Changing apache camel message type to InOut - apache-camel

Question

From what I understand, an InOut message is one where a response can be received from the destination.
However, I have not been able to find any example of how to convert a message to InOut type, and how to access the response from the destination
For example, given a route like:
from("direct:start").to("smtps://smtp.gmail.com:465?username=user#gmail.com&password=usrpw&to=address#gmail.com")
How to convert the message routed to smtps component into InOut type?
Can I expect a response from the smtp component, e.g. indicating that the message was sent successfully?
how to access this response?

Answer 1

By default, each ".to(uri)" are in InOut. The body in the next step will be replaced by the response of the InOut destination. For example, in HTTP component, if you have the following route :
from(direct:start)
.to(http://...)
.log(INFO, "${body}")
The response to the http call will be logged.
If you don't find good informations in the document, I highly recommend you to check the code of the related producer to know what's returned or can be used.
https://github.com/apache/camel
For example, for SMTP, I haven't found the doc saying what's happening to the body, but the code is pretty much clear :
public void process(final Exchange exchange) {
ClassLoader tccl = Thread.currentThread().getContextClassLoader();
try {
ClassLoader applicationClassLoader = getEndpoint().getCamelContext().getApplicationContextClassLoader();
if (applicationClassLoader != null) {
Thread.currentThread().setContextClassLoader(applicationClassLoader);
}
MimeMessage mimeMessage;
final Object body = exchange.getIn().getBody();
if (body instanceof MimeMessage) {
// Body is directly a MimeMessage
mimeMessage = (MimeMessage) body;
} else {
// Create a message with exchange data
mimeMessage = new MimeMessage(sender.getSession());
getEndpoint().getBinding().populateMailMessage(getEndpoint(), mimeMessage, exchange);
}
if (LOG.isDebugEnabled()) {
LOG.debug("Sending MimeMessage: {}", MailUtils.dumpMessage(mimeMessage));
}
sender.send(mimeMessage);
// set the message ID for further processing
exchange.getIn().setHeader(MailConstants.MAIL_MESSAGE_ID, mimeMessage.getMessageID());
} catch (MessagingException e) {
exchange.setException(e);
} catch (IOException e) {
exchange.setException(e);
} finally {
Thread.currentThread().setContextClassLoader(tccl);
}
}
Your exchange will have an header with the MAIL_ID ("CamelMailMessageId"), and in case of any messaging exception, the exception will be propagated. The body seems to be left untouched, even if it's InOut.