[logback-user] Context selectors useful?

[Ceki Gulcu]

Hello Lars,

You might want to check out logback 0.9.12-SNAPSHOT. It can be downloaded from

   http://logback.qos.ch/dist/logback-0.9.12-SNAPSHOT.tar.gz

I have tested logging separation in a Enterprise Application consisting of a 
stateless session and a web-app under JBoss 5.

In this version of logback, if you set up a env-entry for "logback/context-name" 
in JNDI, you no longer have to set an additional entry for the configuration 
file. For example, if "logback/context-name" is set to "MANGO", then the 
associated configuration file is named logback-MANGO.xml by convention. This 
makes things a bit easier, especially if you need to configure several EJBs or 
several web-apps.

The ejb-jar.xml file in my example reads

<?xml version="1.0"?>
<ejb-jar
  xmlns="http://java.sun.com/xml/ns/javaee"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://java.sun.com/xml/ns/javaee 
http://java.sun.com/xml/ns/javaee/ejb-jar_3_0.xsd"
  version="3.0">

   <enterprise-beans>
     <session>
       <ejb-name>Echo</ejb-name>
       <env-entry>
         <description>JNDI logging context for this app</description>
         <env-entry-name>logback/context-name</env-entry-name>
         <env-entry-type>java.lang.String</env-entry-type>
         <env-entry-value>vader</env-entry-value>
       </env-entry>
     </session>
   </enterprise-beans>
</ejb-jar>

and web.xml reads

<web-app id="kenobi" version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee"
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee 
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">

   <display-name>kenobi</display-name>

   <servlet>
     <servlet-name>KenobiServlet</servlet-name>
     <servlet-class>ch.qos.KenobiServlet</servlet-class>
   </servlet>

   <servlet-mapping>
     <servlet-name>KenobiServlet</servlet-name>
     <url-pattern>/kenobi/*</url-pattern>
   </servlet-mapping>

   <env-entry>
     <description>JNDI logging context for this app</description>
     <env-entry-name>logback/context-name</env-entry-name>
     <env-entry-type>java.lang.String</env-entry-type>
     <env-entry-value>star</env-entry-value>
   </env-entry>

   <!-- To refer local EJB's  -->
   <ejb-local-ref>
     <ejb-ref-name>ejb/Echo</ejb-ref-name>
     <ejb-ref-type>Session</ejb-ref-type>
     <local-home></local-home>
     <local>ch.qos.IEcho</local>
   </ejb-local-ref>

</web-app>

While it was easy to get jndi context selector to work in JBoss, I was not able 
to make it work under Geronimo. Ironically, because it uses SLF4J internally.

HTH,

Lars Ködderitzsch wrote:
> Hello Ceki,
> 
> thanks for the heads up on this issue on the mailing list.
> 
> Starting off I'd like to mention that for me the most wanted feature is
> separation of logging from different contexts (e.g. war's, ejb) of of an
> enterprise application (ear), without needing to resort to classloader
> stunts, multiple repeated logging configurations etc.
> That means that the contexts of an enterprise app should be able to use
> the same logging implementation (that is placed in the ear classloader)
> and the same logging configuration, but ultimately the log into
> different log files.
> This way it can be truely sorted out, which context logged which message.
> 
> To my knowledge such a thing is supported in neither logging
> implementations.
> Currently I am running this as a hack on log4j, based on a specialized
> appender which switches the underlying log file based on some thread
> local, which in turn is set by a special servlet filter in each web context.
> 
> At the time trying logback I thought that context selectors could
> achieve that in a better, more standardized and less hacky way.
> Ultimately I failed at the time and haven't looked back yet at logback.
> 
> So back to the question, yes, I would be very much interested in such a
> feature - be it contexts selectors or something else.
> 
> If your're interested I can elaborate more on the problem, so you can
> get a better understanding what would actually be needed.
> 
> Best regards,
> Lars
> 
> 
> Ceki Gulcu schrieb:
>> Hello all,
>>
>> I am in the process of fixing bugs related to context selectors in logback. 
>> However, while sometime ago I thought that context selectors were the wave of 
>> the future, I am increasingly skeptical about their usefulness (of context 
>> selectors).
>>
>> If you are using context selectors, could you please explain why?
>>

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