.. _packetFormat:

Query

Requests to the server are made in the format of a standard NDN interest packet. The question is replaced with a standard request for content.

See :ref Interest section <Interest> for details.

Answer

.. _data: Data ::= DATA-TLV TLV-LENGTH Name MetaInfo Content Signature

Every response from the NDNS system comes in the same generic form. The specialization is accomplished by setting values in the MetaInfo structure.

Name

See :ref:`Name section <Name>` for details.

.. _MetaInfo


MetaInfo

MetaInfo specified here represents portions that are defaultly specified in any NDN packet, which NDNS specific additions.

See NDN Packet Specification - Meta-Info <http://named-data.net/doc/ndn-tlv/data.html#metainfo>_

MetaInfo ::= META-INFO-TYPE TLV-LENGTH ContentType FreshnessPeriod? NDNS-Type AnswerCount

ContentType +++++++++++

::

    ContentType ::= CONTENT-TYPE-TYPE TLV-LENGTH 
                  nonNegativeInteger

For an NDNS packet the ContentType should always be BLOB (=0), specificity is accomplished by NDNS-Type.

See :ref: NDNS-Type for details

FreshnessPeriod +++++++++++++++

::

    FreshnessPeriod ::= FRESHNESS-PERIOD-TLV TLV-LENGTH 
                      nonNegativeInteger

The optional freshness period specifies how long after the arrive of the data the recieving node should wait before marking it stale.

See NDN Packet Specification - Freshness Period <http://named-data.net/doc/ndn-tlv/data.html#freshnessperiod>_

.. _NDNS-Type:

NDNS-Type +++++++++

::

    NDNS-Type ::= NDNS-TYPE-TLV TLV-LENGTH
                nonNegativeIntegear

There are 3 distinct types of NDNS Responses: +-----------+------------------------------------------------------------------+ | Type | Description | +===========+==================================================================+
| NDNS Data | indicates an answer was found, and that contains the requested | | | content | +-----------+----------------------------------------------------------------+
| NDNS NACK | indicates that the responding zone has no content matching the | | | query. | +-----------+------------------------------------------------------------------+ | NDNS AUTH | indicates that the zone has content, but a more specific | | | question is need to determine the correct content to server. | +-----------+------------------------------------------------------------------+

.. note:

Both NDNS NACK and NDNS AUTH are types of negative respones which indicate an issue with the request.

.. _AnswerCount:

AnswerCount ++++++++++++

::

        AnswerCount ::= ANSWER-COUNT-TLV TLV-LENGTH
                nonNegativeIntegear

This field is used to specify the number of answer in a response.

Content

::

            Content ::= CONTENT-TYPE TLV-LENGTH BYTE*
            
Signature

::

        Signature ::= SignatureInfo
                      SignatureBits

See NDN Signature Specification - Signature <http://named-data.net/doc/ndn-tlv/signature.html>_