The beam.py example program uses the Simple NDEF Exchange Protocol (SNEP) to send or receive NDEF messages to or from a peer device, in most cases this will be a smartphone. The name beam is inspired by Android Beam and thus beam.py will be able to receive most content sent through Android Beam. It will not work for data that Android Beam sends with connection handover to Bluetooth or Wi-Fi, this may become a feature in a later version. Despite it's name, beam.py works not only with Android phones but any NFC enabled phone that implements the NFC Forum Default SNEP Server, such as Blackberry and Windows Phone 8. :
$ beam.py [-h|--help] [OPTIONS] {send|recv} [-h] [OPTIONS]beam.py
Send an NDEF message to the peer device. The message depends on the positional argument that follows the send command and additional data. :
$ beam.py send [--timeit] {link,text,file,ndef} [-h] [OPTIONS]beam.py send
--timeit
Measure and print the time that was needed to send the message.
Send a hyperlink embedded into a smartposter record. :
$ beam.py send link URI [TITLE]beam.py send link
URI
The resource identifier, for example http://nfcpy.org.
TITLE
The smartposter title, for example "nfcpy project home".
Send plain text embedded into an NDEF Text Record. The default language identifier en can be changed with the --lang flag. :
$ beam.py send text TEXT [OPTIONS]beam.py send text
TEXT
The text string to send.
--lang STRING
The language code to use when constructing the NDEF Text Record.
Send a data file. This will construct a single NDEF record with type and name set to the file's mime type and path name, and the payload containing the file content. Both record type and name can also be explicitly set with the options -t and -n, respectively. :
$ beam.py send file FILE [OPTIONS]beam.py send file
FILE
The file to send.
-t STRING
Set the record type. See /topics/ndef for how to specify record types in nfcpy.
-n STRING
Set the record name (identifier).
Send an NDEF message read from file. The file may contain multiple messages and if it does, then the strategy to select a specific message for sending can be specified with the --select STRATEGY option. For strategies that select a different message per touch beam.py must be called with the --loop flag. The strategies first, last and random select the first, or last, or a random message from FILE. The strategies next and cycle start with the first message and then count up, the difference is that next stops at the last message while cycle continues with the first. :
$ beam.py send ndef FILE [OPTIONS]beam.py send ndef
FILE
The file from which to read NDEF messages.
--select STRATEGY
The strategy for NDEF message selection, it may be one of first, last, next, cycle, random.
Receive an NDEF message from the peer device. The next positional argument determines what is done with the received message. :
$ beam.py [OPTIONS] recv {print,save,echo,send} [-h] [OPTIONS]Print the received message to the standard output stream. :
$ beam.py recv printbeam.py recv print
Save the received message into a file. If the file already exists the message is appended. :
$ beam.py recv save FILEbeam.py recv file
FILE
Name of the file to save messages received from the remote peer. If the file exists any new messages are appended.
Receive a message and send it back to the peer device. :
$ beam.py recv echobeam.py recv echo
Receive a message and send back a corresponding message if such is found in the translations file. The translations file must contain an even number of NDEF messages which are sequentially read into inbound/outbound pairs to form a translation table. If the receved message corresponds to any of the translation table inbound messages the corresponding outbound message is then sent back. :
$ beam.py [OPTIONS] recv send [-h] TRANSLATIONSbeam.py recv send
TRANSLATIONS
A file with a sequence of NDEF messages.
Get a smartphone to open the nfcpy project page (which in fact just points to the code repository and documentation). :
$ beam.py send link http://nfcpy.org "nfcpy project home"Send the source file beam.py. On an Android phone this should pop up the "new tag collected" screen and show that a text/x-python media type has been received. :
$ beam.py send file beam.pyThe file beam.py is about 11 KB and may take some time to transfer, depending on the phone hardware and software. With a Google Nexus 10 it takes as little as 500 milliseconds while a Nexus 4 won't do it under 2.5 seconds. :
$ beam.py send --timeit file beam.pyReceive a single NDEF message from the peer device and save it to message.ndef (note that if message.ndef exists the received data will be appended): :
$ beam.py recv save message.ndefWith the --loop option it gets easy to collect messages into a single file. :
$ beam.py --loop recv save collected.ndefA file that contains a sequence of request/response message pairs can be used to send a specific response message whenever the associated request message was received. :
$ echo -n "this is a request message" > request.txt
$ ndeftool.py pack -n '' request.txt -o request.ndef
$ echo -n "this is my reponse message" > response.txt
$ ndeftool.py pack -n '' response.txt -o response.ndef
$ cat request.ndef response.ndef > translation.ndef
$ beam.py recv send translation.ndef