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From Gerrit Binnenmars <>
Subject Re: [jira] [Created] (CELIX-87) Log writer to syslog
Date Wed, 02 Oct 2013 19:50:51 GMT
Hello Alexander,

See my comments below.
> Hi Gerrit,
> While I like the idea of logging to the system log, I think there are
> several points which I'd like to mention.
> First one is logging in the framework itself. Currently there is some
> output to standard out, but probably also some missing parts. To be able to
> do something with these entries the framework needs to be updated to use
> the LogService (if present). This is a bug/improvement of the Celix could
> and should be done (imo).
> Second one: The LogService is based on the Compendium spec, and already
> supports the Log Writer construction. More specifically, it is possible to
> register a LogListener to the LogReaderService. See chapter 101 of the
> compendium spec, and the LogWriter of Celix.
> So making a component which takes log entries and adds them to the system
> log can already be written.
Thanks, this was the information I was looking for.
> Third one: you ask for easy filtering between Celix and Application
> logging. The OSGi API for the log service does not have any explicit
> support for this, eg there is no log category or similar which can be used.
> However, log entries can have a reference to the bundle that made the log.
> But maybe it is easier to handle such filtering in your own specific syslog
> output component..
> Regarding the properties:
> The log service itself doesn't have any properties defined in the spec. But
> looking at Felix it probably makes sense to have some to specify the
> maximum number of messages to keep in memory and to specify wether debug
> messages should be stored.
> These properties only influence the storage of entries, and has nothing to
> do with subscribed listeners, so even if debug messages are not stored they
> are still send to the listeners.
> All other properties can be handled in the specific listener
> implementation. In other words, the LogService is only meant for creating
> log entries. With the ReaderService and Listeners it is possible to process
> those logs in a specific way best suited for the actual user.
So, the LogWriter needs a log_level property to do some filtering.
> So while I do think it is interesting for Celix to have a syslog writer, I
> am not sure if the specific request for filtering will fit in a generic
> solution. It might be better to implement this writer for your specific use
> case. A good example of a listener is the LogWriter bundle which writes to
> standard out.
Agree with you, we can work on the LogWriter as a new bundle. I think it 
is still useful to add this to Celix for other users.
> 2013/10/1 Gerrit Binnenmars (JIRA) <>
>> Gerrit Binnenmars created CELIX-87:
>> --------------------------------------
>>               Summary: Log writer to syslog
>>                   Key: CELIX-87
>>                   URL:
>>               Project: Celix
>>            Issue Type: New Feature
>>      Affects Versions: 0.0.2-incubating
>>           Environment: Linux system
>>              Reporter: Gerrit Binnenmars
>> We would like to have the internal Celix logging in the Linux syslog
>> output mechanism.
>> Also bundles need to be able to register their own logWriter (in the
>> syslog output it shall be easy to filter between Celix logging and
>> application logging)
>> Configurable shall be: output file name (default: /var/log/messages)
>> Level (to enable/disable logging at different levels)
>> Special text that can be used for filtering
>> --
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