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    <p>Yes, that is possible, but not the way you'd expect.</p> <p>You can <strong>not</strong> have a (non launchd) process vend a service. That is for security reasons, since it would make it easy to do man-in-the-middle attacks.</p> <p>You can still achieve what you want, though: You have to set up a launchd service that vends an XPC / mach service. Both process A and B then connect to your launchd service. Process A can then create a so called <strong>anonymous connection</strong> and send that to the launchd service which will forward it to process B. Once that has happened, processes A and B can talk to each other directly through that connection (i.e. the launchd service can exit without the connection breaking).</p> <p>This may seem round-about, but it's necessary for security reasons.</p> <p>See the <code>xpc_object(3)</code> man page for details about anonymous connections.</p> <p>It's a bit counter intuitive, because process A will create a <em>listener</em> object with <code>xpc_connection_create()</code>. A then creates an <em>endpoint</em> object from the listener with <code>xpc_endpoint_create()</code> and sends that endpoint across the wire (over XPC) to process B. B can then turn that object into a connection with <code>xpc_connection_create_from_endpoint()</code>. A's event handler for the <em>listener</em> will then receive a connection object matching the connection that B created with <code>xpc_connection_create_from_endpoint()</code>. This works similar to the way that the event handler of <code>xpc_connection_create_mach_service()</code> will receive connection objects when clients connect.</p>
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    1. POIs possible to use Mac OS X XPC like IPC to exchange messages between processes? How?
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    1. USDaniel Eggert
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    1. COWhat if I don't want process B to connect to the service? Assume, for example, that B is a bash script or an already compiled C program, is it then possible to achieve "classic" IPC through XPC? Or, alternatively, may I bypass XPC in some way (using `NSPipe` or something like that)?
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    2. COYou don't have to use XPC, but if you're using XPC, you're using XPC. You can write an XPC client that you can execute from the command line, though, if you need that. Hard to say what the best solution is without more details.
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    3. COMaybe it's not nice to ask explicitly but here's my question if you mind to take a look: http://stackoverflow.com/questions/9742937/interprocess-communication-on-macosx-lion
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