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Logging the bundle name [message #644919]

Tue, 14 December 2010 18:18

Raman Gupta

Messages: 12
Registered: December 2010

Junior Member

Is there something I can add to the logback pattern layout to log the bundle name?

Background: I have a shared class that is instantiated as a bean within the Spring contexts of several bundles. When this bean logs an Exception it is unclear as to which bundle the exception occurred within. The ideal approach would be to have the logging system tell me this automatically rather than adding information to the log message manually.

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Re: Logging the bundle name [message #645023 is a reply to message #644919]

Wed, 15 December 2010 09:20

Glyn Normington

Messages: 1222
Registered: July 2009

Senior Member

I think it would be necessary to add the bundle identity (bundle symbolic name and version or possibly bundle id) to Logback's Mapped Diagnostic Context before it would be possible to refer to the bundle identity in an encoder pattern.

This could be done, but I'm not convinced that Virgo should incur that overhead on every logging call.

An alternative would be to build logic into the exception constructor to derive the bundle name and add it to the exception message. You could examine the stack and then use FrameworkUtil.getBundle(Class< ? >) to get the Bundle from the appropriate class in the stack.

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Re: Logging the bundle name [message #652177 is a reply to message #645023]

Wed, 02 February 2011 21:32

Raman Gupta

Messages: 12
Registered: December 2010

Junior Member

How about adding the bundle information to the MDC within the proxies generated for OSGi service calls?

i.e.

try {
  MDC.put("Bundle-SymbolicName", ...);
  MDC.put("Bundle-ID", ...);
  <service call here>
} finally {
  MDC.remove("Bundle-SymbolicName");
  MDC.remove("Bundle-ID");
}

Glyn - is this what you were thinking of when you said that it could be done but you were concerned about overhead?

Cheers,
Raman

[Updated on: Wed, 02 February 2011 21:32]

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Re: Logging the bundle name [message #652178 is a reply to message #652177]

Wed, 02 February 2011 21:37

Glyn Normington

Messages: 1222
Registered: July 2009

Senior Member

Not really: the overhead I had in mind was if Virgo was to add those items to a MDC for every logging call.

However, I think gathering the necessary information when the exception occurs is a better design. Would that work in your situation?

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Re: Logging the bundle name [message #652183 is a reply to message #652178]

Wed, 02 February 2011 22:11

Raman Gupta

Messages: 12
Registered: December 2010

Junior Member

It probably would but only for exceptions, and only those exceptions which I specifically instrumented. What would be better is a generic solution that would work for all logging messages.

What do you think about the approach I described? The only overhead would be the MDC put and release calls on each service call. Unfortunately, it won't cover every situation -- for example, code that runs outside the context of a service call, but it would help nonetheless.

Cheers,
Raman

[Updated on: Wed, 02 February 2011 22:29]

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Re: Logging the bundle name [message #652356 is a reply to message #652183]

Thu, 03 February 2011 16:28

Frieder Heugel

Messages: 61
Registered: October 2010
Location: Basel, CH

Member

Hi Raman,

maybe using AspectJ would be a solution for your problem. You could write an aspect that is intercepting every log call or catching any exception. Then you could add the needed information and continue with the regular program.

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Re: Logging the bundle name [message #652368 is a reply to message #652356]

Thu, 03 February 2011 17:00

Glyn Normington

Messages: 1222
Registered: July 2009

Senior Member

Hi Raman

Your approach seems reasonable.

I would personally choose AspectJ, like Frieder suggested, and use compile-time weaving for simplicity of interaction with OSGi.

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Re: Logging the bundle name [message #652405 is a reply to message #652368]

Thu, 03 February 2011 18:45

Raman Gupta

Messages: 12
Registered: December 2010

Junior Member

Using Aspects sounds like a reasonable interim approach.

I guess in the long run though this sort of thing will need to be part of the toolset. Not being able to determine out of the box which bundle logged a message is a big information deficit, and I'm surprised this isn't a common request.

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Re: Logging the bundle name [message #652441 is a reply to message #652405]

Thu, 03 February 2011 22:43

Glyn Normington

Messages: 1222
Registered: July 2009

Senior Member

I think the usual approach is to observe the class name in a log entry and infer the bundle from it.

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Re: Logging the bundle name [message #652450 is a reply to message #652441]

Thu, 03 February 2011 23:55

Raman Gupta

Messages: 12
Registered: December 2010

Junior Member

Fair enough -- this situation has come up for me in cases where multiple service bundles access shared utility bundles, and the log statements in the shared utility bundles need to list the important contextual information, which is the service bundle.

But in that case, a baked in solution wouldn't know which bundle to log anyway, so we are back to the explicit aspect/MDC solution. Makes sense.

Thanks.

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