Working with the Connect and Disconnect commands when editing a Geometric Network
The following post was contributed by Craig Gillgrass a product engineer on the geodatabase team who spends the lion’s share of his time working with geometric networks.
The topic of when to use the Connect and Disconnect commands when editing geometric network features came up a couple times during our Geometric Network session. Based on those discussions and other questions from users I’ve re-written the help topic on these commands. What follows is a variation of the new help topic which should be available online soon.
As covered in the topic About editing geometric network features; the geometric network automatically maintains connectivity between network features based on geometric coincidence. For example, when using the ArcMap snapping environment, if a junction is added along an edge, or one edge is added along another edge, they will automatically become connected to one another. The ArcMap snapping functionality will guarantee geometric coincidence when adding new network features amongst existing network features and ensure the proper connectivity is established. Therefore, it is generally not necessary to use the Connect and Disconnect commands with most network editing workflows, but there are some exceptions.
Connect:
The Connect command creates topological relationships between the selected feature and the features to which it is geometrically coincident; if features are not geometrically coincident with the selected feature, connectivity will not be established. Connect will also honor the subsumption rules of the geometric network; orphan junctions will be subsumed by user defined junctions when connectivity is established.
The following diagram demonstrates how Connect works in certain situations; the dashed arrow indicates on which feature Connect is being used. The legend can be used for both diagrams:
Disconnect:
The Disconnect command removes the topological associations a feature has to other features in the network. Disconnect does not delete the selected feature from the database or geometric network. It also does not remove the logical network information for the feature.
Disconnecting a connected junction will leave an orphan junction in its place. Disconnecting an edge honors the geometric network rule that an edge must always have junctions at its end points. Disconnecting an edge with user defined junctions at its end points will result in orphan junctions at the end points. Note that if orphan junctions are at the edge end points; new orphan junctions will not be created. Disconnecting an edge which has junctions that are only connected at mid-span along the edge will not result in the creation of an orphan junction.
The following diagram demonstrates how Disconnect works in certain situations; the dashed arrow indicates on which feature Disconnect is being used:
The Connect and Disconnect commands are designed to complement each other and should be used for transitory editing workflows which will be completed within a given edit session. You can think of them as bookends; used to start and end a workflow. Some examples of these kinds of workflows are:
- Moving a feature without moving the features to which it is connected
- Repositioning a junction or an edge along an existing edge
- Inserting an edge feature between two existing network features.
The general workflow for these edits is to disconnect the feature, perform the edit, and connect the feature. Keep in mind that disconnecting a feature is designed to be a temporary situation. Since the geometric network determines connectivity based on geometric coincidence, disconnected features may become connected during editing, such as when a new feature is created coincident to a disconnected feature, or when performing a reconcile operation in which a feature is inserted coincident with the disconnected feature.
Other things to note about he Disconnect and Connect commands are:
- Each works on the entire edge feature; not a section of the edge feature
- It is not possible to Disconnect or Connect one end point of an edge, but not the other end point. Connect and Disconnect work on the entire feature.
Summary
The Connect and Disconnect commands can be used to improve your editing experience with network features; but using them does require an understanding of rules that govern geometric network editing; which is available in the About editing geometric network features topic . I’ve gone over some examples of when Connect and Disconnect can and should be used and what to be aware of when using these commands.