two_task和TTC

lovegigi1999

"TWO_TASK"
==========

"TWO_TASK" is a Unix environment variable that can be set to a default TNS
connect string.  For example, you issue the following command at a Unix prompt:

    % setenv TWO_TASK test_db.world

When you invoke a tool such as SQL*Plus, you would only need to type:

    % sqlplus scott/tiger

in order to be connected to the TNS address of "test_db.world".  Some users
prefer this to typing:

    % sqlplus scott/tiger@test_db.world

Two-Task Common
===============
Two-Task Common provides character set and data type conversion between
different character sets or formats on the client and server.  
This layer is
optimized to perform conversion only when required on a per connection basis.
At the time of initial connection, Two Task Common is responsible for
evaluating differences in internal data and character set representations and
determining whether conversions are required for the two computers to
communicate.