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Re: [OpenSAML] Signature Validation Logging

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  • From: Brent Putman <>
  • To:
  • Subject: Re: [OpenSAML] Signature Validation Logging
  • Date: Thu, 26 May 2011 16:36:09 -0400

Oh, yeah, absolutely remove the nop one. That is a no-op impl of the
API that silently discards all logging. You only want 1 binding jar on
the classpath. Since you are using logback, that's your binding jar.
So you want to not include any of the other binding jars that come with
slf4j itself. Those are for example listed about halfway down the page

You just want the slf4j-api jar and any bridge jars for other logging
frameworks that are used by components in your environment (e.g. the

On 5/26/11 4:21 PM, Swapna Gupta wrote:
> Thanks. I am continuing to research. When I do the following in my code,
> what I find is that the Log contains a Logger which is an instance of
> org.slf4j.helpers.NOPLogger.
> org.apache.commons.logging.Log log =
> LogFactory.getLog(;
> And there is an slfj-nop jar in the classpath.
> Could this be the reason nothing is getting logged?
> -----Original Message-----
> From:
> [mailto:]
> On Behalf Of Brent Putman
> Sent: Thursday, May 26, 2011 3:09 PM
> To:
> Subject: Re: [OpenSAML] Signature Validation Logging
> No, not really. In fact, before, you should have at least been seeing
> things on the console from OpenSAML itself logging to logback. If you
> aren't, you'd have to ask the logback people or search around their
> support stuff.
> Also, to be clear, in this context of logback's internal default config,
> "console" means stdout. So if you have stdout redirected somewhere,
> that's where it would be going.
> On 5/26/11 3:58 PM, Swapna Gupta wrote:
>> Thanks. So I added jcl-over-slf4j.jar to the classpath, still no messages.
>> Do I need to do anything more?
>> Thanks.
>> -----Original Message-----
>> From:
>> [mailto:]
>> On Behalf Of Brent Putman
>> Sent: Thursday, May 26, 2011 12:50 PM
>> To:
>> Subject: Re: [OpenSAML] Signature Validation Logging
>> Actually
>> On 5/26/11 12:50 PM, Swapna Gupta wrote:
>>> Thanks! I have added logback-core and logback-classic jars to the
>>> classpath. What else should I do to get the Debug messages from
>>> DigesterOuputStream? Reading the Logback documentation, it appears it is
>>> by default set to log at debug level to the console. But I don't see any
>>> messages on the console.
>> Ah, sorry, I spoke a little too quickly. To get logging from our
>> OpenSAML classes themselves, you do need to install an slf4j binding,
>> such as Logback.
>> To get logging from other libraries which don't use slf4j natively, you
>> need to address that logging framework's requirements. That
>> DigesterOutputStream is from Apache XML Security (Santuario) and uses
>> Apache Jakarta Commons Logging (JCL). So you need to get the actual log
>> output from JCL.
>> If you still want to use an SLF4J-based library like Logback as the
>> actual logging impl in your OpenSAML-based application (which is fine,
>> it's pretty good), then you need to install the SLF4J JCL to SLF4J
>> bridge jar. See:
>> It's the one listed there as jcl-over-slf4j.
>> Logback does log to the console by default. If you want it to go to a
>> file, etc. you just need a logback config file. The easiest is to just
>> put in your classpath. See the logback user manual for details.

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