HTTP-Enabled Location Delivery (HELD)

A Device uses the HTTP-Enabled Location Delivery (HELD) protocol to  retrieve its location either directly in the form of a Presence Information Data Format Location Object (PIDF-LO) document(by value) or indirectly as a Location URI (by reference). This section describes how HELD can be used to dereference a location URI.  This process can be applied when a Location Recipient is in possession of a location URI with an "https:" or "http:" URI scheme.

• Location Request : A location request message is sent from the Device to the LIS when the Device requires its own LI.  The type of LI that a Device  requests is determined by the type of LI that is included in the  "locationType" element. The location request is made by sending a document formed of a  "locationRequest" element.  The LIS uses the source IP address of the location request message as the primary source of identity for the requesting Device or target.  It is anticipated that other Device identities may be provided through schema extensions.
• Location Response : A successful response to a location request MUST contain a PIDF-LO and/or Location URI(s).  The response SHOULD contain location information of the requested" locationType".  

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