Bhargav Ram

Look @windows bea svc if servers are on windws

It depends on directory structure. Is your websvc application look @WEB-INF/classes for the required classes ? I think 'NO'
May be, you have to jar the required classses websvc requires and keep the jar in APP-INF/lib.

Please try that and let me know ...

How do you call authenticator ? Is it in the code ?

Please post the code how you are doing for the JNDI lookup. May be, modify the code to look for 'sampleDS'. Also cerate data source name as 'sampleDS'

You can change the connection pool to any database you want, with out changing the source code.
Your source code should just look for JNDI name for datasource.

Weblogic 7 to 10 is a big leap. (People normally do it in steps, from 7 to 8 and then to 9 )It depends on what type of project you have.
Do you have portals (weblogic portal) ?

Following is the link which you may follow to stat with.

http://download.oracle.com/docs/cd/E12840_01/wlw/docs103/guide/upgrading/conChangesDuringUpgrade.html

Do you really need nodeManager to start the 2nd managed server ? Why don't you start manually ?

I think userid/passwd you assign at the time of installation of weblogic package ...