5 Network Data Model Overview

This chapter explains the concepts and operations related to the network data model for representing capabilities or objects that are modeled as nodes and links (vertices and edges) in a graph.

This model is called the Oracle Spatial Network Data Model feature, or simply Network Data Model. This chapter assumes that you are familiar with the main Oracle Spatial concepts, data types, and operations, as documented in Oracle Spatial Developer's Guide.

Although this chapter discusses some network-related terms as they relate to Oracle Spatial, it assumes that you are familiar with basic network data modeling concepts.

• Introduction to Network Modeling
  In many applications, capabilities or objects are modeled as nodes and links in a network. The network model contains logical information such as connectivity relationships among nodes and links, directions of links, and costs of nodes and links.
• Main Steps in Using the Network Data Model
  This topic summarizes the main steps for working with the Network Data Model feature in Oracle Spatial. It refers to important concepts, structures, and operations that are described in detail in other topics.
• Network Data Model Concepts
  A network is a type of mathematical graph that captures relationships between objects using connectivity.
• Network Applications
  Networks are used in applications to find how different objects are connected to each other.
• Network Hierarchy
  Some network applications require representations at different levels of abstraction. For example, two major processes might be represented as nodes with a link between them at the highest level of abstraction, and each major process might have several subordinate processes that are represented as nodes and links at the next level down.
• Network User Data
  For user data defined through the xxx_SDO_NETWORK_USER_DATA views, the default user data I/O implementation (LODUserDataIOSDO) is used to access the user data during network analysis. However, some user data is not included in the node or link table, and thus cannot be registered through xxx_SDO_NETWORK_USER_DATA views.
• Feature Modeling
  You can model objects of interest on the network as features.
• Feature Modeling Using Network Feature Editing (NFE)
  Network feature editing (NFE) lets you create and manage an NFE model. An NFE model extends the feature modeling capabilities by enabling you to visualize and manipulate features using Java Swing components and a PL/SQL API.
• Network Constraints
  Network constraints are restrictions defined on network analysis computations.
• Network Buffers
  Network Data Model (NDM) introduces the network buffer representation that captures the coverage and cost information on top of the network representation. In contrast to the spatial buffer approach, the cost information of network buffers is accurate and efficient.
• Network Analysis Using Load on Demand
  Load on demand means that during network analysis, a network partition is not loaded into memory until the analysis has reached this partition while exploring the network.
• Network Management and Analysis Using Contraction Hierarchies
  Contraction hierarchies can be used to find the shortest path in a graph, potentially providing better performance than traditional shortest path algorithms like Dijkstra or A*.
• Network Data Model Tables
  The connectivity information for a spatial network is stored in two tables: a node table and a link table. In addition, path information can be stored in a path table and a path-link table.
• Network Data Model and Network Feature Editing (NFE) Model Metadata Views
  Two sets of network metadata views can be created for each schema (user): xxx_SDO_NETWORK_xxxxxx and xxx_SDO_NFE_MODEL_xxxxxx, where the initial xxx can be USER or ALL. These views are created, as needed, by Spatial.
• Network Data Model Application Programming Interface
  The Oracle Spatial Network Data Model feature includes two client application programming interfaces (APIs): a PL/SQL interface provided by the SDO_NET package and a Java interface.
• Cross-Schema Network Access
  If database users other than the network owner need to read a network into memory, you need to do one of the following options.
• Network Examples
  This topic presents several Network Data Model examples.
• Network Data Model Tutorial and Other Resources
  Network Data Model learning resources are available.
• README File for Spatial and Related Features
  A README.txt file supplements the information in the following manuals: