| … | |
… | |
| 762 | aemp run profile seed |
762 | aemp run profile seed |
| 763 | |
763 | |
| 764 | And then you can experiment with chatting, killing one or more clients, or |
764 | And then you can experiment with chatting, killing one or more clients, or |
| 765 | stopping and restarting the server, to see the monitoring in action. |
765 | stopping and restarting the server, to see the monitoring in action. |
| 766 | |
766 | |
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767 | The crucial point you should understand from this example is that |
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768 | monitoring is usually symmetric: when you monitor some other port, |
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769 | potentially on another node, that other port usually should monitor you, |
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770 | too, so when the connection dies, both ports get killed, or at least both |
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771 | sides can take corrective action. Exceptions are "servers" that serve |
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772 | multiple clients at once and might only wish to clean up, and supervisors, |
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773 | who of course should not normally get killed (unless they, too, have a |
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774 | supervisor). |
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775 | |
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776 | If you often think in object-oriented terms, then treat a port as an |
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777 | object, C<port> is the constructor, the receive callbacks set by C<rcv> |
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778 | act as methods, the C<kil> function becomes the explicit destructor and |
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779 | C<mon> installs a destructor hook. Unlike conventional object oriented |
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780 | programming, it can make sense to exchange ports more freely (for example, |
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781 | to monitor one port from another). |
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782 | |
| 767 | There is ample room for improvement: the server should probably remember |
783 | There is ample room for improvement: the server should probably remember |
| 768 | the nickname in the C<join> handler instead of expecting it in every chat |
784 | the nickname in the C<join> handler instead of expecting it in every chat |
| 769 | message, it should probably monitor itself, and the client should not try |
785 | message, it should probably monitor itself, and the client should not try |
| 770 | to send any messages unless a server is actually connected. |
786 | to send any messages unless a server is actually connected. |
| 771 | |
787 | |
