Log Component

The log: component logs message exchanges to the underlying logging mechanism.

Camel 2.7 or better uses sfl4j which allows you to configure logging via, among others:

• Log4j
• Logback
• JDK Util Logging logging

Camel 2.6 or lower uses commons-logging which allows you to configure logging via, among others:

• Log4j
• JDK Util Logging logging
• SimpleLog - a simple provider in commons-logging

Refer to the commons-logging user guide for a more complete overview of how to use and configure commons-logging.

URI format

log:loggingCategory[?options]

Where loggingCategory is the name of the logging category to use. You can append query options to the URI in the following format, ?option=value&option=value&...

For example, a log endpoint typically specifies the logging level using the level option, as follows:

log:org.apache.camel.example?level=DEBUG

The default logger logs every exchange (regular logging). But Camel also ships with the Throughput logger, which is used whenever the groupSize option is specified.

Also a log in the DSL In Camel 2.2 onwards there is a log directly in the DSL, but it has a different purpose. Its meant for lightweight and human logs. See more details at LogEIP.

Options

note: groupDelay and groupActiveOnly are only applicable when using groupInterval

Formatting

The log formats the execution of exchanges to log lines.
By default, the log uses LogFormatter to format the log output, where LogFormatter has the following options:

Logging stream bodies For older versions of Camel that do not support the showFiles or showStreams properties above, you can set the following property instead on the CamelContext to log both stream and file bodies: camelContext.getProperties().put(Exchange.LOG_DEBUG_BODY_STREAMS, true);

Regular logger sample

In the route below we log the incoming orders at DEBUG level before the order is processed:

from("activemq:orders").to("log:com.mycompany.order?level=DEBUG").to("bean:processOrder");

Or using Spring XML to define the route:

  <route>
    <from uri="activemq:orders"/>
    <to uri="log:com.mycompany.order?level=DEBUG"/>
    <to uri="bean:processOrder"/>
  </route> 

Regular logger with formatter sample

In the route below we log the incoming orders at INFO level before the order is processed.

from("activemq:orders").
    to("log:com.mycompany.order?showAll=true&multiline=true").to("bean:processOrder");

Throughput logger with groupSize sample

In the route below we log the throughput of the incoming orders at DEBUG level grouped by 10 messages.

from("activemq:orders").
    to("log:com.mycompany.order?level=DEBUG&groupSize=10").to("bean:processOrder");

Throughput logger with groupInterval sample

This route will result in message stats logged every 10s, with an initial 60s delay and stats should be displayed even if there isn't any message traffic.

from("activemq:orders").
to("log:com.mycompany.order?level=DEBUG&groupInterval=10000&groupDelay=60000&groupActiveOnly=false").to("bean:processOrder");

The following will be logged:

"Received: 1000 new messages, with total 2000 so far. Last group took: 10000 millis which is: 100 messages per second. average: 100"

Full customization of the logging output

Available as of Camel 2.11

With the options outlined in the Formatting section, you can control much of the output of the logger. However, log lines will always follow this structure:

Exchange[Id:ID-machine-local-50656-1234567901234-1-2, ExchangePattern:InOut, 
Properties:{CamelToEndpoint=log://org.apache.camel.component.log.TEST?showAll=true, 
CamelCreatedTimestamp=Thu Mar 28 00:00:00 WET 2013}, 
Headers:{breadcrumbId=ID-machine-local-50656-1234567901234-1-1}, BodyType:String, Body:Hello World, Out: null]

This format is unsuitable in some cases, perhaps because you need to...

• ... filter the headers and properties that are printed, to strike a balance between insight and verbosity.
• ... adjust the log message to whatever you deem most readable.
• ... tailor log messages for digestion by log mining systems, e.g. Splunk.
• ... print specific body types differently.
• ... etc.

Whenever you require absolute customization, you can create a class that implements the ExchangeFormatter interface. Within the format(Exchange) method you have access to the full Exchange, so you can select and extract the precise information you need, format it in a custom manner and return it. The return value will become the final log message.

You can have the Log component pick up your custom ExchangeFormatter in either of two ways:

Explicitly instantiating the LogComponent in your Registry:

<bean name="log" class="org.apache.camel.component.log.LogComponent">
   <property name="exchangeFormatter" ref="myCustomFormatter" />
</bean>

Convention over configuration:

Simply by registering a bean with the name logFormatter; the Log Component is intelligent enough to pick it up automatically.

<bean name="logFormatter" class="com.xyz.MyCustomExchangeFormatter" />

NOTE: the ExchangeFormatter gets applied to all Log endpoints within that Camel Context. If you need different ExchangeFormatters for different endpoints, just instantiate the LogComponent as many times as needed, and use the relevant bean name as the endpoint prefix.

See Also

• Configuring Camel
• Component
• Endpoint
• Getting Started

• Tracer
• How do I use log4j
• How do I use Java 1.4 logging
• LogEIP for using log directly in the DSL for human logs.