Referencing External Resources

The deployer should not change web.xml, so init parameters cannot be used for him.
Instead, use the Java Networking and Directory Interface (JNDI API) to access external resources

Use environment entries like

<env-entry> <!-->
  <description>Send pincode by mail</description>
  <!--used as part of the JNDI lookup-->
  <env-entry-name>mainPincode</env-entry-name>
  <!--default value-->
  <env-entry-value>false</env-entry-value>
  <!--the FQDN of the entry-->
  <env-entry-type>java.lang.Boolean</env-entry-type>
</env-entry>

If the object you are reference is an EJB component then use

<ejb-ref>
  <description>Cruise ship cabin</description>
  <ejb-ref-name>ejb/CabinHome</ejb-ref-name>
  <!--Entity or Session: type of EJB component-->
  <ejb-ref-type>Entity</ejb-ref-type>
  <home>com.titan.cabin.CabinHome</home>
  <remote>com.titan.cabin.Cabin</remote>
</ejb-ref>

then the servlet can get a reference to it with:

InitialContext initCtx = new InitialContext();
Object ref = initCtx.lookup("java:comp/env/ejb/CabinHome");
CabinHome home = (CabinHome) PortableRemoteOject
   .narrow(ref, CabinHome.class);