How can I log processing a Message?

Camel provides many ways to log processing a message. Here is just some examples:

  • You can use the Log component which logs the Message content.
  • You can use the Tracer which trace logs message flow.
  • You can also use a Processor or Bean and log from Java code.
  • You can use the log DSL.

Using log DSL

And in Camel 2.2 you can use the log DSL which allows you to use Simple language to construct a dynamic message which gets logged.
For example you can do

from("direct:start").log("Processing ${id}").to("bean:foo");

Which will construct a String message at runtime using the Simple language. The log message will by logged at INFO level using the route id as the log name. By default a route is named route-1, route-2 etc. But you can use the routeId("myCoolRoute") to set a route name of choice.

Difference between log in the DSL and Log component
The log DSL is much lighter and meant for logging human logs such as Starting to do ... etc. It can only log a message based on the Simple language. On the other hand Log component is a full fledged component which involves using endpoints and etc. The Log component is meant for logging the Message itself and you have many URI options to control what you would like to be logged.

The log DSL have overloaded methods to set the logging level and/or name as well.

from("direct:start").log(LoggingLevel.DEBUG, "Processing ${id}").to("bean:foo");

For example you can use this to log the file name being processed if you consume files.

from("file://target/files").log(LoggingLevel.DEBUG, "Processing file ${file:name}").to("bean:foo");

Using log DSL from Spring

In Spring DSL its also easy to use log DSL as shown below:

        <route id="foo">
            <from uri="direct:foo"/>
            <log message="Got ${body}"/>
            <to uri="mock:foo"/>

The log tag has attributes to set the message, loggingLevel and logName. For example:

        <route id="baz">
            <from uri="direct:baz"/>
            <log message="Me Got ${body}" loggingLevel="FATAL" logName="cool"/>
            <to uri="mock:baz"/>

Using slf4j Marker

Available as of Camel 2.9

You can specify a marker name in the DSL

        <route id="baz">
            <from uri="direct:baz"/>
            <log message="Me Got ${body}" loggingLevel="FATAL" logName="cool" marker="myMarker"/>
            <to uri="mock:baz"/>

Using This Pattern

If you would like to use this EIP Pattern then please read the Getting Started, you may also find the Architecture useful particularly the description of Endpoint and URIs. Then you could try out some of the Examples first before trying this pattern out.

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