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68 lines
3.0 KiB
68 lines
3.0 KiB
14 years ago
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One of the greatest assets of the Palm Pilot is its ability to
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interconnect with other applications. KPilot supports this capabilty
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through conduits. A conduit is a small shared library that is loaded by
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the daemon during the hot sync. The conduit translates between the Palm
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Pilot and the application you're syncing with.
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*** How it works
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KPilot is divided into three major components: the GUI, the
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syncing daemon, and the conduits. The GUI part is actually irrelevant
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for the operation of the daemon, although it _is_ required for the
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configuration dialog (and possibly viewing databases). In theory
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you could run the daemon on a box without even starting X, although
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that is difficult (in particular, how would you do conflict resolution?).
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The daemon sits around and polls the configured device every second or
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so (there are devices where this should be more often, I think). Once
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data arrives (and the device exists, consider hotplug with USB), the
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daemon enters sync mode, and constructs a queue of SyncActions to perform.
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These vary from checking the Pilot's username to performing full backups
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to -- whatever sync actions the conduits provide. This means that during
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a sync the shared library containing a conduit is loaded, a factory
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function is called to produce an Action, this action is run, and the
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library unloaded.
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*** How the conduits work
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The conduits can actually be divided into two parts: the configuration
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widget, and the Action. Both are produced by a factory function in
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the shared library. The conduits have only one really interesting method
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that they must override, and that is exec(). When this is called the
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conduit is already set up with a socket descriptor and the conduit should
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quickly do its thing. In particular, conduits can't just sleep(45) and
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continue, since the connection with the Pilot will time out.
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*** Write your very own conduit
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Writing a conduit is actually rather easy. The conduit class
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should inherit from ConduitAction and override the exec() method
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(which actually comes from SyncAction).
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*** Debugging things
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lib/options.h contains two defines that are really important for
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debugging. These are
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// #define DEBUG (1)
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// #define DEBUG_CERR (1)
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Uncommenting DEBUG will enable most of the debug information in
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KPilot. Uncommenting DEBUG_CERR will make debug output go direct
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to stderr (cerr) instead of through kdDebug. If in addition, you
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pass --debug N (say, N=1 or N=4) to KPilot or the daemon when you
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start them, they will print call traces (that's what FUNCTIONSETUP
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does, which you will see at the beginning of every function).
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Another useful tool is kpilotTest, which is in kpilot/kpilot. It
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is an uninstalled binary, which behaves like the daemon with a
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log window and which will run a single conduit. Something like:
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kpilotTest -p /dev/ucom0 \ # port
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-E conduit_knotes \ # .desktop file
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-T # _really_ run
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use kpilotTest -L to list the installed conduits and their
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desktop files (look at the "In ..." lines).
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