[[Message-History]]
= Message History

Camel supports the
https://www.enterpriseintegrationpatterns.com/patterns/messaging/MessageHistory.html[Message History]
from the xref:enterprise-integration-patterns.adoc[EIP patterns] book.

The Message History from the EIP patterns allows for analyzing and debugging the flow of messages in a loosely coupled system.

image::eip/MessageHistory.gif[image]

Attaching a Message History to the message will provide a list of all applications that the message passed through since its origination.

During routing Camel captures how the Exchange is routed, as a `org.apache.camel.MessageHistory` entity
that is stored on the Exchange. On the `org.apache.camel.MessageHistory` there is information abut the
route id, processor id, timestamp, and elapsed time it took to process the Exchange by the processor.

== Enabling or disabling Message History

The Message History can be enabled or disabled per CamelContext or per route (enabled by default).
For example you can turn it off with

[source,java]
----
camelContext.setMessageHistory(false);
----

Or in XML

[source,xml]
----
<camelContext messageHistory="false">

</camelContext>
----

You can also do this per route. Then a route level configuration overrides the CamelContext level configuration.

== Route stack-trace in exceptions logged by error handler

If Message History is enabled, then Camel will leverage this information,
when the Error Handler logs exhausted exceptions. Then in addition to the caused exception with its stacktrace,
you can see the message history; you may think this as a "route stacktrace".

And example is provided below:

[source,text]
----
2013-05-31 14:41:28,084 [ - seda://start] ERROR DefaultErrorHandler            - Failed delivery for (MessageId: ID-davsclaus-air-lan-55446-1370004087263-0-1 on ExchangeId: ID-davsclaus-air-lan-55446-1370004087263-0-3). Exhausted after delivery attempt: 1 caught: java.lang.IllegalArgumentException: Forced to dump message history

Message History
---------------------------------------------------------------------------------------------------------------------------------------
RouteId              ProcessorId          Processor                                                                        Elapsed (ms)
[route1            ] [to1               ] [log:foo                                                                       ] [         6]
[route1            ] [to2               ] [direct:bar                                                                    ] [       102]
[route2            ] [to5               ] [log:bar                                                                       ] [         1]
[route2            ] [delay2            ] [delay[{100}]                                                                  ] [       100]
[route2            ] [to6               ] [mock:bar                                                                      ] [         0]
[route1            ] [delay1            ] [delay[{300}]                                                                  ] [       303]
[route1            ] [to3               ] [log:baz                                                                       ] [         0]
[route1            ] [process1          ] [org.apache.camel.processor.MessageHistoryDumpRoutingTest$1$1@6a53f9d8         ] [         2]

Stacktrace
---------------------------------------------------------------------------------------------------------------------------------------
java.lang.IllegalArgumentException: Forced to dump message history
    at org.apache.camel.processor.MessageHistoryDumpRoutingTest$1$1.process(MessageHistoryDumpRoutingTest.java:54)
    at org.apache.camel.processor.DelegateSyncProcessor.process(DelegateSyncProcessor.java:63)
    at org.apache.camel.processor.RedeliveryErrorHandler.process(RedeliveryErrorHandler.java:388)
    at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:189)
    at org.apache.camel.processor.Pipeline.process(Pipeline.java:118)
    at org.apache.camel.processor.Pipeline.process(Pipeline.java:80)
    at org.apache.camel.processor.DelayProcessorSupport.process(DelayProcessorSupport.java:117)
    at org.apache.camel.processor.RedeliveryErrorHandler.process(RedeliveryErrorHandler.java:388)
    at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:189)
    at org.apache.camel.processor.Pipeline.process(Pipeline.java:118)
    at org.apache.camel.processor.Pipeline.process(Pipeline.java:80)
    at org.apache.camel.processor.CamelInternalProcessor.process(CamelInternalProcessor.java:189)
    at org.apache.camel.component.seda.SedaConsumer.sendToConsumers(SedaConsumer.java:293)
    at org.apache.camel.component.seda.SedaConsumer.doRun(SedaConsumer.java:202)
    at org.apache.camel.component.seda.SedaConsumer.run(SedaConsumer.java:149)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:722)
----

You can turn off logging message history from the Error Handler using

[source,java]
----
errorHandler(defaultErrorHandler().logExhaustedMessageHistory(false));
----

From Camel 2.17 onwards the Error Handler do not log the message body/header details anymore (to avoid logging sensitive message body details).
You can turn on the old behavior.

[source,java]
----
errorHandler(defaultErrorHandler().logExhaustedMessageBody(true));
----