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Traversing and Modifying a Node Hierarchy

A Wiretap server uses a hierarchy of nodes to represent the directory structure of an underlying database. These workflows are related to navigating the node hierarchy and to modifying it in generic ways (copy, modify, delete). The WireTapNodeHandle class is important in these workflows.

Viewing the Node Hierarchy of a Wiretap Server

Related C++ Sample

  • listChildren.C

Related Python Sample

  • listChildren.py

Related Command Line Tools

  • wiretap_get_root_node
  • wiretap_get_children
  • wiretap_print_tree

See Understanding the IFFFS Wiretap Server Node Hierarchy for the structure and description of the IFFFFS Wiretap server hierarchy.

Node Handles

The WireTapNodeHandle class represents a node in a Wiretap server hierarchy.

The fact that a Wiretap client can manipulate objects on a Wiretap server resembles Microsoft’s Component Object Model (COM). Unlike COM objects, Wiretap node handles are not automatically updated when there is a change in the object they point to on the server. If the Wiretap client requires the latest state of an object on the server, it must update the information explicitly by calling the appropriate accessor method on the node handle.

Node IDs

Each node has a node ID. These methods give access to the node IDs of a Wiretap server:

  • WireTapNodeHandle.getNodeId() – Returns a WireTapNodeId object.
  • WireTapNodeId.id() – Returns a string containing the persistent ID of a node.

Responsibility of Wiretap Servers with Respect to IDs

In addition to node IDs, other Wiretap entities have IDs: servers, storage devices, and frames. Wiretap servers are responsible for ensuring the persistence and uniqueness of:

  • Server IDs (network-based server identification)
  • Node IDs
  • Storage IDs (persistent and network-independent server identification)
  • Host UUID

Wiretap servers do not guarantee the uniqueness and persistence of frame IDs.

You should not persist connection information based on the server ID: this ID can change over time, such as when the network uses DHCP. Instead, use the server ID for the first connection and get either Storage ID or Host UUID, and then use either for the following connections.

Creating Nodes

Related C++ Samples

  • createClip.C
  • createProject.C
  • createUser.C

Related Python Sample

  • createClip.py

Related Command Line Tool

  • wiretap_create_node
  • wiretap_duplicate_node

The WireTapNodeHandle class includes a number of methods for creating nodes and clip nodes. Use WireTapNodeHandle.createNode to create all types of nodes (except clip nodes).

Getting and Setting Node Metadata

Related C++ Sample

  • createProject.C

Related Command Line Tools

  • wiretap_get_metadata
  • wiretap_set_metadata

To get and set the metadata for a node, you call the getMetaData and setMetaData methods on the WireTapNodeHandle object. Metadata is a stream that can be in any format (for example, XML).

Note: The node hierarchy is automatically saved 2 seconds after the last operation in Wiretap. To force a save and avoid having to wait before reading back the information, perform a wiretap_set_metadata -commit on the parent catalog node.

For more information about the metadata that can be set on a particular type of node, see:

Deleting Nodes

Related C++ Sample

  • destroyNodeHierarchy.C

Related Command Line Tool

  • wiretap_destroy_node

To delete a node, you call the destroyNode method on the WireTapNodeHandle object.

Depending on the type of node, there may be some conditions on deleting a node. For more information, see:

Parent page: Programming Typical Workflows

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