| 1 | The code here demonstrates the use of INDI, an Instrument-Neutral Device
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| 2 | Interface protocol. See http://www.clearskyinstitute.com/INDI/INDI.pdf.
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| 3 |
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| 4 | Architecture:
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| 5 |
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| 6 | Typical INDI Client / Server / Driver / Device connectivity:
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| 7 |
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| 8 |
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| 9 | INDI Client 1 ----| |---- INDI Driver A ---- Dev X
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| 10 | | |
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| 11 | INDI Client 2 ----| |---- INDI Driver B ---- Dev Y
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| 12 | | | |
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| 13 | ... |--- indiserver ---| |-- Dev Z
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| 14 | | |
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| 15 | | |
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| 16 | INDI Client n ----| |---- INDI Driver C ---- Dev T
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| 17 |
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| 18 |
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| 19 | Client INET Server UNIX Driver Hardware
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| 20 | processes sockets process pipes processes devices
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| 21 |
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| 22 |
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| 23 |
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| 24 | Indiserver is the public network access point where one or more INDI Clients
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| 25 | may contact one or more INDI Drivers. Indiserver launches each driver
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| 26 | process and arranges for it to receive the INDI protocol from Clients on
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| 27 | its stdin and expects to find commands destined for Clients on the
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| 28 | driver's stdout. Anything arriving from a driver process' stderr is copied
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| 29 | to indiserver's stderr.
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| 30 |
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| 31 | Indiserver only provides convenient port, fork and data steering services.
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| 32 | If desired, a Client may run and connect to INDI Drivers directly.
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| 33 |
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| 34 | Construction:
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| 35 |
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| 36 | An INDI driver typically consists of one .c file, eg, mydriver.c, which
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| 37 | #includes indiapi.h to access the reference API declarations. It is
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| 38 | compiled then linked with indidrivermain.o, eventloop.o and liblilxml.a to
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| 39 | form an INDI process. These supporting files contain the implementation of
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| 40 | the INDI Driver API and need not be changed in any way. Note that
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| 41 | evenloop.[ch] provide a nice callback facility independent of INDI which
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| 42 | may be used in other projects if desired.
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| 43 |
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| 44 | The driver implementation, again in our example mydriver.c, does not
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| 45 | contain a main() but is expected to operate as an event-driver program.
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| 46 | The driver must implement each ISxxx() function but never call them. The
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| 47 | IS() functions are called by the reference implementation main() as messages
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| 48 | arrive from Clients. Within each IS function the driver performs the
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| 49 | desired tasks then may report back to the Client by calling the IDxxx()
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| 50 | functions.
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| 51 |
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| 52 | The reference API provides IE() functions to allow the driver to add its
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| 53 | own callback functions if desired. The driver can arrange for functions to
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| 54 | be called when reading a file descriptor will not block; when a time
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| 55 | interval has expired; or when there is no other client traffic in progress.
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| 56 |
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| 57 | The sample indiserver is a stand alone process that may be used to run one
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| 58 | or more INDI-compliant drivers. It takes the names of each driver process
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| 59 | to run in its command line args.
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| 60 |
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| 61 | To build indiserver type 'make indiserver';
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| 62 | to build all the sample drivers type 'make drivers';
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| 63 | to run the sample server with all drivers type 'make run'.
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| 64 | Killing indiserver will also kill all the drivers it started.
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| 65 |
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| 66 | Secure remote operation:
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| 67 |
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| 68 | Suppose we want to run indiserver and its clients on a remote machine, r,
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| 69 | and connect them to our favorite INDI client, XEphem, running on the
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| 70 | local machine.
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| 71 |
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| 72 | From the local machine log onto the remote machine, r, by typing:
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| 73 |
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| 74 | ssh2 -L 7624:s:7624 r
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| 75 |
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| 76 | after logging in, run indiserver on the remote machine:
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| 77 |
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| 78 | make run
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| 79 |
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| 80 | Back on the local machine, start XEphem, then open Views -> Sky View ->
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| 81 | Telescope -> INDI panel. XEphem will connect to the remote INDI server
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| 82 | securely and automatically begin running. Sweet.
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| 83 |
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| 84 | Testing:
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| 85 |
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| 86 | A low-level way to test the socket, forking and data steering abilities of
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| 87 | indiserver is to use the 'hose' command from the netpipes collection
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| 88 | (http://web.purplefrog.com/~thoth/netpipes/netpipes.html):
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| 89 |
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| 90 | 1. start indiserver using UNIX' cat program as the only INDI "device":
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| 91 |
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| 92 | % indiserver cat &
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| 93 |
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| 94 | 2. use hose to connect to the "cat" device driver which just copies back:
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| 95 |
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| 96 | % hose localhost 7624 --slave
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| 97 | hello world
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| 98 | hello world
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| 99 | more stuff
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| 100 | more stuff
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| 101 |
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| 102 | ! For RCS Only -- Do Not Edit
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| 103 | ! @(#) $RCSfile$ $Date: 2004-02-03 09:34:32 +0300 (Tue, 03 Feb 2004) $ $Revision: 284704 $ $Name: $
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