Tree Pattern

Trees represent real-world structures like directories, navigations, org charts and other hierarchies. Relationships bind the nodes of a tree together and give them context with the other nodes.

The Nodes in a tree have one parent link to their parent Node as well as a top link to the Tree. Top-level Nodes, those that are direct children of Tree, do not have a parent link. Nodes that have no child links are considered leaves.

Tree Resource

Profile: <http://level3.rest/patterns/tree#tree-resource>

The Tree resource presents either the Info or Nexus profile.

If the Tree resource presents the Nexus profile, then it can be deleted with a DELETE operation. The node resources in the tree are also deleted. For instance, if the tree represents a file system, then deleting the Tree resource also deletes the child file and directory resources because the individual files have no context to exist outside of their directory.

The Tree resource shares the child relationship with Node resource.

Node Resource

Profile: <http://level3.rest/patterns/tree#node-resource>

A Node resource has no required profile. If the node’s profile supports the DELETE operation, a client can remove the node from the tree by deleting the node. This operation deletes all child nodes and their children as well.

top

rel="http://level3.rest/patterns/tree#top"

The top link points to the Tree of which the node is a member.

child

rel="http://level3.rest/patterns/tree#child"

Tree and Node resources have 0 or more child links pointing to direct child Node resources. The ordering of the links is intentional, meaning they should be considered the sibling order. HTTP header sequence rules ensure the client can rely on this order to be consistent with the resource’s ordering intentions.

parent

rel="http://level3.rest/patterns/tree#parent"

The parent link points to the node’s parent Node.

Specifications

HTTP/1.1 Message Syntax and Routing: RFC 7230


Copyright © 2019 Matt Bishop
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