Diky za odkaz. Radu veci jsem pochopil, ale problem stale trva.

Tomcat mi stale vraci:

javax.servlet.ServletException: Unable to get connection, DataSource invalid: "java.sql.SQLException: No suitable driver"

Na strance 
http://tomcat.apache.org/tomcat-5.5-doc/jndi-datasource-examples-howto.html#Database%20Connection%20Pool%20(DBCP)%20Configurations
jsem si precetl:


Configure the JNDI DataSource in Tomcat by adding a declaration for your resource to |$CATALINA_HOME/conf/server.xml|.

Add this in between the |</Context>| tag of the examples context and the |</Host>| tag closing the localhost definition.

Provozuju NetBeans na WinXP, a Tomcat mi vratil:
Using CATALINA_HOME: C:\Program Files\netbeans-5.0\enterprise2\jakarta-tomcat-5.5.9

Podle toho se tedy pokousim upravit soubor server.xml. Bohuzel nevim, jestli spravne. Tag <context> v souboru server.xml vubec neni a tak jsem to pridal az na jeho konec:

    <Context path="/DB2" docBase="DB2"
             debug="5" reloadable="true" crossContext="true">
      <Resource name            = "jdbc/cegelec"
                auth            = "Container"
                type            = "javax.sql.DataSource"
                username        = "sa"
                password        = "test"
                driverClassName = "net.sourceforge.jtds.jdbc.Driver"
url = "jdbc:jtds:sqlserver://delphi/cegelec_ostra"
                maxActive       = "8"
                maxIdle         = "4"/>
     </Context>
     </Host>
   </Engine>
 </Service>
</Server>


V jine casti dokumentace se zminuji, ze se musi editovat soubor meta-inf/context.xml. To jsem taky zkousel.

Odpovedet emailem