ASF_20_SRC_AUTO/src/documentation/xdocs/faq/faq-databases.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE faqs PUBLIC "-//APACHE//DTD FAQ V1.0//EN" "../dtd/faq-v10.dtd">

<faqs title="Database FAQs">
<faq>
  <question>
    When I try to use the Connection pooling code, I get the following exception:
    "Could not get the datasource java.sql.SQLException: You cannot
    get a Poolable before the pool is initialized".  What's going on?
  </question>
  <answer>
    <p>
      The most common reason for this exception is that the driver was not loaded.
      Cocoon uses an initial parameter in the "web.xml" file to automatically load
      classes on startup.  This way, the class is loaded only once and the server's
      time is spent doing more productive things.  Make sure the following entry
      is in your "web.xml" file.
    </p>

    <source><![CDATA[
<init-param>
 <param-name>load-class</param-name>
 <param-value>
   <!-- comma or whitespace separated list of fully
     qualified class names to load on startup.
   -->
   oracle.jdbc.driver.OracleDriver
 </param-value>
</init-param>
]]></source>

    <p>
      If the class is loaded correctly, and you are still getting this error, then there
      is probably an error in your connection information.  The SQLException
      above is thrown when there are no open connections to the database.
    </p>
  </answer>
</faq>

<faq>
 <question>
   The sql samples don't run.
 </question>
 <answer>
   <p>
     The sql samples are working when deploing the war file using the build
     system:</p>
       <source>
./build.sh \
   -Dinstall.war=path/to/tomcat/webapps install
</source>

   <p>
     This command will take care of the path inside the configuration file to the database resources.
   </p>
 </answer>
</faq>

<faq>
 <question>
   I've been able to run the database samples, but they don't run anymore.
 </question>
 <answer>
   <p>
    This happens when the servlet engine has been stopped abruptly (e.g. with ctrl-C).
   </p>
   <p>
    Hsqldb - the database used by C2 samples - is a single-process engine that
    locks the database by setting the "modified" entry in
    "WEB-INF/db/cocoondb.properties" to the value "yes" while some JDBC
    connections exist. 
   </p>
   <p>
    With connection pooling, there's always some connections opened, and they're
    not closed properly when you stop abruptly the servlet engine, so the database
    stays in locked state and connections are refused at the next server startup.
   </p>
   <p>
    To unlock the database, change manually "modified" to "no" in the "cocoondb.properties"
    before restarting the server.
   </p>
 </answer>
</faq>

<faq>
 <question>
   I get an AbstractMethodError when Cocoon tries to query my database.
 </question>
 <answer>
   <p>
    In this case Cocoon returns a "500 internal error" result, and the 
    AbstractMethodError is visible in the tomcat logs after a call to
    Connection.prepareStatement(...).
   </p>
   <p>
    This happens when the JDBC driver being used does not implement the
    JDBC 1.2 interfaces: using its default configuration, the SQLTransformer 
    calls a version of the JDBC Connection.prepareStatement(...) method that is not
    available in pre-1.2 drivers.
   </p>
   <p>
    To avoid this problem, configure the SQLTransformer with "old-driver=true" in the
    sitemap, as shown in this example:
   </p>
    
        <source><![CDATA[
        <map:transformer 
          logger="sitemap.transformer.sql" 
          name="sql" 
          src="org.apache.cocoon.transformation.SQLTransformer"
        >
          <old-driver>true</old-driver>
        </map:transformer> 
        ]]></source>
 </answer>
</faq>

<faq>
 <question>
   Where can I find more information about connecting to databases using Cocoon?
 </question>
 <answer>
  <p>
Learn more about connecting to databases by downloading the free chapter, <link href="http://www.newriders.com/books/product.asp?product_id={C3C05052-BE3B-4E06-A60A-13FB40AF58F6}" >A User's Look at the Cocoon architecture,</link> from Langham and Ziegeler's <em>Cocoon: Building XML Applications</em> available at the New Riders web site.
  </p>
</answer>
</faq>

</faqs>