==============
Monitor Server
==============
The monitor server is a server that provides a command-line interface to
request various bits of information. The server is zc.ngi based, so we can use
the zc.ngi testing infrastructure to demonstrate it.
>>> import zc.ngi.testing
>>> import zc.monitor
>>> connection = zc.ngi.testing.TextConnection()
>>> server = zc.monitor.Server(connection)
The server supports an extensible set of commands. It looks up
commands as named zc.monitor.interfaces.IMonitorPlugin "utilities", as defined
by the zope.component package.
To see this, we'll create a hello plugin:
>>> def hello(connection, name='world'):
... """Say hello
...
... Provide a name if you're not the world.
... """
... connection.write("Hi %s, nice to meet ya!\n" % name)
and register it:
>>> zc.monitor.register(hello)
When we register a command, we can provide a name. To see this, we'll
register ``hello`` again:
>>> zc.monitor.register(hello, 'hi')
Now we can give the hello command to the server:
>>> connection.test_input('hi\n')
Hi world, nice to meet ya!
-> CLOSE
We can pass a name:
>>> connection = zc.ngi.testing.TextConnection()
>>> server = zc.monitor.Server(connection)
>>> connection.test_input('hello Jim\n')
Hi Jim, nice to meet ya!
-> CLOSE
The server comes with a few basic commands. Let's register
them so we can see what they do. We'll use the simplfied registration
interface:
>>> zc.monitor.register_basics()
The first is the help command. Giving help without input, gives a
list of available commands:
>>> connection = zc.ngi.testing.TextConnection()
>>> server = zc.monitor.Server(connection)
>>> connection.test_input('help\n')
Supported commands:
hello -- Say hello
help -- Get help about server commands
hi -- Say hello
interactive -- Turn on monitor's interactive mode
quit -- Quit the monitor
-> CLOSE
We can get detailed help by specifying a command name:
>>> connection = zc.ngi.testing.TextConnection()
>>> server = zc.monitor.Server(connection)
>>> connection.test_input('help help\n')
Help for help:
<BLANKLINE>
Get help about server commands
<BLANKLINE>
By default, a list of commands and summaries is printed. Provide
a command name to get detailed documentation for a command.
<BLANKLINE>
-> CLOSE
>>> connection = zc.ngi.testing.TextConnection()
>>> server = zc.monitor.Server(connection)
>>> connection.test_input('help hello\n')
Help for hello:
<BLANKLINE>
Say hello
<BLANKLINE>
Provide a name if you're not the world.
<BLANKLINE>
-> CLOSE
The ``interactive`` command switches the monitor into interactive mode. As
seen above, the monitor usually responds to a single command and then closes
the connection. In "interactive mode", the connection is not closed until
the ``quit`` command is used. This can be useful when accessing the monitor
via telnet for diagnostics.
>>> connection = zc.ngi.testing.TextConnection()
>>> server = zc.monitor.Server(connection)
>>> connection.test_input('interactive\n')
Interactive mode on. Use "quit" To exit.
>>> connection.test_input('help interactive\n')
Help for interactive:
<BLANKLINE>
Turn on monitor's interactive mode
<BLANKLINE>
Normally, the monitor releases the connection after a single command.
By entering the interactive mode, the monitor will not end the connection
until you enter the "quit" command.
<BLANKLINE>
In interactive mode, an empty line repeats the last command.
<BLANKLINE>
>>> connection.test_input('help quit\n')
Help for quit:
<BLANKLINE>
Quit the monitor
<BLANKLINE>
This is only really useful in interactive mode (see the "interactive"
command).
<BLANKLINE>
Notice that the result of the commands did not end with "-> CLOSE", which would
have indicated a closed connection.
Also notice that the interactive mode allows you to repeat commands.
>>> connection.test_input('hello\n')
Hi world, nice to meet ya!
>>> connection.test_input('\n')
Hi world, nice to meet ya!
>>> connection.test_input('hello Jim\n')
Hi Jim, nice to meet ya!
>>> connection.test_input('\n')
Hi Jim, nice to meet ya!
Now we will use ``quit`` to close the connection.
>>> connection.test_input('quit\n')
Goodbye.
-> CLOSE
Finally, it's worth noting that exceptions will generate a
traceback on the connection.
>>> connection = zc.ngi.testing.TextConnection()
>>> server = zc.monitor.Server(connection)
>>> connection.test_input('hello Jim 42\n') # doctest: +ELLIPSIS
Traceback (most recent call last):
...
TypeError: hello() takes at most 2 arguments (3 given)
<BLANKLINE>
-> CLOSE
.. Edge cases
Closing the connection:
>>> connection.test_close('test')
Command loops
-------------
Using the "MORE" mode, commands can signal that they want to claim all future
user input. We'll implement a silly example to demonstrate how it works.
Here's a command that implements a calculator.
>>> PROMPT = '.'
>>> def calc(connection, *args):
... if args and args[0] == 'quit':
... return zc.monitor.QUIT_MARKER
...
... if args:
... connection.write(str(eval(''.join(args))))
... connection.write('\n')
...
... connection.write(PROMPT)
... return zc.monitor.MORE_MARKER
If we register this command...
>>> zc.monitor.register(calc)
...we can invoke it and we get a prompt.
>>> connection = zc.ngi.testing.TextConnection()
>>> server = zc.monitor.Server(connection)
>>> connection.test_input('calc\n')
.
If we then give it more input we get the result plus another prompt.
>>> connection.test_input('2+2\n')
4
.
>>> connection.test_input('4*2\n')
8
.
Once we're done we can tell the calculator to let us go.
>>> connection.test_input('quit\n')
-> CLOSE
Start server
------------
>>> import time
>>> import zope.testing.loggingsupport, logging
>>> loghandler = zope.testing.loggingsupport.InstalledHandler(
... None, level=logging.INFO)
>>> zc.monitor.start(9644)
('', 9644)
>>> print loghandler
zc.ngi.async.server INFO
listening on ('', 9644)
>>> zc.monitor.last_listener.close()
>>> zc.monitor.last_listener = None
>>> time.sleep(0.1)
>>> loghandler.clear()
>>> zc.monitor.start(('127.0.0.1', 9644))
('127.0.0.1', 9644)
>>> print loghandler
zc.ngi.async.server INFO
listening on ('127.0.0.1', 9644)
>>> zc.monitor.last_listener.close()
>>> zc.monitor.last_listener = None
>>> time.sleep(0.1)
Bind to port 0:
>>> addr = zc.monitor.start(0)
>>> addr == zc.monitor.last_listener.address
True
>>> zc.monitor.last_listener.close()
>>> zc.monitor.last_listener = None
>>> time.sleep(0.1)
Trying to rebind to a port in use:
>>> loghandler.clear()
>>> zc.monitor.start(('127.0.0.1', 9644))
('127.0.0.1', 9644)
>>> zc.monitor.start(('127.0.0.1', 9644))
False
>>> print loghandler
zc.ngi.async.server INFO
listening on ('127.0.0.1', 9644)
zc.ngi.async.server WARNING
unable to listen on ('127.0.0.1', 9644)
root WARNING
unable to start zc.monitor server because the address ('127.0.0.1', 9644) is in use.
>>> zc.monitor.last_listener.close()
>>> zc.monitor.last_listener = None
>>> time.sleep(0.1)
>>> loghandler.uninstall()
PyPI 官网下载 | zc.monitor-0.4.0.post1.tar.gz
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2022-01-17
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