@ndn/cat

This package is part of NDNts, Named Data Networking libraries for the modern web.

ndncat is a command line utility to publish and retrieve objects in various formats.

Publish and Retrieve Segmented Object

ndncat put-segmented publishes a segmented object, reading payload from standard input. It accepts the following arguments:

• Positional argument: name prefix.
• NDNTS_UPLINK, NDNTS_NFDREG, NDNTS_KEYCHAIN, NDNTS_KEY environment variables, as explained in @ndn/cli-common package.
• --convention=R encodes version and segment components in revR format (default is rev3).
• --ver=42 inserts a specific version number as version component.
• --ver=now (default) inserts current timestamp as version component.
• --ver=none omits version component.
• --no-rdr disables publishing current version as a RDR metadata packet. This is ignored with --ver=none.
• --file=FILE reads from a file instead of standard input.
• --chunk-size=N sets segment payload size.

ndncat get-segmented retrieves a segmented object, writing payload to standard output. It accepts the following arguments:

• Positional argument: name prefix.
• NDNTS_UPLINK environment variable, as explained in @ndn/cli-common package.
• --convention=R encodes version and segment components in revR format (default is rev3).
• --ver=42 inserts a specific version number as version component.
• --ver=none disables version discovery and assumes Data has no version component.
• --ver=cbp sends Interest with CanBePrefix and MustBeFresh to discover version.
• --ver=rdr (default) sends an RDR discovery Interest to discover version.

Example

# generate test file
dd if=/dev/urandom of=/tmp/1.bin bs=1M count=1

# run one of the producer command and one of the consumer commands

# producer: serve from stdin
ndncat put-segmented /A </tmp/1.bin

# producer: serve from file, 8KB chunks
ndncat put-segmented /A --file=/tmp/1.bin --chunk-size=8192

# producer: use ndnputchunks from ndn-tools
ndnputchunks /A </tmp/1.bin

# consumer: perform version discovery via RDR protocol
ndncat get-segmented /A >/tmp/2.bin

# consumer: perform version discovery via CanBePrefix
ndncat get-segmented --ver=cbp /A >/tmp/2.bin

# consumer: use ndncatchunks from ndn-tools
ndncatchunks /A >/tmp/2.bin

# compare and delete test file
diff /tmp/1.bin /tmp/2.bin
rm /tmp/1.bin /tmp/2.bin

Download Files and Folders

ndncat file-client downloads files and folders served from ndn6-file-server. It accepts the following arguments:

• Positional arguments: remote name prefix, local file directory.
• NDNTS_UPLINK environment variable, as explained in @ndn/cli-common package.
• --jobs=4 sets number of parallel downloads.
• --retx=10 sets Interest retransmission limit.

The remote name prefix must refer to a folder. This command recursively downloads files and folders contained within. If you want to download an individual file, use ndncat get-segmented command instead.

Example

ndn6-file-server /demo/file-server /usr/include/linux

ndncat file-client /demo/file-server /tmp/file-client-demo