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h2. Log Component

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

{include:Uses Commons Logging}

h3. URI format

{code}
log:loggingCategory[?options]
{code}

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:

{code}
log:org.apache.camel.example?level=DEBUG
{code}

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.

{tip:title=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].
{tip}

h3. Options
{div:class=confluenceTableSmall}
|| Option || Default || Type || Description ||
| {{level}} | {{INFO}} | {{String}} | Logging level to use. Possible values: {{FATAL}}, {{ERROR}}, {{WARN}}, {{INFO}}, {{DEBUG}}, {{TRACE}}, {{OFF}} |
| | | | Throughput logging options. By default regular logging is used. |
| {{groupSize}} | {{null}} | {{Integer}} | An integer that specifies a group size for throughput logging.|
| {{groupInterval}} | {{null}} | {{Integer}} | *Camel 2.6*: If specified will group message stats by this time interval (in millis) |
| {{groupDelay}} | {{0}} | {{Integer}} | *Camel 2.6*: Set the initial delay for stats (in millis) |
| {{groupActiveOnly}} | {{true}} | {{boolean}} | *Camel 2.6*: If true, will hide stats when no new messages have been received for a time interval, if false, show stats regardless of message traffic | 
{div}
*note*: groupDelay and groupActiveOnly are only applicable when using groupInterval



h3. 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:
{div:class=confluenceTableSmall}
|| Option || Default || Description ||
| {{showAll}} | {{false}} | Quick option for turning all options on. (multiline, maxChars has to be manually set if to be used) |
| {{showExchangeId}} | {{false}} | Show the unique exchange ID. |
| {{showExchangePattern}} | {{true}} | *Camel 2.3:* Shows the Message Exchange Pattern (or MEP for short). |
| {{showProperties}} | {{false}} | Show the exchange properties. |
| {{showHeaders}} | {{false}} | Show the In message headers. |
| {{showBodyType}} | {{true}} | Show the In body Java type. |
| {{showBody}} | {{true}} | Show the In body. |
| {{showOut}} | {{false}} | If the exchange has an Out message, show the Out message. |
| {{showException}} | {{false}} | *Camel 2.0:* If the exchange has an exception, show the exception message (no stack trace). |
| {{showCaughtException}} | {{false}} | *Camel 2.0:* If the exchange has a caught exception, show the exception message (no stack trace). A caught exception is stored as a property on the exchange (using the key {{Exchange.EXCEPTION_CAUGHT}}) and for instance a {{doCatch}} can catch exceptions. See [Try Catch Finally]. |
| {{showStackTrace}} | {{false}} | *Camel 2.0:* Show the stack trace, if an exchange has an exception. Only effective if one of {{showAll}}, {{showException}} or {{showCaughtException}} are enabled. | 
| {{showFiles}} | {{false}} | *Camel 2.9:* Whether Camel should show file bodies or not (eg such as java.io.File). | 
| {{showFuture}} | {{false}} | *Camel 2.1:* Whether Camel should show {{java.util.concurrent.Future}} bodies or not. If enabled Camel could potentially wait until the {{Future}} task is done. Will by default not wait. |
| {{showStreams}} | {{false}} | *Camel 2.8:* Whether Camel should show stream bodies or not (eg such as java.io.InputStream). Beware if you enable this option then you may not be able later to access the message body as the stream have already been read by this logger. To remedy this you have to use [Stream Caching]. | 
| {{multiline}} | {{false}} | If {{true}}, each piece of information is logged on a new line. |
| {{maxChars}} | | *Camel 2.0:* Limits the number of characters logged per line. |
{div}

{tip:title=Logging stream bodies}
Camel will by default *not* log stream or files bodies. You can force Camel to log those by setting the property on the [CamelContext] properties
{code}
camelContext.getProperties().put(Exchange.LOG_DEBUG_BODY_STREAMS, true);
{code}
{tip}


h3. Regular logger sample
In the route below we log the incoming orders at {{DEBUG}} level before the order is processed:
{code:java}
from("activemq:orders").to("log:com.mycompany.order?level=DEBUG").to("bean:processOrder");
{code}

Or using Spring XML to define the route:
{code:xml}
  <route>
    <from uri="activemq:orders"/>
    <to uri="log:com.mycompany.order?level=DEBUG"/>
    <to uri="bean:processOrder"/>
  </route> 
{code}

h3. Regular logger with formatter sample
In the route below we log the incoming orders at {{INFO}} level before the order is processed.
{code:java}
from("activemq:orders").
    to("log:com.mycompany.order?showAll=true&multiline=true").to("bean:processOrder");
{code}

h3. Throughput logger with groupSize sample
In the route below we log the throughput of the incoming orders at {{DEBUG}} level grouped by 10 messages.
{code:java}
from("activemq:orders").
    to("log:com.mycompany.order?level=DEBUG?groupSize=10").to("bean:processOrder");
{code}

h3. 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.

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

The following will be logged:
{code}
"Received: 1000 new messages, with total 2000 so far. Last group took: 10000 millis which is: 100 messages per second. average: 100"
{code}


{include:Endpoint See Also}
* [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.