All at sea with Spring Batch Integration

[trionic]

Greetings fellow batchonauts

I am writing software to propagate changes to user accounts across several different external systems. I have used Spring Integration to acquire user data from a source system, resolve user account metadata and create a Message containing all the data required to batch update a specific external system. At that point it's over to Spring Batch.

The messages that emerge from Integration come from a custom message splitter. The message header is the name of the target external system and the payload is a Collection of beans. The splitter returns this:

Collection<Message<List<UserUpdateBean>>>

Using this code:

Collection<Message<List<UserUpdateBean>>> messages = new ArrayList<Message<List<UserUpdateBean>>>();

MessageBuilder<List<UserUpdateBean>> messageBuilder = MessageBuilder.withPayload(messagePayload);
messageBuilder.setHeader(MessageHeaderNames.RECIPIENT.name(), recipientHeaderValue);

Message<List<UserUpdateBean>> message = messageBuilder.build();
messages.add(message);

Where the user bean looks like this:

public class UserUpdateBean {
   private String userID;
   private boolean isNewUser;
   private String userName;
   private String screenName;
   private String firstName;
   private String middleName;
   private String lastName;
   private Date birthday;
   private Long employeeNumber;
   private String emailAddress;
   private String jobTitle;
   private String jobClass;
   private String greeting;

   ...
}

A custom message router sends a Message<List<UserUpdateBean>> to a specific channel based on the header value. The header value contains the name of the target system.. The channel is used only for updates for a specific external system.

<si:header-value-router input-channel="outboundUserUpdateRoutingChannel" header-name="${message.header.name.recipient}">
	<si:mapping value="${message.header.value.loginmanagement}" channel="outboundLoginManagementUserUpdateChannel" />
	<si:mapping value="${message.header.value.arvalonline}" channel="outboundArvalOnlineUserUpdateChannel" />
	<si:mapping value="${message.header.value.card}" channel="outboundCardUserUpdateChannel" />
	<si:mapping value="${message.header.value.drive}" channel="outboundDriveUserUpdateChannel" />
</si:header-value-router>

This is what I am aiming for:

1. Batch receives a Message<List<UserUpdateBean>>
2. An ItemReader implementation gets the message payload (List<UserUpdateBean>) and chunk-reads the UserUpdateBeans from the List
3. An ItemProcessor implementation does some further processing (optional step)
4. An ItemWriter implementation puts values from each UserUpdateBean in the chunk into a SQL batch update statement and executes it

This is my (incomplete) Batch configuration:

@Bean
public JobLaunchingMessageHandler jobLaunchingMessageHandler() {
	JobLaunchingMessageHandler jobLaunchingMessageHandler = new JobLaunchingMessageHandler(this.jobLauncher);
	return jobLaunchingMessageHandler;
}

<bean id="jobRegistry" class="org.springframework.batch.core.configuration.support.MapJobRegistry" />
<bean id="jobLauncher" class="org.springframework.batch.core.launch.support.SimpleJobLauncher">
	<property name="jobRepository" ref="jobRepository" />
</bean>
<bean id="jobRegistryBeanPostProcessor" class="org.springframework.batch.core.configuration.support.JobRegistryBeanPostProcessor">
	<property name="jobRegistry" ref="jobRegistry" />
</bean>
<bean id="jobRepository" class="org.springframework.batch.core.repository.support.JobRepositoryFactoryBean">
	<property name="dataSource" ref="ulmDataSource" />
	<property name="transactionManager" ref="ulmDataSourceTransactionManager" />
</bean>

<si:service-activator input-channel="outboundLoginManagementUserBatchUpdateChannel" output-channel="loginManagementUserUpdateStatusChannel" ref="jobLaunchingMessageHandler" />

The problem is that I just cannot see how to link Integration and Batch together using Batch Integration.

The message arrives in JobLaunchingMessageHandler service activator. Then what? I don't know where the message ends up or how to the message's payload into the ItemReader. The message seems to disappear into a black hole.

I have scoured Google and read the Batch manual plus other documentation a hundred times but I can't make sense of it. I am completely stuck.