Describe relationship between Oracle Net, client PCs, and database system.
Oracle Net communication with ClientPcs
Oracle Net is a complicated beast, and there are many ways to configure it. Let us assume,
for the moment, that you have a database server and several client PCs all running on a network, and all configured to use TCP/IP.
The following diagram shows a legacy diagram from Oracle Net8, which has been replaced with Oracle Network Topology and Cloud Computing.
Oracle Net Key Components
The above diagram represents the most common configuration of Oracle Net, and it's the one we are going to use for this course.
Oracle Net Listener
A key component of Oracle Net is the Oracle Net Listener. This is a process (or service on NT) that runs on the database server,
and that monitors the network for incoming database connection requests. In order to access a database instance, such as the COIN instance, from a remote system, you must first tell the listener that the instance exists.
This is done by editing a file named listener.ora that sits on the database server.
Oracle Net Client
Oracle Net also runs on client PCs that need to access an Oracle database. Just as you need to tell the Oracle Net Listener on the server about the databases on that server,
you need to tell the Oracle Net client software on a PC about the databases to which you want to connect.
In order to access COIN from a client computer, you need to tell the client that a COIN database exists,
and you also need to point the client to the server where the listener for the COIN database resides.
This is done by editing a file named tnsnames.ora that sits on the client PC.