Full customization of the logging output - 6.3

Talend ESB Mediation Developer Guide

Talend Data Fabric
Talend Data Services Platform
Talend ESB
Talend MDM Platform
Talend Open Studio for ESB
Talend Real-Time Big Data Platform
Design and Development
Talend ESB

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,
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" />

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.

From Camel 2.11.2/2.12 onwards when using a custom log formatter, you can specify parameters in the log uri, which gets configured on the custom log formatter. Though when you do that you should define the "logFormatter" as prototype scoped so its not shared if you have different parameters, eg:

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

And then we can have Camel routes using the log uri with different options:

<to uri="log:foo?param1=foo&amp;param2=100"/>
<to uri="log:bar?param1=bar&amp;param2=200"/>

Using Log component in OSGi

Improvement as of Camel 2.12.4/2.13.1

When using Log component inside OSGi (e.g., in Karaf), the underlying logging mechanisms are provided by PAX logging. It searches for a bundle which invokes org.slf4j.LoggerFactory.getLogger() method and associates the bundle with the logger instance. Without specifying custom org.sfl4j.Logger instance, the logger created by Log component is associated with camel-core bundle.

In some scenarios it is required that the bundle associated with logger should be the bundle which contains route definition. To do this, either register single instance of org.slf4j.Logger in the Registry or reference it using logger URI parameter.