springintegration handle message with messagid between three channels

In Spring Integration, handling a message across multiple channels while preserving a messageId (or similar identifier) can be achieved by leveraging message routing, channels, and custom message headers. Here’s how you can route and process messages between three channels while tracking a messageId through the flow.

Problem:
A message needs to be routed through three different channels.
A custom messageId (or similar identifier) is used to track the message through these channels.
Each channel can process the message and may modify it before sending it to the next channel.
Solution:
Here’s an example of how to handle this scenario using Spring Integration. The idea is to:

Use Spring Integration channels to move the message between processing stages.
Ensure the message contains a messageId in its headers to track it.
Steps:
Define the Channels: We define three channels: channel1, channel2, and channel3, where the message will be routed through.

Message Processing Flow: The message is sent to channel1, processed, routed to channel2, and finally routed to channel3.

Preserving the Message ID: We use Spring Integration headers (specifically messageHeaders) to store and pass the messageId between channels. If your messageId is custom, you can store it in the headers.

Example Configuration using Java DSL:

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.dsl.IntegrationFlow;
import org.springframework.integration.dsl.IntegrationFlows;
import org.springframework.messaging.Message;
import org.springframework.messaging.MessageChannel;
import org.springframework.messaging.MessageHeaders;
import org.springframework.messaging.support.MessageBuilder;

@Configuration
public class MessageFlowConfig {

// Define three channels
@Bean
public MessageChannel channel1() {
    return new DirectChannel();
}

@Bean
public MessageChannel channel2() {
    return new DirectChannel();
}

@Bean
public MessageChannel channel3() {
    return new DirectChannel();
}

// Flow starting from channel1
@Bean
public IntegrationFlow messageFlow() {
    return IntegrationFlows
            .from("channel1")
            .handle(this::processInChannel1)
            .channel("channel2")
            .handle(this::processInChannel2)
            .channel("channel3")
            .handle(this::processInChannel3)
            .get();
}

// Processor for channel 1
@ServiceActivator(inputChannel = "channel1")
public Message<?> processInChannel1(Message<?> message) {
    System.out.println("Processing in channel 1 with messageId: " + message.getHeaders().get("messageId"));
    // Add or modify the message, if needed
    return MessageBuilder.withPayload(message.getPayload())
                         .copyHeaders(message.getHeaders())
                         .build();
}

// Processor for channel 2
@ServiceActivator(inputChannel = "channel2")
public Message<?> processInChannel2(Message<?> message) {
    System.out.println("Processing in channel 2 with messageId: " + message.getHeaders().get("messageId"));
    // Add or modify the message, if needed
    return MessageBuilder.withPayload(message.getPayload())
                         .copyHeaders(message.getHeaders())
                         .build();
}

// Processor for channel 3
@ServiceActivator(inputChannel = "channel3")
public Message<?> processInChannel3(Message<?> message) {
    System.out.println("Processing in channel 3 with messageId: " + message.getHeaders().get("messageId"));
    // Add or modify the message, if needed
    return MessageBuilder.withPayload(message.getPayload())
                         .copyHeaders(message.getHeaders())
                         .build();
}

// Sending a test message to the first channel
@Bean
public IntegrationFlow startFlow() {
    return f -> f
            .handle(m -> {
                // Create a message with a custom messageId and send to channel1
                Message<String> message = MessageBuilder.withPayload("Test Message")
                        .setHeader("messageId", "12345")
                        .build();
                channel1().send(message);
            });
}

}
Key Points:
Channels: We define three DirectChannel beans (channel1, channel2, channel3) to represent the channels through which the message flows.
Message Flow: The messageFlow bean defines the flow, starting from channel1, routing to channel2, and then to channel3. The message is processed at each stage by the respective processInChannelX method.
Message Header: We use the MessageBuilder to build messages and maintain the messageId (or any other custom header) across different channels. This ensures the messageId is preserved as the message moves between channels.
Custom Logic: Each handle method can include custom business logic for processing the message at each stage.
Example Output:
When the message is processed across three channels, you might see output like this in the console:

Processing in channel 1 with messageId: 12345
Processing in channel 2 with messageId: 12345
Processing in channel 3 with messageId: 12345
Explanation:
The message starts at channel1 with a messageId of 12345.
It moves through channel2 and channel3, while the messageId is preserved across the channels.
Each step of the process can be customized based on your business logic or transformation needs.
This setup allows you to route messages between multiple channels while keeping track of the messageId across the entire flow.