I should be able to achieve this within given technology stack: OSB and DB adatpers only.Well, if all READ, CREATE and UPDATE are DB operations in a same DB or in multiple local DB's which can have DBLinks between each other then why don't you wrap these operations in a stored procedure or in a DB function and invoke that SP/Function through DB adapter? By this way, you may utilize the better control of PL/SQL and at the same time, no need to worry about concurrency at OSB as well.
Could you please explain more detail how we can achieve this with SP PL/SQL.Nothing special. Just implement your select, update, insert logic in a SP and call that SP from SOA using DB adapter. Use "SELECT FOR UPDATE" locking feature of Oracle DB in your SELECT statement to lock the row(s).
If we make it SP, we'll have to make some changes in already implemented DB calls, right?Yes, instead of having three DML calls to DB, you will end up having only one call and that too to Stored Procedure.
Just try to get help with someone who knows PL/SQL in your org or go through some tutorials over internet.Thanks for your suggestion. I can manage to understand the basic level of SQL and PL/SQL