title: Oracle: Connection intermittent issue using JDBC url
body: <p>SQL developer provides multiple methods to connect to a database instance.</p>
  
  <p>If I choose the <code>Basic</code> method, which provides <code>hostname</code>, <code>port</code> and <code>SID</code> into input box separately, database connection runs without any issue.</p>
  
  <p>However, if I choose <code>Advanced</code> method, which provides the following JDBC url in a whole：</p>
  
  <pre><code>jdbc:oracle:thin:@hostname:port:SID
  </code></pre>
  
  <p>and hit <code>Test</code> button, sometimes the status shows <code>Success</code>, but sometimes it pop up an error message like this:</p>
  
  <pre><code>Status : Failure -Test failed: Listener refused the connection with the following error:
  ORA-12519, TNS:no appropriate service handler found
  </code></pre>
  
  <p>So why and how there is such a difference with both methods? Is it a bug from SQL developer?</p>
  
  <h2>UPDATE 1</h2>
  
  <p>I found the issue happens exactly when I run a Java EE application with JNDI connection to the same database instance, so database instance listener cannot tolerate more than one access if one of them is JNDI? I think I just make that up...</p>