As Avi said, the createDescriptor() method requires that your connection be an 'OracleConnection'. Internally, the createDescriptor() method *casts* your connection object to 'OracleConnection'. We faced the same problem in Weblogic 5.1. Due to time & other constraints we had no other option but to use a *direct* connection, using thin driver, instead of a Connection Pool. Try using the direct connection until you find a permanent solution.
oracle.sql.ARRAY a = new oracle.sql.ARRAY(descrip, connection, s);
cs.setArray(1,a);
I guess this is not the correct way of passing arrays. You may have to use the cs.setARRAY(1,a) method. This method is part of the OracleCallableStatement class. So you have to cast your CallableStatement to OracleCallableStatement like this
Pls let us know your progress in this.
Arvind