text: Q:
  
  Configuring Grails to use own DataSource implementation or to proxy the standard DataSource
  
  In an application I want to use my own implementation of javax.sql.DataSource that extends the standard org.apache.commons.dbcp.BasicDataSource used by Grails and adds the functionality to set the client identifier based on the currently logged in user at the Grails application.
  What is the best way to change the underlying javax.sql.DataSource implementation in a Grails application?
  At the moment I see two possibilities: 
  
  change the implementation of the DataSource that is used by Grails
  proxy the DataSource that is used by Grails and add the functionality with AOP
  
  Any hints on how to deal with this requirement?
  
  A:
  
  here is my resources.groovy
  import org.codehaus.groovy.grails.commons.ConfigurationHolder as CH
  
  // Place your Spring DSL code here
  beans = {
  
      /**
       * c3P0 pooled data source that forces renewal of DB connections of certain age 
       * to prevent stale/closed DB connections and evicts excess idle connections
       * Still using the JDBC configuration settings from DataSource.groovy
       * to have easy environment specific setup available
       */
      dataSource(com.mchange.v2.c3p0.ComboPooledDataSource) { bean ->
          bean.destroyMethod = 'close'
          //use grails' datasource configuration for connection user, password, driver and JDBC url
          user = CH.config.dataSource.username 
          password = CH.config.dataSource.password
          driverClass = CH.config.dataSource.driverClassName
          jdbcUrl = CH.config.dataSource.url
          //force connections to renew after 2 hours
          maxConnectionAge = 2 * 60 * 60
          //get rid too many of idle connections after 30 minutes 
          maxIdleTimeExcessConnections = 30 * 60
      }
  
  }
  
  i'm using c3p0 ComboPooledDataSource
  
  A:
  
  did you try configuring your own datasource in resources.groovy?  Here is a blog post (not mine) that goes over the process
  http://burtbeckwith.com/blog/?p=312
  the stuff you need is at the end.
  
  