Lesson 1

Oracle's Connection Manager, or CMAN, is a application that is available with Oracle Enterprise Edition.
CMAN is very similar to the Oracle Network Services, and provides support for connection concentration, network access control, and multi-protocol support. One of the shortcomings of the Net8 listener was that it would accept connections from any Oracle client that knows the required information (port number of the listener, host address, and database name). With CMAN you can specify which remote databases are allowed to make listener connections.

Below is a comprehensive explanation of the purpose and function of the cman.ora file in Oracle Network Services:
Purpose:

• Configures the Oracle Connection Manager (CMAN), a middle-tier component that manages and controls client-to-database connections within Oracle Network Services.
• It's essential for CMAN to function correctly.

Function:

• Stores configuration parameters: It holds various settings that control CMAN's behavior, including:
  1. Listening addresses for CMAN processes
  2. Access control rules for managing connections
  3. Performance tuning parameters
  4. Logging options
  5. Security settings like SSL/TLS configuration

Key Components:

1. Listening Endpoints:
   1. Specifies the protocol addresses (TCP/IP, IPC) and ports on which CMAN will listen for incoming connections.
   2. Example:

      `ADDRESS = (PROTOCOL=TCP)(HOST=192.168.1.100)(PORT=1630)`
      

2. Access Control Rule List:
   1. Defines rules to determine which connections are accepted, rejected, or dropped based on client IP addresses, service names, or other criteria.
   2. Enables fine-grained access control to CMAN services.
3. Parameter List:
   • Sets various attributes for CMAN operation, such as:
     1. Connection pooling
     2. Logging levels
     3. Tracing
     4. Resource limits
     5. Security settings

Location:

• By default, found in the `$ORACLE_HOME/network/admin` directory on UNIX-like systems and `%ORACLE_HOME%\network\admin` on Windows.
• Can also be located in these alternative directories:
  1. Directory specified by the `TNS_ADMIN` environment variable
  2. Node's global configuration directory (e.g., `/var/opt/oracle` on Solaris)

Importance:

• CMAN relies on the cman.ora file for its configuration.
• CMAN won't start if the cman.ora file is absent or invalid.

Additional Notes:

• CMAN is typically used in large-scale or high-security environments to:
  1. Centralize connection management
  2. Improve performance and scalability
  3. Enhance security
  4. Simplify network configuration
• It's not a mandatory component for all Oracle database deployments.

Oracle Enterprise Manager 10g Agent (10g Agent) is the replacement for Oracle Intelligent Agent (OIA) starting with Oracle Database 10g. OIA was used in previous versions of Oracle Database to monitor and manage the database, while the 10g Agent provides enhanced functionality and improved performance. The 10g Agent uses the same management framework as Oracle Enterprise Manager 10g, which is the main tool used to manage and monitor the entire Oracle environment, including databases, middleware, and applications. So it's safe to say that Oracle Enterprise Manager 10g Agent has replaced Oracle Intelligent Agent.
Oracle Intelligent Agent existed for Oracle versions 8.1.5, 8i, 9i.
For Oracle 10g the Intelligent Agent does not exist and instead a different agent is used, known as the Enterprise Manager 10g agent.

After completing this module, you will be able to:

1. Describe the features of the Connection Manager
2. Configure the Connection Manager
3. Start and stop the Connection Manager
4. Use SQL*Net with connections to multiple protocols

Oracle Connection Manager is a software component that resides on its own computer, separate from a client or an Oracle Database server. It proxies and screens requests for the database server. In addition, it multiplexes database sessions. In its session multiplexing role, Oracle Connection Manager funnels multiple sessions through a single transport protocol connection to a particular destination. In this way, Oracle Connection Manager reduces the demand on resources needed to maintain multiple sessions between two processes by enabling the Oracle Database server to use fewer connection end points for incoming requests. As an access control filter, Oracle Connection Manager controls access to Oracle databases.

The "Oracle Names Control Utility" is desupported and has not been available starting with Oracle Database 10g. This includes all the related control utility commands. Oracle Database clients cannot use a Names Server to resolve connect strings. Migrate your applications to Oracle Internet Directory with LDAP directory naming
Connection Concentration only existed for Net8 and Oracle 8i. After Oracle 8i you will not find any documentation on "Connection Concentration".
In the next lesson, you will examine the function of CMAN's three server programs.