[logback-dev] [JIRA] Commented: (LBCLASSIC-185) Servlet filter which puts servlet-specific data into MDC

[Ralph Goers (JIRA)]

    [ http://jira.qos.ch/browse/LBCLASSIC-185?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=11513#action_11513 ] 

Ralph Goers commented on LBCLASSIC-185:
---------------------------------------

I don't have a problem with adding this to logback-examples but it isn't appropriate to add to logback-classic as there is no "correct" way to do this. For example,http://www.slf4j.org/extensions.html#event_logger shows code that works differently. In a lot of my implementations we have a hook into log in that captures most of the information in a Map that is stored in the session. Then the servlet filter just copies everything in the Map into the MDC and then adds a couple of request specific values. 

Furthermore, while it is a good goal to standardize some of these names in the MDC, doing that in a ServletFilter is horrible. We have implemented a class named RequestContext just for that purpose. It has all the key name constants and provides static methods such as 

public static String getRequestId() { 
  return MDC.get(REQUEST_ID); 
} 

That class becomes the glue to bind things together, not the ServletFilter.

> Servlet filter which puts servlet-specific data into MDC
> --------------------------------------------------------
>
>                 Key: LBCLASSIC-185
>                 URL: http://jira.qos.ch/browse/LBCLASSIC-185
>             Project: logback-classic
>          Issue Type: New Feature
>          Components: Other
>    Affects Versions: 0.9.18
>            Reporter: Torsten Juergeleit
>            Assignee: Ceki Gulcu
>         Attachments: logback-test.xml, RequestLogFilter.java, RequestLogFilterTest.java
>
>
> Attached you can find a servlet filter which implements a strategy to put servlet-specific data into the SL4F MDC using the following keys: 
> * {{slf4j.servlet.requestId}} - Unique ID of the single HTTP request handled by this filter 
> * {{slf4j.servlet.sessionId}} - ID of the HTTP session this HTTP request is associated with or "" if no HTTP session was created yet 
> * {{slf4j.servlet.contextPath}} - Web apps context path 
> * {{slf4j.servlet.userName}} - Name of authenticated user or "" if no user is authenticated 
> This data is removed after the request is processed. 
> The following configuration parameters are supported by this filter: 
> * {{maxSessionIdLength}} - limiting the HTTP session id length to a certain value, e.g. for WebLogic this could be 52 (default: -1 [unlimited]) 
> To use this filter add the following lines to the {{web.xml file}}: 
> <code>
>   <filter>
>     <filter-name>RequestLogFilter</filter-name>
>     <filter-class>ch.qos.logback.classic.RequestLogFilter</filter-class>
>     <init-param>
>       <param-name>maxSessionIdLength</param-name>
>       <param-value>52</param-value>
>     </init-param>
>   </filter><br>
>       :
>   <filter-mapping>
>     <filter-name>RequestLogFilter</filter-name>
>     <url-pattern>/*</url-pattern>
>   </filter-mapping>
> <code>
> An SLF4 Logger named {{ch.qos.logback.classic.RequestLogFilter}} is used to log the start end end of calling the filter chain. This information should go into a separate log file.

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