REST Interface for Edges {#RestEdge}
====================================

@NAVIGATE_RestEdge
@EMBEDTOC{RestEdgeTOC}

This is an introduction to ArangoDB's REST interface for edges.

ArangoDB offers also some graph functionality. A graph consists of nodes, edges
and properties. ArangoDB stores the information how the nodes relate to each
other aside from the properties.

A graph data model always consists of two collections: the relations between the
nodes in the graphs are stored in an "edges collection", the nodes in the graph
are stored in documents in regular collections.

Example:
- the "edge" collection stores the information that a company's reception is
  sub-unit to the services unit and the services unit is sub-unit to the
  CEO. You would express this relationship with the @LIT{_from} and
  `_to` property
- the "normal" collection stores all the properties about the reception,
  e.g. that 20 people are working there and the room number etc.
- `_from` is the document handle of the linked vertex (incoming relation),
- `_to` is the document handle of the linked vertex (outgoing relation).

Documents, Identifiers, Handles {#RestEdgeIntro}
================================================

@copydoc GlossaryEdge

Address and ETag of an Edge {#RestEdgeResource}
===============================================

All documents in ArangoDB have a document handle. This handle uniquely defines a
document and is managed by ArangoDB. All documents are found under the URI

    http://server:port/_api/document/document-handle

For edges you can use the special address

    http://server:port/_api/edge/document-handle

For example: Assume that the document handle, which is stored in the `_id`
attribute of the edge, is `demo/362549736`, then the URL of that edge is:

    http://localhost:8529/_api/edge/demo/362549736

Working with Edges using REST {#RestEdgeHttp}
=============================================

@anchor RestEdgeRead
@RESTHEADER{GET /_api/edge,reads an edge}

@REST{GET /_api/edge/@FA{document-handle}}

See @ref RestDocument for details.

@anchor RestEdgeCreate
@copydetails triagens::arango::RestEdgeHandler::createDocument

@anchor RestEdgeUpdate
@RESTHEADER{PUT /_api/edge,updates an edge}

@REST{PUT /_api/edge/@FA{document-handle}}

See @ref RestDocument for details.

@anchor RestEdgeDelete
@RESTHEADER{DELETE /_api/edge,deletes an edge}

@REST{DELETE /_api/edge/@FA{document-handle}}

See @ref RestDocument for details.

@anchor RestEdgeHead
@RESTHEADER{GET /_api/edge,reads an edge header}

@REST{HEAD /_api/edge/@FA{document-handle}}

See @ref RestDocument for details.

@anchor RestEdgeEdges
@copydetails JSF_GET_edges