Every utility network has a network topology. The job of a network topology is to manage information about features and maintain the connectivity between features. Information regarding both processes is stored inside of a network topology. For features to connect they must abide by the feature restrictions of a utility network and applicable network rules must exist.
Information inside of a network topology is stored in a graph persisted as binary pages. This allows tracing and diagram functions to read and process information about the network in an efficient manner (as opposed to retrieving information directly from features in a network). Each time a portion of the graph is accessed, that portion is cached and given a time stamp to record the last moment of access. This allows client applications to access the same portion of the graph, avoiding the need to go to the database directly, which can further improve processing time.
States of a network topology
A network topology has two states: enabled or disabled. Only the owner of the utility network can manage these states. To learn how to manage the network topology state see the Tools and commands section below.
The Enable Network Topology tool can be used to generate errors against current network features or to fully enable the network topology for network functionality such as tracing and generating diagrams. Network topology errors can be generated after a utility network has been configured to discover error features in your utility network before the data is registered as branch versioned. This uses the Only generate errors advanced option and is useful for doing preliminary QA of your data before the utility network is consumed. After the initial QA of your network data is complete, the utility network feature dataset is registered as branch versioned and the network topology can be enabled to allow tracing and network diagram tasks. After the network topology is enabled, dirty areas are created to track certain edits made against the network feature classes.
There are different requirements for using the Enable network topology tool. To understand the different workflows and requirements for enabling a network topology, see Enable a network topology.
A network topology is disabled to perform management tasks such as adding rules or assigning association roles to assets. When the network topology is disabled, a single dirty area covers the extent of the utility network service territory and edits are not tracked by dirty areas. Disabling a network topology is recommended when loading large amounts of data, as it helps to reduce processing time. When a topology is enabled again, the network topology is reconstructed for all utility network features.
The network properties for a utility network includes network topology metadata in the Network Topology section. Information such as the current enabled state, dirty area count, time stamps, and duration for different network topology actions. The network properties can also be used to view the count for error features.
There are some network configuration tasks that can only be performed before the network topology is enabled for the first time. To learn more, see Network topology actions.
Dirty areas and error features
Areas of a network topology can become out of date or invalid. Two utility network mechanisms are used as markers or flags to indicate where these areas are.
Dirty areas mark modified features on a map that are out of date in a network topology. Dirty areas are created to flag areas where edits have been made against features, associations, and network attributes so that the network topology index is updated by validation. A network topology is validated to remove dirty areas.
While tracing through a dirty area is allowed, it may yield unexpected results and therefore should not be relied on. Validating the topology for the area that will be traced will remove dirty areas and help ensure trace results reflect what is on the map. To learn more, read about the Validate Consistency option within the Trace tool configuration.
Error features are generated by the system when a feature in the utility network is in violation of established rules and restrictions. Descriptions associated with error features help you understand what violation is occurring. Error features can be inspected and fixed and then be removed the next time the network topology is validated or enabled.
Validate a network topology
When a network topology is enabled, portions of the network that have been edited or modified become out of date in the topology. The content you see on a map may not be what is stored in the network topology. As discussed, dirty areas are used to mark information that is new to the network and has not been reflected in the network topology. The network topology must be validated to include these changes in tracing and diagram operations. Analytics (tracing and diagrams) reading the network topology may be reading outdated information and could therefore return inaccurate results. The network topology for a given area of the network is only as current as the last time it was enabled or validated (whichever occurred last).
For optimal performance when validating a network topology, it is important to keep the spatial index up to date for network feature classes. After creating a utility network and appending new features, the spatial indexes should be rebuilt using the Rebuild Indexes tool.
Validation of the network topology is not an automatic operation that is performed after every edit. The validation process can be initiated by using the Validate command on the Utility Network tab, or via the Validate Network Topology tool. The Validate Network Topology geoprocessing tool takes advantage of asynchronous processing and is recommended for longer-running validation operations that use the full extent or include a large number of edits.
See Validate a network topology for more information.
Two geographical extent options are offered for validating a network topology: full geographical extent or current map extent.
- The current extent option is more common and recommended when edits have been performed in a localized area or work zone. This provides flexibility for editors to couple edit events together and run a single validation event (reduces the overall time it takes to perform edits and update a network topology).
- Validating the entire extent involves a potentially heavy operation depending on the size, complexity, and number of dirty areas in your network. This operation is recommended when there are many edits scattered geographically throughout the network that need to be validated. After validating a topology, dirty areas may still be present if the current extent was validated and it did not encompass all of the dirty areas in the network.
During a network topology validation event, various network properties, restrictions, and consistencies are evaluated. Among those on the list are rules and edge connectivity policies. Items causing inconsistent or ambiguous situations are tracked via error features. For the list of error situations, see Error feature management.
If an edit operation modified features that are part of one or more subnetwork (added, modified, or removed features), the following will result from validating a network topology:
- Subnetworks are marked as dirty for subnetworks that intersect with dirty areas. This is reflected for the Is dirty attribute in the Subnetworks table and SubnetLine feature class.
- Network diagrams are marked as inconsistent for non-system network diagrams that include features intersecting the dirty areas, and subnetwork system diagrams are marked as inconsistent.
The Update Subnetwork tool is used to update a dirty subnetwork and switch subnetwork system diagrams back to a consistent state. Non-system network diagrams can be made consistent with network features by using the Update Diagram tool. To learn more about the process for updating dirty subnetworks, see Update a subnetwork.
Tools and commands
There are several tools and commands used to manage the state of the network topology for a utility network. Some topology management tasks can be performed client/server using data accessed directly from a geodatabase or via services using a feature layer. Regardless of the datasource, all of the utility network configuration tools require an active portal connection using the portal utility network owner.
A Validate command exists on the Utility Network Data tab set. This command, along with the Validate Network Topology tool, allows you to validate a network topology for the current extent or the entire geographic extent of a utility network. A validation event (tool or command) can take place in the Default version or a child version by any user that has permissions to edit the version. See Validate a network topology to review both workflows.
The Disable Network Topology tool can be executed on the Default version or a user version. It is necessary to disable a network topology when performing configuration tasks for a utility network or performing a large data load.
Tip:If the topology is disabled in a user version, the reconcile process can be used to inherit the topology state from the default branch version.
Through the application of branch versioning, a utility network supports archiving and editor tracking capabilities. This allows edits to the network features and the network topology to be temporally aware. Analytic operations to be performed at the current moment or at a specified moment in the past. The topology must be enabled at these moments for a trace or diagram operation to be performed.