Retain some information in payload with claim check pattern?

java, spring, spring-integration

Solution

The main purpose of `Claim Check` is to store the message and not have to worry about its size as the message might travel though several external systems. It can also be restored after system failure.

The best example from the real world is flight luggage. During transfers, you have in hand only the receipt and get the luggage at the end.

To achieve your goal I suggest you use `<enricher>`:

<int:enricher request-channel="claimCheckInChannel">
   <int:header name="claimCheck" expression="payload"/>
</int:enricher>

<claim-check-in input-channel="claimCheckInChannel" message-store="messageStore"/>

With that you don't lose the original `payload` and have the Claim Check `id` in the headers.

Note: Claim Check stores the entire `message` with headers, not only the `payload`. The relevant code is from `org.springframework.integration.transformer.ClaimCheckInTransformer`:

@Override
protected Object doTransform(Message<?> message) throws Exception {
    Assert.notNull(message, "message must not be null");
    Object payload = message.getPayload();
    Assert.notNull(payload, "payload must not be null");
    Message<?> storedMessage = this.messageStore.addMessage(message);
    MessageBuilder<?> responseBuilder = MessageBuilder.withPayload(storedMessage.getHeaders().getId());
    // headers on the 'current' message take precedence
    responseBuilder.copyHeaders(message.getHeaders());
    return responseBuilder.build();
}

Problem

I'm reading about the Claim Check pattern in Spring Integration. When using this pattern, it sounds as though the entire payload is placed in the message store and the resulting payload is only the claim check id. Does Spring provide a simple way to store the payload in the message store while at the same time retaining specific parts of the payload? Would you need to use a header enricher first and store the properties you want access to in the header? For example, say my payload is a simple XML document: ``` <payload> <cc>1234432156788765</cc> <or>5799</or> </payload> ``` I want to claim check this payload but still retain access to the `payload.or` element. How could this be done using current Spring Integration components?

Original source