[logback-user] Configuring properties via XML

[ceki]

Regarding race conditions, note that the MDC manages contextual 
information on a per thread basis [1].

[1] http://logback.qos.ch/manual/mdc.html

On 09.11.2012 01:42, Adam Gordon wrote:
> I was able to get this working using the SiftingAppender.  Thanks!  My
> request filter pulls the child app name from the URI and sets the MDC
> variable which yields the appropriate behavior of Spring logging to the
> correct log files.
>
> One final question:  is this going to be subject to race conditions?  If
> user A is using child app A at the same time as user B is using child
> app B, they're going to go through the same request filter so it's
> feasible that A's value gets set and that thread goes to do some
> intensive business logic (which let's say has a bunch of logging), B's
> thread comes in and changes the value, will A's thread suddenly switch
> log files?
>
> I guess the real question is when does the SiftingAppender query MDC for
> the value and when does it update it for the nested <appender>?
>
> --adam
>
> http://gordonizer.com
>
>
>
> On Thu, Nov 8, 2012 at 2:27 PM, ceki <ceki at qos.ch <mailto:ceki at qos.ch>>
> wrote:
>
>
>     Have you looked at SiftingAppender [1]? If you can set an MDC
>     variable at the beginning of a request served by each child app, the
>     results should be rather close to what you are aiming. Give it a try.
>
>     [1] http://logback.qos.ch/manual/__appenders.html#SiftingAppender
>     <http://logback.qos.ch/manual/appenders.html#SiftingAppender>
>
>
>     On 08.11.2012 19:54, Adam Gordon wrote:
>
>         Ok, I really should have thought about what I really needed
>         before posting.
>
>         We have a "parent" GWT web application and we have children
>         applications
>         that are plugged into it.  The children can run as standalone web
>         applications but this is really only for development.  Since
>         each child
>         can run independently, each has its own logback.xml file.
>
>         Unfortunately, when the parent is built, the children are just
>         JAR file
>         dependencies and the parent also has it's own logback.xml file.
>
>         Using only the parent's logback.xml file, we can configure different
>         appenders (and thus different log files) for each of the
>         children, but
>         this only works because of the child namespacing (the Java package
>         name).  The parent's logback.xml defines the root logger to use the
>         parent's appender.  What this means is that if the children are
>         using a
>         common framework, say Spring, all the Spring logging doesn't go
>         into the
>         correct child's logfile, but rather the parent's.
>
>         What we need is a way to either allow each child it's own,
>         completely
>         separate logging configuration or we need to "tag" the logging
>         statement
>         in the parent's log file with some name that indicates which
>         child the
>         message came from.
>
>         I was looking at the concept of a context selector, but it
>         wasn't clear
>         how I'd be able to configure this to return the correct
>         LoggingContext
>         depending on which child issued the logging statement.
>
>         Alternatively, I suppose I could add a filter which "sets" the
>         current
>         logging context based on the request URI - the children's
>         request URIs
>         are also namespaced so that each child's request URI always
>         starts with
>         /child_name/...
>
>         Was this clear?  Do anyone have any thoughts on how best to approach
>         this problem?
>
>         Thanks,
>
>         --adam
>
>         http://gordonizer.com
>
>
>
>         On Thu, Nov 8, 2012 at 11:01 AM, ceki <ceki at qos.ch
>         <mailto:ceki at qos.ch> <mailto:ceki at qos.ch <mailto:ceki at qos.ch>>>
>
>         wrote:
>
>
>              Please see [1] in the docs. For your use case, you need to
>         define
>              the property in the context scope [2].
>
>              [1]
>         http://logback.qos.ch/manual/____configuration.html#____variableSubstitution
>         <http://logback.qos.ch/manual/__configuration.html#__variableSubstitution>
>
>         <http://logback.qos.ch/manual/__configuration.html#__variableSubstitution
>         <http://logback.qos.ch/manual/configuration.html#variableSubstitution>>
>              [2]
>         http://logback.qos.ch/manual/____configuration.html#scopes
>         <http://logback.qos.ch/manual/__configuration.html#scopes>
>
>              <http://logback.qos.ch/manual/__configuration.html#scopes
>         <http://logback.qos.ch/manual/configuration.html#scopes>>
>
>
>              On 08.11.2012 18:54, Adam Gordon wrote:
>
>                  The Layout chapter indicates it supports property value
>                  retrieval via
>                  %property{key} and states that the logging context is
>         where one
>                  might
>                  put a property (along w/ System properties).  I believe
>         log4j
>                  did this
>                  w/ the <param name="key_name" value="some_value">
>         element in the
>                  <appender> and referenced it via %properties{key_name}.
>
>                  I'm not seeing how to do this in Logback in XML. Would
>         it go in the
>                  <logger> element?  What's the syntax?  Could someone please
>                  point me to
>                  the relevant section in the appropriate chapter of the
>         manual?
>
>                  Thanks,
>
>                  --adam
>
>
>
>     --
>     Ceki
>     65% of statistics are made up on the spot



-- 
Ceki
65% of statistics are made up on the spot