Class for RDR-style metadata encoding/decoding. More...

#include <metadata-object.hpp>

Classes
class	Error

Public Member Functions
	MetadataObject ()
	Create an empty metadata object. More...

	MetadataObject (const Data &data)
	Construct a metadata object by decoding of the given Data packet. More...

NDN_CXX_NODISCARD Data	makeData (Name discoveryInterestName, KeyChain &keyChain, const ndn::security::SigningInfo &si=security::SigningInfo(), optional< uint64_t > version=nullopt, time::milliseconds freshnessPeriod=10_ms) const
	Create a Data packet representing this metadata object. More...

const Name &	getVersionedName () const
	Return the versioned name (i.e., the name inside the content) More...

MetadataObject &	setVersionedName (const Name &name)
	Set the versioned name. More...

Static Public Member Functions
static const name::Component &	getKeywordComponent ()
	Returns the well-known keyword name component used for metadata objects (`32=metadata`) More...

static bool	isValidName (const Name &name)
	Check whether `name` can be a valid metadata name. More...

static NDN_CXX_NODISCARD Interest	makeDiscoveryInterest (Name name)
	Generate a discovery interest packet based on `name`. More...

Detailed Description

Class for RDR-style metadata encoding/decoding.

Realtime Data Retrieval (RDR) is a protocol for discovering the latest version number of a given data collection. The Interest and Data packets dealing with metadata (called "discovery interest" and "metadata object", respectively) follow a specific format.

There are two names in an RDR metadata object:

the versioned name is a prefix of the data collection, and generally contains a version component. It appears in the Content element of the metadata object.
the metadata name is the name of the metadata object itself, and includes a keyword name component 32=metadata, as well as version and segment components.

See also: https://redmine.named-data.net/projects/ndn-tlv/wiki/RDR

Definition at line 48 of file metadata-object.hpp.

Constructor & Destructor Documentation

◆ MetadataObject() [1/2]

ndn::MetadataObject::MetadataObject ( )

default

Create an empty metadata object.

◆ MetadataObject() [2/2]

ndn::MetadataObject::MetadataObject ( const Data & data )

explicit

Construct a metadata object by decoding of the given Data packet.

Exceptions

tlv::Error the Data is not a valid metadata packet

Definition at line 33 of file metadata-object.cpp.

References ndn::tlv::ContentType_Blob, ndn::Block::get(), ndn::Data::getContent(), ndn::Data::getContentType(), ndn::Data::getName(), isValidName(), ndn::tlv::Name, NDN_THROW, ndn::Block::parse(), ndn::to_string(), ndn::Name::toUri(), ndn::Block::value_size(), and ndn::Name::wireDecode().

Member Function Documentation

◆ makeData()

Data ndn::MetadataObject::makeData	(	Name	discoveryInterestName,
		KeyChain &	keyChain,
		const ndn::security::SigningInfo &	si = `security::SigningInfo()`,
		optional< uint64_t >	version = `nullopt`,
		time::milliseconds	freshnessPeriod = `10_ms`
	)		const

Create a Data packet representing this metadata object.

Parameters

discoveryInterestName	the discovery Interest's name, which must end with a keyword name component `32=metadata`
keyChain	KeyChain to sign the Data
si	signing parameters
version	version number of metadata packet; if nullopt, use current Unix timestamp (in milliseconds) as the version number
freshnessPeriod	freshness period of metadata packet

Exceptions

tlv::Error discoveryInterestName is not valid

Definition at line 53 of file metadata-object.cpp.

References ndn::Name::appendSegment(), ndn::Name::appendVersion(), ndn::Name::empty(), getKeywordComponent(), NDN_THROW, ndn::Data::setContent(), ndn::Data::setFreshnessPeriod(), ndn::Name::toUri(), and ndn::Name::wireEncode().

◆ getVersionedName()

const Name& ndn::MetadataObject::getVersionedName ( ) const

inline

Return the versioned name (i.e., the name inside the content)

Definition at line 93 of file metadata-object.hpp.

References getKeywordComponent(), isValidName(), makeDiscoveryInterest(), NDN_CXX_NODISCARD, and setVersionedName().

◆ setVersionedName()

MetadataObject & ndn::MetadataObject::setVersionedName ( const Name & name )

Set the versioned name.

Any metadata packet carries a versioned name in its payload where it shows the name and the latest version of a data stream. For instance, /ndn/test/v=2538020460 is a versioned name that shows the latest version of /ndn/test.

Definition at line 75 of file metadata-object.cpp.

Referenced by getVersionedName().