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110 lines
4.2 KiB
Plaintext
110 lines
4.2 KiB
Plaintext
Asterisk External IVR Interface
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-------------------------------
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If you load app_externalivr.so in your Asterisk instance, you will
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have an ExternalIVR() application available in your dialplan. This
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application implements a simple protocol for bidirectional
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communication with an external process, while simultaneous playing
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audio files to the connected channel (without interruption or
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blocking).
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The arguments to ExternalIVR() consist of the command to execute and
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any arguments to pass to it, the same as the System() application
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accepts. The external command will be executed in a child process,
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with its standard file handles connected to the Asterisk process as
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follows:
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stdin (0) - DTMF and hangup events will be received on this handle
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stdout (1) - Playback and hangup commands can be sent on this handle
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stderr (2) - Error messages can be sent on this handle
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The application will also create an audio generator to play audio to
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the channel, and will start playing silence. When your application
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wants to send audio to the channel, it can send a command (see below)
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to add file(s) to the generator's playlist. The generator will then
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work its way through the list, playing each file in turn until it
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either runs out of files to play, the channel is hung up, or a command
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is received to clear the list and start with a new file. At any time,
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more files can be added to the list and the generator will play them
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in sequence.
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While the generator is playing audio (or silence), any DTMF events
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received on the channel will be sent to the child process (see
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below). Note that this can happen at any time, since the generator,
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the child process and the channel thread are all executing
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independently. It is very important that your external application be
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ready to receive events from Asterisk at all times (without blocking),
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or you could cause the channel to become non-responsive.
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If the child process dies, ExternalIVR() will notice this and hang up
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the channel immediately (and also send a message to the log).
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DTMF (and other) events
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-----------------------
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All events will be newline-terminated strings.
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Events send to the child's stdin will be in the following format:
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tag,timestamp[,data]
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The tag can be one of the following characters:
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0-9: DTMF event for keys 0 through 9
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A-D: DTMF event for keys A through D
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*: DTMF event for key *
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#: DTMF event for key #
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H: the channel was hung up by the connected party
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Z: the previous command was unable to be executed (file does not
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exist, etc.)
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T: the play list was interrupted (see below)
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D: a file was dropped from the play list due to interruption (the
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data element will be the dropped file name)
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F: a file has finished playing (the data element will be the file
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name)
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The timestamp will be 10 digits long, and will be a decimal
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representation of a standard Unix epoch-based timestamp.
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Commands
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--------
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All commands must be newline-terminated strings.
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The child process can send commands on stdout in the following formats:
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S,filename
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A,filename
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H,message
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O,option
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The 'S' command checks to see if there is a playable audio file with
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the specified name, and if so, clear's the generator's playlist and
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places the file onto the list. Note that the playability check does
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not take into account transcoding requirements, so it is possible for
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the file to not be played even though it was found. If the file cannot
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be found, a 'Z' event (see above) will be sent to the child. If the
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generator is not currently playing silence, then T and D events will
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be sent to the child to signal the playlist interruption and notify
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it of the files that will not be played.
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The 'A' command checks to see if there is a playable audio file with
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the specified name, and if so, adds it to the generator's
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playlist. The same playability and exception rules apply as for the
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'S' command.
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The 'H' command stops the generator and hangs up the channel, and logs
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the supplied message to the Asterisk log.
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The 'O' command allows the child to set/clear options in the
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ExternalIVR() application. The supported options are:
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autoclear/noautoclear:
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Automatically interrupt and clear the playlist upon reception
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of DTMF input.
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Errors
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------
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Any newline-terminated output generated by the child process on its
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stderr handle will be copied into the Asterisk log.
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