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Tracer

Tracer is the sister to Camel's Debugger. They are much alike.
Camel supports a tracer interceptor that is used for logging the route executions at INFO level.

The Tracer is an InterceptStrategy which can be applied to a DefaultCamelContext or SpringCamelContext to ensure that there is a TracerInterceptor created for every node in the DSL.

Formatting

The tracer formats the execution of exchanges to log lines. They are logged at INFO level in the log category: org.apache.camel.processor.interceptor.TraceInterceptor.
The tracer uses by default TraceFormatter to format the log line.

TraceFormatter has the following options

Option

Default

Description

showBreadCrumb

true

Outputs the unique unit of work for the exchange. To be used for correlation so you can identify the same exchange.

showNode

true

The destination node.

showExchangeId

false

To output the unique exchange id. Currently the breadcrumb is sufficient.

showProperties

true

Output the exchange properties

showHeaders

true

Output the in message headers

showBodyType

true

Output the in body Java type

showBody

true

Output the in body

Example:

ID-claus-acer/3690-1214458315718/2-0 -> node3 To[mock:a] InOnly Properties:{CamelCauseException=null} Headers:{to=James} Body:Hello London

ID-claus-acer/3690-1214458315718/2-0 is the breadcrumb with the unique correlation id.
node3 is the id of the node in the route path. Is always shown.
Toa is the destination node.
InOnly is the exchange pattern. Is always shown.
Then the rest is properties, headers and the body.

Enabling

To enable tracer from the main run

java org.apache.camel.spring.Main -t

or 

java org.apache.camel.spring.Main -trace

and the tracer will be active.

Enabling from Java DSL

The tracer can be enabled by adding it to the interceptor chain to the camel context. This is demonstrated in the unit test below.
Notice: We could have changed the properties on the Tracer object before adding it, if we e.g. don't like the default settings.

Error formatting macro: snippet: java.lang.NullPointerException

Running the test we get the trace information logged at INFO level:

2008-06-26 07:31:55,828 [main           ] INFO  TraceInterceptor               - ID-claus-acer/3690-1214458315718/2-0 -> node5 Interceptor[Delegate(Pipeline[DeadLetterChannel[Delegate(TraceInterceptor[Processor[MyProcessor]]), RecipientList[log:org.apache.camel.DeadLetterChannel?level=error], RedeliveryPolicy[maximumRedeliveries=6]], DeadLetterChannel[Delegate(TraceInterceptor[To[mock:a]]), RecipientList[log:org.apache.camel.DeadLetterChannel?level=error], RedeliveryPolicy[maximumRedeliveries=6]], DeadLetterChannel[Delegate(TraceInterceptor[To[mock:b]]), RecipientList[log:org.apache.camel.DeadLetterChannel?level=error], RedeliveryPolicy[maximumRedeliveries=6]]])] InOnly Properties:{} Headers:{to=James} Body:Hello London
2008-06-26 07:31:55,843 [main           ] INFO  TraceInterceptor               - ID-claus-acer/3690-1214458315718/2-0 -> node2 Processor[MyProcessor] InOnly Properties:{CamelCauseException=null} Headers:{to=James} Body:Hello London
2008-06-26 07:31:55,843 [main           ] INFO  TraceInterceptor               - ID-claus-acer/3690-1214458315718/2-0 -> node3 To[mock:a] InOnly Properties:{CamelCauseException=null} Headers:{to=James} Body:Hello London
2008-06-26 07:31:55,843 [main           ] INFO  TraceInterceptor               - ID-claus-acer/3690-1214458315718/2-0 -> node4 To[mock:b] InOnly Properties:{CamelCauseException=null} Headers:{to=James} Body:Hello London
2008-06-26 07:31:55,859 [main           ] INFO  TraceInterceptor               - ID-claus-acer/3690-1214458315718/2-1 -> node5 Interceptor[Delegate(Pipeline[DeadLetterChannel[Delegate(TraceInterceptor[Processor[MyProcessor]]), RecipientList[log:org.apache.camel.DeadLetterChannel?level=error], RedeliveryPolicy[maximumRedeliveries=6]], DeadLetterChannel[Delegate(TraceInterceptor[To[mock:a]]), RecipientList[log:org.apache.camel.DeadLetterChannel?level=error], RedeliveryPolicy[maximumRedeliveries=6]], DeadLetterChannel[Delegate(TraceInterceptor[To[mock:b]]), RecipientList[log:org.apache.camel.DeadLetterChannel?level=error], RedeliveryPolicy[maximumRedeliveries=6]]])] InOnly Properties:{} Headers:{from=Claus} Body:This is Copenhagen calling
2008-06-26 07:31:55,859 [main           ] INFO  TraceInterceptor               - ID-claus-acer/3690-1214458315718/2-1 -> node2 Processor[MyProcessor] InOnly Properties:{CamelCauseException=null} Headers:{from=Claus} Body:This is Copenhagen calling
2008-06-26 07:31:55,875 [main           ] INFO  TraceInterceptor               - ID-claus-acer/3690-1214458315718/2-1 -> node3 To[mock:a] InOnly Properties:{CamelCauseException=null} Headers:{from=Claus} Body:This is Copenhagen calling
2008-06-26 07:31:55,875 [main           ] INFO  TraceInterceptor               - ID-claus-acer/3690-1214458315718/2-1 -> node4 To[mock:b] InOnly Properties:{CamelCauseException=null} Headers:{from=Claus} Body:This is Copenhagen calling

Enabling from Spring XML

TODO: Spring XML

See Also

See Debugger

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