Re: [JBoss-user] Opening multiple databases in on session bean

[David J. <dav...@di...>]

I don't know why it would be more than 2x slower.

If you access 2 or more resource managers (databases) within one
transaction, you need 2pc or xa in order to assure that you actually have
ACID tx properties.  If you are using the LocalTx wrapper and/or non-xa
databases, you don't have 2pc or xa, so if something goes wrong, you may
end up with inconsitent data.  The warning is pointing this out.

david jencks

On 2002.06.07 09:20:25 -0400 Greg Noorman wrote:
> I have started working with Jboss and was trying to access 2 different
> mysql
> databases on the same server.  When I do this the server comes up with
> the
> following warning:
> 
> 13:44:38,984 WARN  [LocalTxConnectionManager$LocalConnectionEventListener]
> prepare called on a local tx. You are not getting the semantics you
> expect!
> 13:44:38,985 WARN  [LocalTxConnectionManager$LocalConnectionEventListener]
> prepare called on a local tx. You are not getting the semantics you
> expect!
> 
> If only access one of the databases (either one), no warnings and
> response
> is quick.  If I hit both I get the warning and much slower response. I
> suppose because it has to process the Event.  In all cases, it does
> retrieve
> the correct information from the databases.
> Any ideas about this warning???
> 
> We are running jboss-3.0.0_tomcat-4.0.3 on a Solaris system using jdk
> 1.3.
> 
> Here is the code:
> 
> package cae.mysql;
> 
> import java.util.*;
> import javax.ejb.SessionBean;
> import javax.naming.*;
> import javax.rmi.PortableRemoteObject;
> import java.sql.*;
> 
> public class MySQLBean implements SessionBean {
>     public void ejbCreate() {}
>     public void ejbPostCreate() {}
>     public String getTL (String tlname) throws java.rmi.RemoteException {
>         return getchk();
>     }
>     public String getchk() {
>         PreparedStatement pstmt = null;
>         Connection conn = null;
>         try {
>             conn = getConnectionchk();
>             pstmt = conn.prepareStatement("Select fval from checkit where
> find = 1");
>             ResultSet rs = pstmt.executeQuery();
>             if (rs.next()) {
>                 return rs.getString("fval");
>             }
>         } catch (Exception e) {
>             e.printStackTrace();
>         } finally {
>             try { if (pstmt != null) pstmt.close(); }
>             catch (Exception e) {}
>             try { if (conn != null) conn.close(); }
>             catch (Exception e) {}
>         }
>         return "Shucks";
>     }
>     public String getTL() {
>         PreparedStatement pstmt = null;
>         Connection conn = null;
>         try {
>             conn = getConnectionTL();
>             pstmt = conn.prepareStatement("Select des_num from contains
> where draw_num = 174183");
>             ResultSet rs = pstmt.executeQuery();
>             if (rs.next()) {
>                 return rs.getString("des_num");
>             }
>         } catch (Exception e) {
>             e.printStackTrace();
>         } finally {
>             try { if (pstmt != null) pstmt.close(); }
>             catch (Exception e) {}
>             try { if (conn != null) conn.close(); }
>             catch (Exception e) {}
>         }
>         return "Dang, Missed again<br>\n";
>     }
>     public Connection getConnectionchk() throws Exception {
>         try {
>             Context ctx = new InitialContext();
>             javax.sql.DataSource ds =
> (javax.sql.DataSource)ctx.lookup("java:comp/env/jdbc/chkDS");
>             return ds.getConnection();
>         } catch (Exception e) {
>             System.err.println("Couldn't get datasource!");
>             e.printStackTrace();
>             throw e;
>         }
>     }
>     public Connection getConnectionTL() throws Exception {
>         try {
>             Context ctx = new InitialContext();
>             javax.sql.DataSource ds =
> (javax.sql.DataSource)ctx.lookup("java:comp/env/jdbc/TravLogDS");
>             return ds.getConnection();
>         } catch (Exception e) {
>             System.err.println("Couldn't get datasource!");
>             e.printStackTrace();
>             throw e;
>         }
>     }
>     public void ejbActivate() {}
>     public void ejbPassivate() {}
>     public void ejbRemove() {}
>     public void setSessionContext(javax.ejb.SessionContext ec) {}
> }
> 
> 
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