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From "Mark Thomas (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (DBCP-309) First example for FSContext is invalid
Date Tue, 11 Feb 2014 21:06:22 GMT

    [ https://issues.apache.org/jira/browse/DBCP-309?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13898311#comment-13898311
] 

Mark Thomas commented on DBCP-309:
----------------------------------

Caveat: I am no JNDI expert. The little I do know is gleaned from reverse engineering Tomcat's
JNDI implementation.

I think the example is wrong because it binds a reference. A reference will always result
in a new object being created when it is looked up. If the example binds a BasicDataSource
instance, it appears to behave as desired/expected.

As most users expect multiple JNDI look ups using the same name to return the same object,
Tomcat deliberately breaks the rules. By default, when Tomcat finds a reference, Tomcat resolves
that reference to an object and then replaces the reference in JNDI with the object. In later
Tomcat versions, this is configurable with the singleton property.

It isn't clear to me how implementing Referenceable will help. If anything, that will make
it worse as it would then be impossible to bind an instance of a BasicDataSource to JNDI as
the Reference would be bound.

I intend to tweak the examples to bind instances rather than References. This appears to be
consistent with Ondrej Tisler's approach above.

> First example for FSContext is invalid
> --------------------------------------
>
>                 Key: DBCP-309
>                 URL: https://issues.apache.org/jira/browse/DBCP-309
>             Project: Commons Dbcp
>          Issue Type: Bug
>    Affects Versions: 1.2.2
>            Reporter: Ondrej Tisler
>            Priority: Trivial
>             Fix For: 1.3.1, 1.4.1
>
>
> First example on page http://commons.apache.org/dbcp/guide/jndi-howto.html is invalid,
with this code every call of  
>   InitialContext ic2 = new InitialContext();
>   DataSource ds = (DataSource) ic2.lookup("jdbc/basic");
>   Connection conn = ds.getConnection();
>   conn.close();
> ends with new datasource with unclosed connection in it becase new Reference("javax.sql.DataSource",
 "org.apache.commons.dbcp.BasicDataSourceFactory", null); reference creates new DataSource
instead using created one while calling  ic2.lookup("jdbc/basic").
> At the end it ends with many opened connections to DB until JVM is ended.
> Second example I didn't test, i use direct aproach with manualy creating SharedPoolDataSource
and registring it in FSContext JNDI itself.



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