Evolution of Network Protocols

Topology is a term used to describe the overall configuration of the Oracle Net Services distributed databases, including all clients and Oracle servers. In large topologies it is not uncommon to find different communications protocols ^[1] as the network may span different operating environments, such as DEC, mainframes, and Novell. In theory, any of the following protocols can run under any topology. Due to the overwhelming use of the UNIX operating system, the most popular protocol has become TCP/IP, but Oracle supports some of the more obscure protocols as well.

1. DNA (DecNet): DEC's Distributed Networking Architect: Introduced in 1975 by DEC for use in the VMS operating system.
2. TCP/IP: Transmission Control Protocol / Internet Protocol: TCP is a standard protocol that enables a process on one machine to send a stream of data to another machine. IP is protocol that provides a packet delivery service across a network.
3. SNA: IBM's System Network Architecture: Introduced in 1974, SNA is a standard protocol and the one most commonly used today.
4. X.25: Developed by Bell Canada, X.25 is the basis for ISDN and the OSI model for open systems.

Again, while Oracle Net Services has the ability to support cross-protocol communications, the vast majority of Oracle Net Services implementations utilize TCP/IP.

The topology data model of Oracle Spatial lets you work with data about

1. nodes,
2. edges, and
3. faces

in a topology.
For example, United States Census geographic data is provided in terms of nodes, chains, and polygons, and this data can be represented using the Spatial topology data model. You can store information about topological elements and geometry layers in Oracle Spatial tables and metadata views. You can then perform certain Spatial operations referencing the topological elements, for example, finding which chains (such as streets) have any spatial interaction with a specific polygon entity (such as a park). The Spatial data structures and data types support the topology data model which are required to populate and manipulate the structures. You can use this information to write a program to convert your topological data into formats usable with Spatial.

The evolution of network protocols within the context of Oracle Spatial Topology has been closely tied to the development and enhancement of Oracle's database technologies, particularly in how they manage and communicate spatial data across distributed systems. Here's an overview of this evolution:

• Early Implementations: Oracle 7: Inter-database communication, including for spatial data, started with Oracle 7 in 1992. This version introduced SQLNet, which was pivotal for enabling databases to interact over various network topologies. Although not specifically tailored for spatial data, SQLNet provided the foundational network communication protocol that would later support spatial data distribution.
• Development in Network Protocols: Transparent Network Substrate (TNS): Oracle's proprietary protocol, TNS, evolved to provide a consistent communication framework across different network topologies, operating systems, and hardware. In the context of spatial topology, TNS allows for seamless interaction between Oracle clients and databases with spatial data, abstracting the underlying network protocol details. This abstraction is crucial for handling complex spatial queries and operations across a network where topology data might be distributed.
• Specific to Spatial Topology: Oracle Spatial Topology Data Model: Introduced with Oracle Spatial, the topology data model allows for the representation of spatial data in terms of nodes, edges, and faces. This model supports various network topologies like bus, star, ring, and mesh, by providing structures like the SDO_TOPO_GEOMETRY data type for managing topological elements. The evolution here includes better integration with network protocols for efficient data exchange, such as using TCP/IP for point-to-point or more complex network configurations.
• Advancements in Network Data Model: Network Data Model: Oracle's Spatial and Graph features evolved to include more sophisticated network modeling capabilities, where nodes and links could represent not just geographical features but also logical connections in networks. This model supports logical networks (purely connectivity information) and spatial networks (both connectivity and geometry). Protocols like TCP/IP are used to manage network communication, allowing for operations like path analysis or network analysis across different network topologies.
• Modern Enhancements: Oracle 12c and Beyond: With Oracle 12c, there was a significant leap in inter-database communication, introducing features like pluggable databases, which improved data management across networks. This version and subsequent ones like Oracle 19c have enhanced the capability to handle spatial data over networks with increased performance, security, and scalability. Protocols have evolved to support these features, ensuring that spatial topology can be effectively managed in distributed environments.
• Network Topology and Protocols: The evolution in Oracle has paralleled the broader shift from simpler network topologies like bus or ring to more complex ones like star or mesh, supported by protocols that can handle diverse network environments. Oracle's network protocols have adapted to support these topologies, ensuring that spatial data integrity and performance are maintained regardless of the underlying network structure.

In summary, the evolution of network protocols within Oracle's spatial topology framework has focused on providing robust, scalable, and efficient means to handle and communicate spatial data across distributed systems, adapting to various network topologies and ensuring data consistency and performance. This evolution of network protocols within Oracle has always been influenced by broader networking trends and technologies. One fundamental shift in network communication that laid the groundwork for much of what Oracle's network protocols leverage today is the concept of packet-switching networks.

Packet-switching revolutionized data transmission by breaking messages into smaller, manageable packets that can travel independently across different network paths before being reassembled at their destination. This method not only optimizes network resource utilization but also enhances reliability and speed, which are crucial for database systems like Oracle Spatial Topology:

• Efficiency: Packet-switching allows for dynamic routing, which can be particularly beneficial when dealing with spatial data that might require real-time or near-real-time updates across geographically dispersed systems.
• Scalability: As Oracle databases grew in complexity and size, packet-switching provided the necessary scalability to handle increased data volumes and user loads without significant degradation in performance.
• Reliability: If one path fails, packets can be rerouted, ensuring that spatial data continues to flow even with network disruptions, a feature critical for maintaining data integrity in applications like GIS.
• Support for Advanced Features: Techniques like load balancing, which are essential in modern database environments, rely on the principles of packet-switching to distribute data efficiently across network nodes.

Thus, the development and optimization of network protocols in Oracle Spatial Topology have been intrinsically linked to the capabilities and innovations provided by packet-switching networks. This foundation has allowed Oracle to build sophisticated data models and communication strategies that are both robust and adaptable to various network conditions. This transition naturally leads from the specific application of protocols in Oracle to the broader technological shift to packet-switching, illustrating how this networking paradigm has directly impacted and enhanced database operations and spatial data management.
In the next lesson, the evolution of databases from centralized to distributed will be discussed.

[1] protocol: In Oracle Net Services, a protocol is a set of rules and standards that govern how data is exchanged between a client application and an Oracle database server over a network. These protocols, such as TCP/IP, enable communication and ensure reliable transmission of data between the two entities.