[slf4j-dev] [GIT] SLF4J: Simple Logging Facade for Java branch, master, updated. v1.5.9.RC1-25-g59753aa
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- Log -----------------------------------------------------------------
http://git.qos.ch/gitweb/?p=slf4j.git;a=commit;h=59753aaec81369c7f2b59818587cbedaf005a0c1
http://github.com/ceki/slf4j/commit/59753aaec81369c7f2b59818587cbedaf005a0c1
commit 59753aaec81369c7f2b59818587cbedaf005a0c1
Author: Ceki Gulcu <ceki at qos.ch>
Date: Sat Feb 27 15:24:54 2010 +0100
added a FAQ entry about wrapping SLF4J
diff --git a/slf4j-site/src/site/pages/faq.html b/slf4j-site/src/site/pages/faq.html
index 7da0d9d..eb9661c 100644
--- a/slf4j-site/src/site/pages/faq.html
+++ b/slf4j-site/src/site/pages/faq.html
@@ -71,6 +71,13 @@
</li>
<li>
+ <a href="#optional_dependency">In order to reduce the number of
+ dependencies of our software we would like to make SLF4J an
+ optional dependency. Is that a good idea?
+ </a>
+ </li>
+
+ <li>
<a href="#maven2">What about Maven 2 transitive
dependencies?
</a>
@@ -485,19 +492,87 @@ org.slf4j.impl.StaticLoggerBinder.SINGLETON from class org.slf4j.LoggerFactory
</dt>
<dd>
- <p>Embedded components such as libraries do not need and
- should not configure the underlying logging system. They
- invoke SLF4J to log but should let the end-user configure the
- logging environment. When embedded components try to configure
- logging on their own, they often override the end-user's
- wishes. At the end of the day, it is the end-user who has to
- read the logs and process them. She should be the person to
- decide how she wants her logging configured.
+ <p><b>Embedded components such as libraries not only do not need
+ to configure the underlying logging framework, they really
+ should not do so</b>. They should invoke SLF4J to log but should
+ let the end-user configure the logging environment. When
+ embedded components try to configure logging on their own, they
+ often override the end-user's wishes. At the end of the day, it
+ is the end-user who has to read the logs and process them. She
+ should be the person to decide how she wants her logging
+ configured.
</p>
<hr/>
</dd>
+ <!-- ======================================================= -->
+
+ <dt>
+ <a name="optional_dependency" href="#optional_dependency">In
+ order to reduce the number of dependencies of our software we
+ would like to make SLF4J an optional dependency. Is that a good
+ idea?
+ </a>
+ </dt>
+
+ <dd>
+ <p><a
+ href="http://stackoverflow.com/questions/978670/is-it-worth-wrapping-a-logging-framework-in-an-additional-layer">This
+ question pops up</a> whenever a software project reaches a point
+ where it needs to devise a logging strategy.
+ </p>
+
+ <p>Let Wombat be a software library with very few
+ dependencies. If SLF4J is chosen as Wombat's logging API, then a
+ new dependency on <em>slf4j-api.jar</em> will be added to
+ Wombat's list of dependencies. Given that writing a logging
+ wrapper does not seem that hard, some developers will be tempted
+ to wrap SLF4J and link with it only if it is already present on
+ the classpath, making SLF4J an optional dependency of Wombat. In
+ addition to solving the dependency problem, the wrapper will
+ isolate Wombat from SLF4J;s API ensuring that logging in Wombat
+ is future-proof.
+ </p>
+
+ <p>On the other hand, any SLF4J-wrapper by definition depends on
+ SLF4J. It is bound to have the same general API. If in the
+ future a new and significantly different logging API comes
+ along, code that uses the wrapper will be equally difficult to
+ migrate to the new API as code that used SLF4J directly. Thus,
+ the wrapper is not likely to future-proof your code, but to make
+ it heavier by adding an additional indirection on top SLF4J
+ which is an indirection in itself.
+ </p>
+
+ <p>While one can come up with a seemingly working SLF4J-wrapper
+ within hours, many small technical issues will emerge over time
+ which Wombat developers will have to deal with. Note that SLF4J
+ has evolved over several years and has 170 bug reports filed
+ against it.</p>
+
+ <p>It is reasonable to assume that in most projects Wombat will
+ be one dependency among many. If each library had its own
+ logging wrapper, then each wrapper would presumably need to be
+ configured separately. Thus, instead of having to deal with one
+ logging framework, namely SLF4J, the user of Wombat would have
+ to detail with Wombat's logging wrapper as well. The problem
+ will be compounded by each framework that comes up with its own
+ wrapper in order to make SLF4J optional. (Configuring 5
+ different logging wrappers is not exactly exciting nor
+ endearing.)
+ </p>
+
+ <p>For this reason, developers of frameworks should resist the
+ temptation to write their own logging wrapper. Not only is it a
+ waste of time of the developer, it will actually make life more
+ difficult for the users of said frameworks.
+ </p>
+ </dd>
+
+
+ <!-- ======================================================= -->
+
<dt><a name="maven2" href="#maven2">What about Maven2
transitive dependencies? </a>
</dt>
@@ -531,7 +606,7 @@ org.slf4j.impl.StaticLoggerBinder.SINGLETON from class org.slf4j.LoggerFactory
<p>Thus, as far as your users are concerned you are exporting
slf4j-api as a transitive dependency of your library, but not
- any SLF4J-binding or an underlying logging system.
+ any SLF4J-binding or any underlying logging system.
</p>
<hr/>
-----------------------------------------------------------------------
Summary of changes:
slf4j-site/src/site/pages/faq.html | 93 ++++++++++++++++++++++++++++++++----
1 files changed, 84 insertions(+), 9 deletions(-)
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