Re: Logging Domains committed to sandbox (dodgy cvs spam email address though)

[Ceki Gülcü <ce...@qos.ch>]

At 08:01 AM 4/1/2007, Paul Smith wrote:
[snip]

>Now, back to the discussion:
>
>Markers appear to allow one to decorate a single Logging event in a
>point in code with a specific marker, and I'm assuming here that one
>could come up with some sort of Composite Marker that would allow a
>single event to belong to several dimensions (i'll use 'dimensions'
>here simply to disambiguate Markers with my 'Domain'
>implementation).  This is where I think Markers are more fined
>grained, because I can see a place in code looking like this (in
>purely psuedo-code because I haven't played with Markers yet):
>
>logger.debug( {"timing", "search", "documents"}, "Document search
>took " + timing + "ms to execute");

Markers are already composite. They can be nested 
multiple times. So instead of the above, you could write:

Marker myMarker = MarkerFactory.getMarker("MY_MARKER);
Marker timing= MarkerFactory.getMarker("TIMING);
Marker search= MarkerFactory.getMarker("SEARCH);
Marker documents = MarkerFactory.getMarker("DOCUMENTS);

myMarker.addChild(timing);
myMarker.addChild(search);
myMarker.addChild(documents );


logger.debug(myMarker, "Document search  took " + timing + "ms to execute");

or better yet,

logger.debug(myMarker, "Document search  took {} ms to execute", timing);


>Imagine the above logging statement belonged to a Class called
>com.mycompany.documents.DocSearch.  It has a Logger as part of it's
>package name hierarchy, plus that single logging statement declares
>that the logging event belongs to some other dimensions related to
>timings, an imaginary overall Search architecture, and specifically
>some documents module within an application.
>
>The Annotation-based method can't handle this finer-grained nature of
>timing.  With Annotations on the class, you can only describe where
>the entire classes' Logging Statements fit in, so in the above
>example I can probably annotate DocSearch with "search" and with
>"documents", but I can't imply that every logging statement in this
>class belongs to Timing because that wouldn't be accurate.  However I
>can add some dimension to all Logger statements with one annotation
>rather than need to specify it with every logging statement.

Yep, that's the gist of it. Markers are more 
accurate while annotated loggers are wholesale (thus maybe more convenient).

>>The way you have implemented domains to be compatible with
>>Log4j-1.2.xx is certainly compelling.  However, the future seems to
>>be markers.  I wonder if it would be more helpful to simply call
>>this an implementation of markers where the usage is more
>>prescribed and makes it unnecessary to pass markers via the Logger
>>API.  In future versions of Log4j, which might support markers (as,
>>maybe, a result of supporting the SLF4J API), additional markers
>>may be supplied via the Logger API in addition to those defined as
>>annotations?
>
>I wonder whether Markers and Annotations could work together.
>Imagine something like this:
>
>@LoggingDomains( domains="search", "documents")
>public class DocSearch {
>         private static final Logger LOG = Logger.getLogger(DocSearch.class);
>...
>
>public void search(){
>...
>         LOG.info( {"timing"}, "The Doc Search took " + time + "ms");
>
>If at the point of Logger declaration the Logger class could inspect
>the class for the annotation and pre-register a set of Markers used
>for every logging statement, and at the point of logging, add any
>additionally supplied Markers.
>
>Markers are starting to sound like they have a relationship with
>event Properties.

Yah, you could consider a marker as an event 
property whereas domain is a logger property.

In principle, nothing prevents a marker to be applied on a logger.

For example, one could write:


@Marker( contains={"search", "documents"})
public class DocSearch {
         private static final Logger LOG = Logger.getLogger(DocSearch.class);
        Marker TIMING = MarkerFactory.getMarker("TIMING")l
...

public void search(){
...
         LOG.info( TIMING, "The Doc Search took " + time + "ms");


[snip]

>If my code does nothing more than stimulate some discussion and is
>thrown out in favour of other ideas, then it has accomplished one of
>my goals.  :)

Your code was quite thought provoking. In a way, 
it allows one to decorate a class with a marker 
which could be pretty useful indeed.

>cheers,
>
>Paul Smith

-- 
Ceki Gülcü
Logback: The reliable, generic, fast and flexible logging framework for Java.
http://logback.qos.ch


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