osbrain.agent — osBrain agent logic

Core agent classes.

class osbrain.agent.Agent(name='', host=None, serializer=None, transport=None, attributes=None)

Bases: object

A base agent class which is to be served by an AgentProcess.

An AgentProcess runs a Pyro multiplexed server and serves one Agent object.

Parameters:
name : str, default is None

Name of the Agent.

host : str, default is None

Host address where the agent will bind to. When not set, '127.0.0.1' (localhost) is used.

transport : str, AgentAddressTransport, default is None

Transport protocol.

attributes : dict, default is None

A dictionary that defines initial attributes for the agent.

Attributes:
name : str

Name of the agent.

_host : str

Host address where the agent is binding to.

_uuid : bytes

Globally unique identifier for the agent.

_running : bool

Set to True if the agent is running (executing the main loop).

_serializer : str

Default agent serialization format.

_transport : str, AgentAddressTransport, default is None

Default agent transport protocol.

_socket : dict

A dictionary in which the key is the address or the alias and the value is the actual socket.

_address : dict

A dictionary in which the key is the address or the alias and the value is the actual address.

_handler : dict

A dictionary in which the key is the socket and the values are the handlers for each socket.

_context : zmq.Context

ZMQ context to create ZMQ socket objects.

_poller : zmq.Poller

ZMQ poller to wait for incoming data from sockets.

_poll_timeout : int

Polling timeout, in milliseconds. After this timeout, if no message is received, the agent executes de idle() method before going back to polling.

_keep_alive : bool

When set to True, the agent will continue executing the main loop.

_async_req_uuid : dict

Stores the UUIDs of the asynchronous request sockets (used in communication channels).

_async_req_handler : dict

Stores the handler for every asynchronous request sockets (used in communication channels).

_die_now : bool

During shutdown, this attribute is set for the agent to die.

_DEBUG : bool

Whether to print debug level messages.

_pending_requests : dict

Stores pending (waiting for reply) asynchronous requests. The asynchronous request UUID is used as key and its handler as the value.

_timer : dict

Stores all the current active timers, using their aliases as keys.

Methods

addr(alias) Return the address of a socket given by its alias.
after(delay, method, *args[, alias]) Execute an action after a delay.
before_loop() This user-defined method is to be executed right before the main loop.
bind(kind[, alias, handler, addr, …]) Bind to an agent address.
close(alias[, linger]) Close a socket given its alias and clear its entry from the Agent.socket dictionary.
close_all([linger]) Close all non-internal zmq sockets.
connect(server[, alias, handler]) Connect to a server agent address.
each(period, method, *args[, alias]) Execute a repeated action with a defined period.
execute_as_function(function, *args, **kwargs) Execute a function passed as parameter.
execute_as_method(function, *args, **kwargs) Execute a function as a method, without adding it to the set of agent methods.
get_attr(name) Return the specified attribute of the agent.
has_socket(alias) Return whether the agent has the passed socket internally stored.
idle() This function is to be executed when the agent is idle.
is_running() Returns a boolean indicating whether the agent is running or not.
kill() Force shutdown of the agent.
list_timers() Return a list with all timer aliases currently running.
log_debug(message[, logger]) Log a debug message.
log_error(message[, logger]) Log an error message.
log_info(message[, logger]) Log an info message.
log_warning(message[, logger]) Log a warning message.
on_init() This user-defined method is to be executed after initialization.
ping() A test method to check the readiness of the agent.
raise_exception() Raise an exception (for testing purposes).
recv(address) Receive a message from the specified address.
run() Start the main loop.
safe_call(method, *args, **kwargs) A safe call to a method.
send(address, message[, topic, handler, …]) Send a message through the specified address.
send_recv(address, message) This method is only used in REQREP communication patterns.
set_attr(**kwargs) Set object attributes.
set_logger(logger[, alias]) Connect the agent to a logger and start logging messages to it.
set_method(*args, **kwargs) Set object methods.
shutdown() Cleanly stop and shut down the agent assuming the agent is running.
stop() Stop the agent.
stop_all_timers() Stop all currently running timers.
stop_timer(alias) Stop a currently running timer.
subscribe(alias, handler, str], Any]) Subscribe a SUB/SYNC_SUB socket given by its alias to the given topics, and leave the handlers prepared internally.
unsubscribe(alias, topic, str]) Unsubscribe a SUB/SYNC_SUB socket given by its alias from a given specific topic, and delete its entry from the handlers dictionary.
addr(alias)

Return the address of a socket given by its alias.

Parameters:
alias : str

Alias of the socket whose address is to be retrieved.

Returns:
AgentAddress

Address of the agent socket associated with the alias.

after(delay, method, *args, alias=None, **kwargs)

Execute an action after a delay.

Parameters:
delay : float

Execute the action after delay seconds.

method

Method (action) to be executed by the agent.

alias : str, default is None

An alias for the generated timer.

*args : tuple

Parameters to pass for the method execution.

**kwargs : dict

Named parameters to pass for the method execution.

Returns:
str

The timer alias or identifier.

before_loop()

This user-defined method is to be executed right before the main loop.

bind(kind, alias=None, handler=None, addr=None, transport=None, serializer=None)

Bind to an agent address.

Parameters:
kind : str, AgentAddressKind

The agent address kind: PUB, REQ…

alias : str, default is None

Optional alias for the socket.

handler, default is None

If the socket receives input messages, the handler/s is/are to be set with this parameter.

addr : str, default is None

The address to bind to.

transport : str, AgentAddressTransport, default is None

Transport protocol.

Returns:
AgentAddress

The address where the agent binded to.

close(alias, linger=None)

Close a socket given its alias and clear its entry from the Agent.socket dictionary.

close_all(linger=None)

Close all non-internal zmq sockets.

connect(server, alias=None, handler=None)

Connect to a server agent address.

Parameters:
server : AgentAddress

Agent address to connect to.

alias : str, default is None

Optional alias for the new address.

handler, default is None

If the new socket receives input messages, the handler/s is/are to be set with this parameter.

each(period, method, *args, alias=None, **kwargs)

Execute a repeated action with a defined period.

Parameters:
period : float

Repeat the action execution with a delay of period seconds between executions.

method

Method (action) to be executed by the agent.

alias : str, default is None

An alias for the generated timer.

*args : tuple

Parameters to pass for the method execution.

**kwargs : dict

Named parameters to pass for the method execution.

Returns:
str

The timer alias or identifier.

execute_as_function(function, *args, **kwargs)

Execute a function passed as parameter.

execute_as_method(function, *args, **kwargs)

Execute a function as a method, without adding it to the set of agent methods.

get_attr(name: str)

Return the specified attribute of the agent.

Parameters:
name

Name of the attribute to be retrieved.

has_socket(alias)

Return whether the agent has the passed socket internally stored.

idle()

This function is to be executed when the agent is idle.

After a timeout occurs when the agent’s poller receives no data in any of its sockets, the agent may execute this function.

is_running()

Returns a boolean indicating whether the agent is running or not.

kill()

Force shutdown of the agent.

If the agent is running the ZMQ context is terminated to allow the main thread to quit and do the tear down.

list_timers()

Return a list with all timer aliases currently running.

Returns:
list (str)

A list with all the timer aliases currently running.

log_debug(message, logger='_logger')

Log a debug message.

Parameters:
message : str

Message to log.

logger : str

Alias of the logger.

log_error(message, logger='_logger')

Log an error message.

Parameters:
message : str

Message to log.

logger : str

Alias of the logger.

log_info(message, logger='_logger')

Log an info message.

Parameters:
message : str

Message to log.

logger : str

Alias of the logger.

log_warning(message, logger='_logger')

Log a warning message.

Parameters:
message : str

Message to log.

logger : str

Alias of the logger.

on_init()

This user-defined method is to be executed after initialization.

ping()

A test method to check the readiness of the agent. Used for testing purposes, where timing is very important. Do not remove.

raise_exception()

Raise an exception (for testing purposes).

recv(address)

Receive a message from the specified address.

This method is only used in REQREP communication patterns.

Parameters:
address :
Returns:
anything

The content received in the address.

run()

Start the main loop.

safe_call(method, *args, **kwargs)

A safe call to a method.

A safe call is simply sent to be executed by the main thread.

Parameters:
method : str

Method name to be executed by the main thread.

*args : arguments

Method arguments.

*kwargs : keyword arguments

Method keyword arguments.

send(address, message, topic=None, handler=None, wait=None, on_error=None)

Send a message through the specified address.

Note that replies in a REQREP pattern do not use this function in order to be sent.

Parameters:
address : AgentAddress or AgentChannel

The address to send the message through.

message

The message to be sent.

topic : str

The topic, in case it is relevant (i.e.: for PUB sockets).

handler : function, method or string

Code that will be executed on input messages if relevant (i.e.: for asynchronous requests in channels).

wait : float

For channel requests, wait at most this number of seconds for a response from the server.

on_error : function, method or string

Code to be executed if wait is passed and the response is not received.

send_recv(address, message)

This method is only used in REQREP communication patterns.

set_attr(**kwargs)

Set object attributes.

Parameters:
kwargs : [name, value]

Keyword arguments will be used to set the object attributes.

set_logger(logger, alias='_logger')

Connect the agent to a logger and start logging messages to it.

set_method(*args, **kwargs)

Set object methods.

Parameters:
args : [function]

New methods will be created for each function, taking the same name as the original function.

kwargs : [name, function]

New methods will be created for each function, taking the name specified by the parameter.

Returns:
str

Name of the registered method in the agent.

shutdown()

Cleanly stop and shut down the agent assuming the agent is running.

Will let the main thread do the tear down.

stop()

Stop the agent. Agent will stop running.

stop_all_timers()

Stop all currently running timers.

stop_timer(alias)

Stop a currently running timer.

Parameters:
alias : str

The alias or identifier of the timer.

subscribe(alias: str, handler: Dict[Union[bytes, str], Any]) → None

Subscribe a SUB/SYNC_SUB socket given by its alias to the given topics, and leave the handlers prepared internally.

Parameters:
alias

Alias of the new subscriber socket.

handler

A dictionary in which the keys represent the different topics and the values the actual handlers. If, instead of a dictionary, a single handler is given, it will be used to subscribe the agent to any topic.

unsubscribe(alias: str, topic: Union[bytes, str]) → None

Unsubscribe a SUB/SYNC_SUB socket given by its alias from a given specific topic, and delete its entry from the handlers dictionary.

If instead of a single topic, a tuple or a list of topics is passed, the agent will unsubscribe from all the supplied topics.

class osbrain.agent.AgentProcess(name='', nsaddr=None, addr=None, serializer=None, transport=None, base=<class 'osbrain.agent.Agent'>, attributes=None)

Bases: multiprocessing.context.Process

Agent class. Instances of an Agent are system processes which can be run independently.

Attributes:
authkey
daemon

Return whether process is a daemon

exitcode

Return exit code of process or None if it has yet to stop

ident

Return identifier (PID) of process or None if it has yet to start

name
pid

Return identifier (PID) of process or None if it has yet to start

sentinel

Return a file descriptor (Unix) or handle (Windows) suitable for waiting for process termination.

Methods

is_alive() Return whether process is alive
join([timeout]) Wait until child process terminates
kill() Force kill the agent process.
run() Begin execution of the agent process and start the main loop.
start() Start the system process.
terminate() Terminate process; sends SIGTERM signal or uses TerminateProcess()
kill()

Force kill the agent process.

run()

Begin execution of the agent process and start the main loop.

start()

Start the system process.

Raises:
RuntimeError

If an error occurred when initializing the daemon.

osbrain.agent.compose_message(message: bytes, topic: bytes, serializer: osbrain.address.AgentAddressSerializer) → bytes

Compose a message and leave it ready to be sent through a socket.

This is used in PUB-SUB patterns to combine the topic and the message in a single bytes buffer.

Parameters:
message

Message to be composed.

topic

Topic to combine the message with.

serializer

Serialization for the message part.

Returns:
The bytes representation of the final message to be sent.
osbrain.agent.deserialize_message(message, serializer)

Check if a message needs to be deserialized and do it if that is the case.

Parameters:
message : bytes, memoryview

The serialized message.

serializer : AgentAddressSerializer

The type of (de)serializer that should be used.

Returns:
anything

The deserialized message, or the same message in case no deserialization is needed.

osbrain.agent.execute_code_after_yield(generator)

Some responses are dispatched with yield (generator handler). In those cases we still want to execute the remaining code in the generator, and also make sure it does not yield any more.

Raises:
ValueError

If the generator yielded once more, which is unexpected.

osbrain.agent.run_agent(name='', nsaddr=None, addr=None, base=<class 'osbrain.agent.Agent'>, serializer=None, transport=None, safe=None, attributes=None)

Ease the agent creation process.

This function will create a new agent, start the process and then run its main loop through a proxy.

Parameters:
name : str, default is ‘’

Agent name or alias.

nsaddr : SocketAddress, default is None

Name server address.

addr : SocketAddress, default is None

New agent address, if it is to be fixed.

transport : str, AgentAddressTransport, default is None

Transport protocol.

safe : bool, default is None

Use safe calls by default from the Proxy.

attributes : dict, default is None

A dictionary that defines initial attributes for the agent.

Returns:
proxy

A proxy to the new agent.

osbrain.agent.serialize_message(message, serializer)

Check if a message needs to be serialized and do it if that is the case.

Parameters:
message : anything

The message to serialize.

serializer : AgentAddressSerializer

The type of serializer that should be used.

Returns:
bytes

The serialized message, or the same message in case no serialization is needed.