
+    @Bean
+    public MessageChannel fileChannel() {
+        return new DirectChannel();
+    }
+
+    @Bean
+    @InboundChannelAdapter(value = "fileChannel", poller = @Poller(fixedDelay = "10000"))
+    public MessageSource<File> fileReadingMessageSource() {
+        FileReadingMessageSource sourceReader = new FileReadingMessageSource();
+        sourceReader.setDirectory(new File(INPUT_DIR));
+        sourceReader.setFilter(new SimplePatternFileListFilter(FILE_PATTERN));
+        return sourceReader;
+    }
+
+    @Bean
+    @ServiceActivator(inputChannel = "fileChannel")
+    public MessageHandler fileWritingMessageHandler() {
+        FileWritingMessageHandler handler = new FileWritingMessageHandler(new File(OUTPUT_DIR));
+        handler.setFileExistsMode(FileExistsMode.REPLACE);
+        handler.setExpectReply(false);
+        return handler;
+    }
+
+    public static void main(final String... args) {
+        final AbstractApplicationContext context = new AnnotationConfigApplicationContext(FileCopyConfig.class);
+        context.registerShutdownHook();
+        final Scanner scanner = new Scanner(System.in);
+        System.out.print("Please enter a string and press <enter>: ");
+        while (true) {
+            final String input = scanner.nextLine();
+            if ("q".equals(input.trim())) {
+                context.close();
+                scanner.close();
+                break;
+            }
+        }
+        System.exit(0);
+    }
+
+}
+    
+
+

spring-integration/src/main/java/com/baeldung/samples/endpoints/Activator.java

@@ -0,0 +1,7 @@
+package com.baeldung.samples.endpoints;
+
+public interface Activator<T> {
+	
+	public void handleMessage(T input);
+
+}

spring-integration/src/main/java/com/baeldung/samples/endpoints/ActivatorImpl.java

@@ -0,0 +1,20 @@
+package com.baeldung.samples.endpoints;
+
+import java.io.File;
+import java.util.logging.Logger;
+
+import org.springframework.integration.IntegrationMessageHeaderAccessor;
+import org.springframework.messaging.Message;
+
+public class ActivatorImpl implements Activator<Message<File>>  {
+
+	@Override
+	public void handleMessage(Message<File> input) {
+		File filePayload = input.getPayload();
+		IntegrationMessageHeaderAccessor accessor = new IntegrationMessageHeaderAccessor(input);
+		Logger.getAnonymousLogger().info("The file size "+filePayload.length());
+		Logger.getAnonymousLogger().info("The time of the message "+accessor.getTimestamp());
+		
+	}
+
+}

spring-integration/src/main/java/com/baeldung/si/security/MessageConsumer.java

@@ -0,0 +1,45 @@
+package com.baeldung.si.security;
+
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.logging.Logger;
+
+import org.springframework.integration.annotation.ServiceActivator;
+import org.springframework.messaging.Message;
+import org.springframework.stereotype.Service;
+
+@Service
+public class MessageConsumer {
+
+    private String messageContent;
+
+    private Map<String, String> messagePSContent = new ConcurrentHashMap<>();
+
+    public String getMessageContent() {
+        return messageContent;
+    }
+
+    public void setMessageContent(String messageContent) {
+        this.messageContent = messageContent;
+    }
+
+    public Map<String, String> getMessagePSContent() {
+        return messagePSContent;
+    }
+
+    public void setMessagePSContent(Map<String, String> messagePSContent) {
+        this.messagePSContent = messagePSContent;
+    }
+
+    @ServiceActivator(inputChannel = "endDirectChannel")
+    public void endDirectFlow(Message<?> message) {
+        setMessageContent(message.getPayload().toString());
+    }
+
+    @ServiceActivator(inputChannel = "finalPSResult")
+    public void endPSFlow(Message<?> message) {
+        Logger.getAnonymousLogger().info(Thread.currentThread().getName() + " has completed ---------------------------");
+        messagePSContent.put(Thread.currentThread().getName(), (String) message.getPayload());
+    }
+
+}

spring-integration/src/main/java/com/baeldung/si/security/SecuredDirectChannel.java

@@ -0,0 +1,50 @@
+package com.baeldung.si.security;
+
+import java.util.logging.Logger;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.integration.annotation.ServiceActivator;
+import org.springframework.integration.channel.DirectChannel;
+import org.springframework.integration.config.EnableIntegration;
+import org.springframework.integration.security.channel.ChannelSecurityInterceptor;
+import org.springframework.integration.security.channel.SecuredChannel;
+import org.springframework.messaging.Message;
+import org.springframework.security.access.AccessDecisionManager;
+import org.springframework.security.access.prepost.PreAuthorize;
+import org.springframework.security.authentication.AuthenticationManager;
+
+@Configuration
+@EnableIntegration
+public class SecuredDirectChannel {
+
+    @Bean(name = "startDirectChannel")
+    @SecuredChannel(interceptor = "channelSecurityInterceptor", sendAccess = { "ROLE_VIEWER", "jane" })
+    public DirectChannel startDirectChannel() {
+        return new DirectChannel();
+    }
+
+    @ServiceActivator(inputChannel = "startDirectChannel", outputChannel = "endDirectChannel")
+    @PreAuthorize("hasRole('ROLE_LOGGER')")
+    public Message<?> logMessage(Message<?> message) {
+        Logger.getAnonymousLogger().info(message.toString());
+        return message;
+    }
+
+    @Bean(name = "endDirectChannel")
+    @SecuredChannel(interceptor = "channelSecurityInterceptor", sendAccess = { "ROLE_EDITOR" })
+    public DirectChannel endDirectChannel() {
+        return new DirectChannel();
+    }
+
+    @Autowired
+    @Bean
+    public ChannelSecurityInterceptor channelSecurityInterceptor(AuthenticationManager authenticationManager, AccessDecisionManager customAccessDecisionManager) {
+        ChannelSecurityInterceptor channelSecurityInterceptor = new ChannelSecurityInterceptor();
+        channelSecurityInterceptor.setAuthenticationManager(authenticationManager);
+        channelSecurityInterceptor.setAccessDecisionManager(customAccessDecisionManager);
+        return channelSecurityInterceptor;
+    }
+
+}

spring-integration/src/main/java/com/baeldung/si/security/SecurityConfig.java

@@ -0,0 +1,46 @@
+package com.baeldung.si.security;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.integration.security.channel.ChannelSecurityInterceptor;
+import org.springframework.security.access.AccessDecisionManager;
+import org.springframework.security.access.AccessDecisionVoter;
+import org.springframework.security.access.vote.AffirmativeBased;
+import org.springframework.security.access.vote.RoleVoter;
+import org.springframework.security.authentication.AuthenticationManager;
+import org.springframework.security.config.annotation.method.configuration.EnableGlobalMethodSecurity;
+import org.springframework.security.config.annotation.method.configuration.GlobalMethodSecurityConfiguration;
+
+@Configuration
+@EnableGlobalMethodSecurity(prePostEnabled = true)
+public class SecurityConfig extends GlobalMethodSecurityConfiguration {
+
+    @Override
+    @Bean
+    public AuthenticationManager authenticationManager() throws Exception {
+        return super.authenticationManager();
+    }
+
+    @Bean
+    public AccessDecisionManager customAccessDecisionManager() {
+        List<AccessDecisionVoter<? extends Object>> decisionVoters = new ArrayList<>();
+        decisionVoters.add(new RoleVoter());
+        decisionVoters.add(new UsernameAccessDecisionVoter());
+        AccessDecisionManager accessDecisionManager = new AffirmativeBased(decisionVoters);
+        return accessDecisionManager;
+    }
+
+    @Autowired
+    @Bean
+    public ChannelSecurityInterceptor channelSecurityInterceptor(AuthenticationManager authenticationManager, AccessDecisionManager customAccessDecisionManager) {
+        ChannelSecurityInterceptor channelSecurityInterceptor = new ChannelSecurityInterceptor();
+        channelSecurityInterceptor.setAuthenticationManager(authenticationManager);
+        channelSecurityInterceptor.setAccessDecisionManager(customAccessDecisionManager);
+        return channelSecurityInterceptor;
+    }
+
+}

spring-integration/src/main/java/com/baeldung/si/security/SecurityPubSubChannel.java

@@ -0,0 +1,82 @@
+package com.baeldung.si.security;
+
+import java.util.stream.Collectors;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.integration.annotation.ServiceActivator;
+import org.springframework.integration.channel.DirectChannel;
+import org.springframework.integration.channel.PublishSubscribeChannel;
+import org.springframework.integration.config.EnableIntegration;
+import org.springframework.integration.config.GlobalChannelInterceptor;
+import org.springframework.integration.security.channel.SecuredChannel;
+import org.springframework.integration.security.channel.SecurityContextPropagationChannelInterceptor;
+import org.springframework.integration.support.DefaultMessageBuilderFactory;
+import org.springframework.integration.support.MessageBuilder;
+import org.springframework.messaging.Message;
+import org.springframework.messaging.support.ChannelInterceptor;
+import org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor;
+import org.springframework.security.access.prepost.PreAuthorize;
+import org.springframework.security.core.context.SecurityContext;
+import org.springframework.security.core.context.SecurityContextHolder;
+
+@Configuration
+@EnableIntegration
+public class SecurityPubSubChannel {
+
+    @Bean(name = "startPSChannel")
+    @SecuredChannel(interceptor = "channelSecurityInterceptor", sendAccess = "ROLE_VIEWER")
+    public PublishSubscribeChannel startChannel() {
+        return new PublishSubscribeChannel(executor());
+    }
+
+    @ServiceActivator(inputChannel = "startPSChannel", outputChannel = "finalPSResult")
+    @PreAuthorize("hasRole('ROLE_LOGGER')")
+    public Message<?> changeMessageToRole(Message<?> message) {
+        return buildNewMessage(getRoles(), message);
+    }
+
+    @ServiceActivator(inputChannel = "startPSChannel", outputChannel = "finalPSResult")
+    @PreAuthorize("hasRole('ROLE_VIEWER')")
+    public Message<?> changeMessageToUserName(Message<?> message) {
+        return buildNewMessage(getUsername(), message);
+    }
+
+    @Bean(name = "finalPSResult")
+    public DirectChannel finalPSResult() {
+        return new DirectChannel();
+    }
+
+    @Bean
+    @GlobalChannelInterceptor(patterns = { "startPSChannel", "endDirectChannel" })
+    public ChannelInterceptor securityContextPropagationInterceptor() {
+        return new SecurityContextPropagationChannelInterceptor();
+    }
+
+    @Bean
+    public ThreadPoolTaskExecutor executor() {
+        ThreadPoolTaskExecutor pool = new ThreadPoolTaskExecutor();
+        pool.setCorePoolSize(10);
+        pool.setMaxPoolSize(10);
+        pool.setWaitForTasksToCompleteOnShutdown(true);
+        return pool;
+    }
+
+    public String getRoles() {
+        SecurityContext securityContext = SecurityContextHolder.getContext();
+        return securityContext.getAuthentication().getAuthorities().stream().map(auth -> auth.getAuthority()).collect(Collectors.joining(","));
+    }
+
+    public String getUsername() {
+        SecurityContext securityContext = SecurityContextHolder.getContext();
+        return securityContext.getAuthentication().getName();
+    }
+
+    public Message<String> buildNewMessage(String content, Message<?> message) {
+        DefaultMessageBuilderFactory builderFactory = new DefaultMessageBuilderFactory();
+        MessageBuilder<String> messageBuilder = builderFactory.withPayload(content);
+        messageBuilder.copyHeaders(message.getHeaders());
+        return messageBuilder.build();
+    }
+
+}

spring-integration/src/main/java/com/baeldung/si/security/UsernameAccessDecisionVoter.java

@@ -0,0 +1,45 @@
+package com.baeldung.si.security;
+
+import java.util.Collection;
+
+import org.springframework.security.access.AccessDecisionVoter;
+import org.springframework.security.access.ConfigAttribute;
+import org.springframework.security.core.Authentication;
+
+public class UsernameAccessDecisionVoter implements AccessDecisionVoter<Object> {
+    private String rolePrefix = "ROLE_";
+
+    @Override
+    public boolean supports(ConfigAttribute attribute) {
+        if ((attribute.getAttribute() != null)
+                && !attribute.getAttribute().startsWith(rolePrefix)) {
+            return true;
+        }else {
+            return false;
+        }
+    }
+
+    @Override
+    public boolean supports(Class<?> clazz) {
+        return true;
+    }
+
+    @Override
+    public int vote(Authentication authentication, Object object, Collection<ConfigAttribute> attributes) {
+        if (authentication == null) {
+            return ACCESS_DENIED;
+        }
+        String name = authentication.getName();
+        int result = ACCESS_ABSTAIN;
+        for (ConfigAttribute attribute : attributes) {
+            if (this.supports(attribute)) {
+                result = ACCESS_DENIED;
+                if (attribute.getAttribute().equals(name)) {
+                    return ACCESS_GRANTED;
+                }
+            }
+        }
+        return result;
+    }
+
+}

spring-integration/src/main/java/com/baeldung/subflows/discardflow/FilterExample.java

@@ -0,0 +1,57 @@
+package com.baeldung.subflows.discardflow;
+
+import java.util.Collection;
+import org.springframework.context.annotation.Bean;
+import org.springframework.integration.annotation.Gateway;
+import org.springframework.integration.annotation.IntegrationComponentScan;
+import org.springframework.integration.annotation.MessagingGateway;
+import org.springframework.integration.channel.QueueChannel;
+import org.springframework.integration.config.EnableIntegration;
+import org.springframework.integration.dsl.IntegrationFlow;
+
+@EnableIntegration
+@IntegrationComponentScan
+public class FilterExample {
+    @MessagingGateway
+    public interface NumbersClassifier {
+        @Gateway(requestChannel = "classify.input")
+        void classify(Collection<Integer> numbers);
+    }
+
+    @Bean
+    QueueChannel multipleofThreeChannel() {
+        return new QueueChannel();
+    }
+
+    @Bean
+    QueueChannel remainderIsOneChannel() {
+        return new QueueChannel();
+    }
+
+    @Bean
+    QueueChannel remainderIsTwoChannel() {
+        return new QueueChannel();
+    }
+    boolean isMultipleOfThree(Integer number) {
+        return number % 3 == 0;
+    }
+
+    boolean isRemainderOne(Integer number) {
+        return number % 3 == 1;
+    }
+
+    boolean isRemainderTwo(Integer number) {
+        return number % 3 == 2;
+    }
+    @Bean
+    public IntegrationFlow classify() {
+        return flow -> flow.split()
+            .<Integer> filter(this::isMultipleOfThree, notMultiple  -> notMultiple 
+                .discardFlow(oneflow  -> oneflow 
+                    .<Integer> filter(this::isRemainderOne, 
+                    twoflow  -> twoflow .discardChannel("remainderIsTwoChannel"))
+                .channel("remainderIsOneChannel")))
+            .channel("multipleofThreeChannel");
+    }
+
+}

spring-integration/src/main/java/com/baeldung/subflows/publishsubscribechannel/PublishSubscibeChannelExample.java

@@ -0,0 +1,60 @@
+package com.baeldung.subflows.publishsubscribechannel;
+
+import java.util.Collection;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.integration.annotation.Gateway;
+import org.springframework.integration.annotation.IntegrationComponentScan;
+import org.springframework.integration.annotation.MessagingGateway;
+
+import org.springframework.integration.channel.QueueChannel;
+import org.springframework.integration.config.EnableIntegration;
+import org.springframework.integration.dsl.IntegrationFlow;
+
+@EnableIntegration
+@IntegrationComponentScan
+public class PublishSubscibeChannelExample {
+    @MessagingGateway
+    public interface NumbersClassifier {
+        @Gateway(requestChannel = "classify.input")
+        void classify(Collection<Integer> numbers);
+    }
+
+    @Bean
+    QueueChannel multipleofThreeChannel() {
+        return new QueueChannel();
+    }
+
+    @Bean
+    QueueChannel remainderIsOneChannel() {
+        return new QueueChannel();
+    }
+
+    @Bean
+    QueueChannel remainderIsTwoChannel() {
+        return new QueueChannel();
+    }
+    boolean isMultipleOfThree(Integer number) {
+        return number % 3 == 0;
+    }
+
+    boolean isRemainderOne(Integer number) {
+        return number % 3 == 1;
+    }
+
+    boolean isRemainderTwo(Integer number) {
+        return number % 3 == 2;
+    }
+    @Bean
+    public IntegrationFlow classify() {
+        return flow -> flow.split()
+            .publishSubscribeChannel(subscription -> subscription.subscribe(subflow -> subflow.<Integer> filter(this::isMultipleOfThree)
+                .channel("multipleofThreeChannel"))
+                .subscribe(subflow -> subflow.<Integer> filter(this::isRemainderOne)
+                    .channel("remainderIsOneChannel"))
+                .subscribe(subflow -> subflow.<Integer> filter(this::isRemainderTwo)
+                    .channel("remainderIsTwoChannel")));
+    }
+    
+
+}

spring-integration/src/main/java/com/baeldung/subflows/routeToRecipients/RouteToRecipientsExample.java

@@ -0,0 +1,60 @@
+package com.baeldung.subflows.routetorecipients;
+
+import java.util.Collection;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.integration.annotation.Gateway;
+import org.springframework.integration.annotation.IntegrationComponentScan;
+import org.springframework.integration.annotation.MessagingGateway;
+import org.springframework.integration.channel.QueueChannel;
+import org.springframework.integration.config.EnableIntegration;
+import org.springframework.integration.dsl.IntegrationFlow;
+
+@EnableIntegration
+@IntegrationComponentScan
+public class RouteToRecipientsExample {
+    @MessagingGateway
+    public interface NumbersClassifier {
+        @Gateway(requestChannel = "classify.input")
+        void classify(Collection<Integer> numbers);
+    }
+
+    @Bean
+    QueueChannel multipleofThreeChannel() {
+        return new QueueChannel();
+    }
+
+    @Bean
+    QueueChannel remainderIsOneChannel() {
+        return new QueueChannel();
+    }
+
+    @Bean
+    QueueChannel remainderIsTwoChannel() {
+        return new QueueChannel();
+    }
+    boolean isMultipleOfThree(Integer number) {
+        return number % 3 == 0;
+    }
+
+    boolean isRemainderOne(Integer number) {
+        return number % 3 == 1;
+    }
+
+    boolean isRemainderTwo(Integer number) {
+        return number % 3 == 2;
+    }
+
+    @Bean
+    public IntegrationFlow classify() {
+        return flow -> flow.split()
+            .routeToRecipients(route -> route
+                .recipientFlow(subflow -> subflow
+                    .<Integer> filter(this::isMultipleOfThree)
+                    .channel("multipleofThreeChannel"))
+                .<Integer> recipient("remainderIsOneChannel",this::isRemainderOne)
+                .<Integer> recipient("remainderIsTwoChannel",this::isRemainderTwo));
+    }
+   
+
+}

spring-integration/src/main/java/com/baeldung/subflows/separateflows/SeparateFlowsExample.java

@@ -0,0 +1,77 @@
+package com.baeldung.subflows.separateflows;
+
+import java.util.Collection;
+
+import org.springframework.context.annotation.Bean;
+import org.springframework.integration.annotation.Gateway;
+import org.springframework.integration.annotation.IntegrationComponentScan;
+import org.springframework.integration.annotation.MessagingGateway;
+
+import org.springframework.integration.channel.QueueChannel;
+import org.springframework.integration.config.EnableIntegration;
+import org.springframework.integration.dsl.IntegrationFlow;
+
+@EnableIntegration
+@IntegrationComponentScan
+public class SeparateFlowsExample {
+    @MessagingGateway
+    public interface NumbersClassifier {
+        @Gateway(requestChannel = "multipleOfThreeFlow.input")
+        void multipleofThree(Collection<Integer> numbers);
+
+        @Gateway(requestChannel = "remainderIsOneFlow.input")
+        void remainderIsOne(Collection<Integer> numbers);
+
+        @Gateway(requestChannel = "remainderIsTwoFlow.input")
+        void remainderIsTwo(Collection<Integer> numbers);
+    }
+    
+    @Bean
+    QueueChannel multipleOfThreeChannel() {
+        return new QueueChannel();
+    }
+ 
+    @Bean
+    QueueChannel remainderIsOneChannel() {
+        return new QueueChannel();
+    }
+ 
+    @Bean
+    QueueChannel remainderIsTwoChannel() {
+        return new QueueChannel();
+    }
+
+    boolean isMultipleOfThree(Integer number) {
+        return number % 3 == 0;
+    }
+
+    boolean isRemainderOne(Integer number) {
+        return number % 3 == 1;
+    }
+
+    boolean isRemainderTwo(Integer number) {
+        return number % 3 == 2;
+    }
+
+    @Bean
+    public IntegrationFlow multipleOfThreeFlow() {
+        return flow -> flow.split()
+            .<Integer> filter(this::isMultipleOfThree)
+            .channel("multipleOfThreeChannel");
+    }
+
+    @Bean
+    public IntegrationFlow remainderIsOneFlow() {
+        return flow -> flow.split()
+            .<Integer> filter(this::isRemainderOne)
+            .channel("remainderIsOneChannel");
+    }
+
+    @Bean
+    public IntegrationFlow remainderIsTwoFlow() {
+        return flow -> flow.split()
+            .<Integer> filter(this::isRemainderTwo)
+            .channel("remainderIsTwoChannel");
+    }
+
+}

spring-integration/src/main/java/com/baeldung/subflows/subflowmapping/RouterExample.java

@@ -0,0 +1,62 @@
+package com.baeldung.subflows.subflowmapping;
+
+import java.util.Collection;
+import org.springframework.context.annotation.Bean;
+import org.springframework.integration.annotation.Gateway;
+import org.springframework.integration.annotation.IntegrationComponentScan;
+import org.springframework.integration.annotation.MessagingGateway;
+import org.springframework.integration.channel.QueueChannel;
+import org.springframework.integration.config.EnableIntegration;
+import org.springframework.integration.dsl.IntegrationFlow;
+
+@EnableIntegration
+@IntegrationComponentScan
+public class RouterExample {
+    @MessagingGateway
+    public interface NumbersClassifier {
+        @Gateway(requestChannel = "classify.input")
+        void classify(Collection<Integer> numbers);
+    }
+
+    @Bean
+    QueueChannel multipleofThreeChannel() {
+        return new QueueChannel();
+    }
+
+    @Bean
+    QueueChannel remainderIsOneChannel() {
+        return new QueueChannel();
+    }
+
+    @Bean
+    QueueChannel remainderIsTwoChannel() {
+        return new QueueChannel();
+    }
+
+    boolean isMultipleOfThree(Integer number) {
+        return number % 3 == 0;
+    }
+
+    boolean isRemainderOne(Integer number) {
+        return number % 3 == 1;
+    }
+
+    boolean isRemainderTwo(Integer number) {
+        return number % 3 == 2;
+    }
+
+    @Bean
+    public IntegrationFlow classify() {
+        return flow -> flow.split()
+            .<Integer, Integer> route(number -> number % 3, 
+                mapping -> mapping
+                  .channelMapping(0, "multipleofThreeChannel")
+                  .subFlowMapping(1, subflow -> subflow.channel("remainderIsOneChannel"))
+                  .subFlowMapping(2, subflow -> subflow
+                      .<Integer> handle((payload, headers) -> {
+                          // do extra work on the payload
+                         return payload;
+                      }))).channel("remainderIsTwoChannel");
+    }
+
+}

spring-integration/src/main/java/com/baeldung/tx/ServiceActivator.java

@@ -0,0 +1,27 @@
+package com.baeldung.tx;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.jdbc.core.JdbcTemplate;
+
+public class ServiceActivator {
+
+    @Autowired
+    private JdbcTemplate jdbcTemplate;
+
+    private final Logger log = LoggerFactory.getLogger(this.getClass());
+
+    public void checkTestResults(String payload) {
+
+        this.jdbcTemplate.update("insert into STUDENT values(?)", payload);
+
+        if (payload.toLowerCase().startsWith("fail")) {
+            log.error("Service failure. Test result: {}", payload);
+            throw new RuntimeException("Service failure.");
+        }
+
+        log.info("Service success. Test result: {}", payload);
+    }
+
+}

spring-integration/src/main/java/com/baeldung/tx/TxIntegrationConfig.java

@@ -0,0 +1,155 @@
+package com.baeldung.tx;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.context.annotation.AnnotationConfigApplicationContext;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+import org.springframework.context.support.AbstractApplicationContext;
+import org.springframework.expression.spel.standard.SpelExpressionParser;
+import org.springframework.integration.annotation.InboundChannelAdapter;
+import org.springframework.integration.annotation.Poller;
+import org.springframework.integration.annotation.ServiceActivator;
+import org.springframework.integration.annotation.Transformer;
+import org.springframework.integration.channel.DirectChannel;
+import org.springframework.integration.config.EnableIntegration;
+import org.springframework.integration.core.MessageSource;
+import org.springframework.integration.dsl.Pollers;
+import org.springframework.integration.file.FileReadingMessageSource;
+import org.springframework.integration.file.filters.SimplePatternFileListFilter;
+import org.springframework.integration.file.transformer.FileToStringTransformer;
+import org.springframework.integration.scheduling.PollerMetadata;
+import org.springframework.integration.transaction.*;
+import org.springframework.jdbc.core.JdbcTemplate;
+import org.springframework.jdbc.datasource.DataSourceTransactionManager;
+import org.springframework.jdbc.datasource.embedded.EmbeddedDatabaseBuilder;
+import org.springframework.jdbc.datasource.embedded.EmbeddedDatabaseType;
+import org.springframework.messaging.MessageChannel;
+import org.springframework.transaction.interceptor.TransactionInterceptor;
+
+import javax.sql.DataSource;
+import java.io.File;
+import java.util.Scanner;
+
+@Configuration
+@EnableIntegration
+public class TxIntegrationConfig {
+
+    private final Logger log = LoggerFactory.getLogger(this.getClass());
+
+    public final String INPUT_DIR = System.getProperty("java.io.tmpdir") + "/tx/";
+    public final String FILE_PATTERN = "*.txt";
+
+    @Autowired
+    private JdbcTemplate jdbcTemplate;
+
+    @Autowired
+    private DataSource dataSource;
+
+    @Autowired
+    private TransactionSynchronizationFactory transactionSynchronizationFactory;
+
+    @Autowired
+    DataSourceTransactionManager txManager;
+
+    @Bean
+    public MessageChannel inputChannel() {
+        return new DirectChannel();
+    }
+
+    @Bean
+    @InboundChannelAdapter(value = "inputChannel", poller = @Poller(value = "pollerMetadata"))
+    public MessageSource<File> fileReadingMessageSource() {
+        FileReadingMessageSource sourceReader = new FileReadingMessageSource();
+        sourceReader.setDirectory(new File(INPUT_DIR));
+        sourceReader.setFilter(new SimplePatternFileListFilter(FILE_PATTERN));
+        return sourceReader;
+    }
+
+    @Bean
+    public PollerMetadata pollerMetadata() {
+        return Pollers.fixedDelay(5000)
+                 .advice(transactionInterceptor())
+                 .transactionSynchronizationFactory(transactionSynchronizationFactory)
+                 .get();
+    }
+
+    private TransactionInterceptor transactionInterceptor() {
+        return new TransactionInterceptorBuilder().transactionManager(txManager).build();
+    }
+
+    @Bean
+    public TransactionSynchronizationFactory transactionSynchronizationFactory() {
+        ExpressionEvaluatingTransactionSynchronizationProcessor processor =
+            new ExpressionEvaluatingTransactionSynchronizationProcessor();
+
+        SpelExpressionParser spelParser = new SpelExpressionParser();
+        processor.setAfterCommitExpression(
+            spelParser.parseExpression(
+                "payload.renameTo(new java.io.File(payload.absolutePath + '.PASSED'))"));
+        processor.setAfterRollbackExpression(
+            spelParser.parseExpression(
+                "payload.renameTo(new java.io.File(payload.absolutePath + '.FAILED'))"));
+
+        return new DefaultTransactionSynchronizationFactory(processor);
+        }
+
+    @Bean
+    @Transformer(inputChannel = "inputChannel", outputChannel = "toServiceChannel")
+    public FileToStringTransformer fileToStringTransformer() {
+        return new FileToStringTransformer();
+    }
+
+    @ServiceActivator(inputChannel = "toServiceChannel")
+    public void serviceActivator(String payload) {
+
+        jdbcTemplate.update("insert into STUDENT values(?)", payload);
+
+        if (payload.toLowerCase().startsWith("fail")) {
+            log.error("Service failure. Test result: {} ", payload);
+            throw new RuntimeException("Service failure.");
+        }
+
+        log.info("Service success. Test result: {}", payload);
+    }
+
+    @Bean
+    public JdbcTemplate jdbcTemplate(DataSource dataSource) {
+        return new JdbcTemplate(dataSource);
+    }
+
+    @Bean
+    public DataSource dataSource() {
+        return new EmbeddedDatabaseBuilder()
+                .setType(EmbeddedDatabaseType.H2)
+                .addScript("classpath:table.sql")
+                .build();
+    }
+
+    @Bean
+    public DataSourceTransactionManager txManager() {
+        return new DataSourceTransactionManager(dataSource);
+    }
+
+    public static void main(final String... args) {
+        final AbstractApplicationContext context = new AnnotationConfigApplicationContext(TxIntegrationConfig.class);
+        context.registerShutdownHook();
+
+        final Scanner scanner = new Scanner(System.in);
+        System.out.print("Integration flow is running. Type q + <enter> to quit ");
+        while (true) {
+            final String input = scanner.nextLine();
+            if ("q".equals(input.trim())) {
+                context.close();
+                scanner.close();
+                break;
+            }
+        }
+        System.exit(0);
+    }
+
+}
+    
+
+