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Lesson 15How to manage distributed database connectivity?
ObjectiveExplain how Oracle Network Services Manage Database Connections.

Managing Database Connections for Distributed Databases using Oracle Net Services

Oracle Net Services plays a crucial role in implementing and managing distributed databases by providing a comprehensive suite of tools and services that facilitate communication between clients and Oracle databases across a network. This article will discuss how Oracle Net Services manages database connections to implement distributed databases effectively.
  1. Connection Establishment: Oracle Net Services establishes connections between clients and databases by leveraging a set of components, including Oracle Net Listener, Oracle Net, and Oracle Connection Manager. The Oracle Net Listener listens for incoming client connection requests and routes them to the appropriate database instance. Oracle Net, which serves as the primary network protocol for communication between clients and databases, ensures seamless and reliable data exchange. Oracle Connection Manager, an optional component, enables advanced connection management capabilities, such as connection pooling and multiplexing.
  2. Service Naming and Resolution: Oracle Net Services uses service names to identify and connect to database services, abstracting the physical location and connection details of the database. This approach simplifies the process of managing and configuring client connections, particularly in large-scale distributed environments. Clients can use various naming methods to resolve service names, including Local Naming (TNSNAMES.ORA), Directory Naming (LDAP), and Easy Connect Naming.
  3. Connection Load Balancing: Oracle Net Services provides connection load balancing, which distributes incoming client connection requests across multiple instances of an Oracle database service. The Oracle Net Listener takes into account the current workload and performance metrics of each instance when routing client connections, ensuring that clients connect to the most suitable instance. This feature optimizes resource utilization and improves the overall performance of the distributed database system.
  4. Connection Pooling and Multiplexing: Oracle Net Services supports connection pooling and multiplexing to manage database connections more efficiently in distributed environments. Connection pooling allows clients to share a pool of pre-established connections to the database, reducing the overhead of connection establishment and improving resource usage. Connection multiplexing enables multiple client connections to share a single network connection between the client and the server, reducing the number of network connections required and conserving network resources.
  5. Failover and High Availability:Oracle Net Services provides built-in support for failover and high availability to ensure uninterrupted access to distributed databases. Transparent Application Failover (TAF) allows clients to automatically reconnect to a different instance of an Oracle database service in the event of a failure, while Fast Connection Failover (FCF) enables the rapid detection and failover of client connections to an available instance. These features help maintain the availability and reliability of distributed databases in the face of failures or network issues.
  6. Network Security: Oracle Net Services offers robust network security features to protect data and communications in distributed database environments. These include support for industry-standard security protocols such as SSL/TLS, data encryption and integrity algorithms, and various authentication methods. Oracle Advanced Security, an optional component, provides additional security capabilities, such as data encryption at rest, data redaction, and fine-grained access control.

In conclusion, Oracle Net Services manages database connections for distributed databases by providing a comprehensive set of tools and services that enable seamless communication, efficient connection management, high availability, and robust security. These features ensure reliable, performant, and secure access to distributed databases, making Oracle Net Services a vital component in implementing distributed database systems.
This module has presented a large amount of technical information, and you may be feeling a bit overwhelmed by now. The second course in this series examines in greater detail each of the components discussed here. Let us take a close look now at how Oracle manages incoming connections. When the Oracle listener detects an incoming request, it spawns, or creates, a process on the server.
This process, in turn, connects to the Oracle database. In this fashion, the Oracle listener bequeaths connections and then returns to its duty of listening for incoming database requests.

  1. A request is made in the SQL with a databse link name
  2. The Oracle listener intercepts the incoming request and creates an Oracle session.
  3. This in turn creates a UNIX process to manage the remote connection

Overview of Distributed Architectures

  1. Organization and economic factors in distributed databases
  2. The factors that create distributed database
  3. Specialized databases
  4. Rightsizing
  5. Corporate acquisitions
  6. Essentials of distributed databases
  7. Data integrity management
  8. Transparency features
  9. Location transparency
  10. Domains and location transparency
  11. Performance and tuning methods
  12. Interoperability features
  13. Replication and reliability
  14. Master-slave replication
  15. Operating system copy replication
  16. Replication advantages
  17. Types of distributed databases
  18. Architectural distribution
  19. Geographical distribution
  20. The myth of open systems
  21. Solutions to distributed database communication
  22. The impact of client-server on distributed systems
  23. Distributed database analysis and design

Once the server process is established, it makes a direct connection to the Oracle database using the USER ID and password that were provided in the database link. Again, do not be concerned if this is not yet completely clear. We will return to this topic in greater detail later in the course. The next lesson concludes this module.