Why do you need / need to exclude JDBC for this? This is why JDBC exists and why Oracle provides JDBC drivers for its databases. Even if there is some kind of low-level protocol documentation for what you are trying to do, you will not be guaranteed that it will be portable between Oracle releases, etc.
I am going to make the assumption that you want to eliminate the installation of the Oracle client. If so, make sure you are using the JDBC type 4 driver or the Oracle thin driver - available at http://www.oracle.com/technetwork/database/enterprise-edition/jdbc-112010-090769.html . This does exactly what you are probably trying to do - connect to the Oracle database through pure Java without requiring any other installed software - although it will technically still be JDBC.
If you still insist on continuing without any Oracle client components (even including only the JDBC driver for Oracle type 4), here are some additional links that might be of interest:
Where can I get the Oracles Explorer Level Protocol specification?
Oracle Outside of Oracle, these are just a few wire-level driver providers. Similarly, unlike driver providers, Oracle is the only one with permission to distribute it. And before asking, I never saw the specification myself. All my knowledge of the protocol is based on years of research and significant trial and error.
This project is available (available) http://sourceforge.net/projects/sibylnet/ , but has not seen any updates since 2008-10-07, and it doesn’t have any files or source code.