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A Python messaging library.

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README中文文档

About the Msgr Library

The Msgr library provide two class: MessageQueue and MessageBroker.

The MessageQueue class is an easy to use inerface to queues like Python queue, multiprocessing.Queue or [Redistr](https://www.github.com/copyrighthero/Redistr)’s redis Queue interface. It is defaulted to use multiprocessing.Queue as its queue.

The MessageBroker class is a class that manages one to four queues – job, resolve, reject and service queues respectively. The job queue is a must and is defaulted to a MessageQueue instance, the other three queues can be None. These queues can be changed when instantiating.

The MessageQueue is a thin wrapper around queue objects that has put and get methods, and the MessageBroker is the manager class for dispatching and receiving messages.

They can be used in multiprocessing environments for message passing between processes.

How to Use Msgr Library

After installation using pip install Msgr, simply import and start coding :-)

from msgr import MessageQueue, MessageBroker
from redis import Redis
from redistr import Queue

# create message queues
mqq = MessageQueue() # default, use `multiprocessing.Queue`
redis_queue = Queue(Redis(), 'queue_key') # create redistr Queue
redis_mqq = MessageQueue(redis_queue) # use redistr Queue instead

# most queue operations: put, get.
mqq.put({'test': 'case'})
mqq.get() # {'test': 'case'}
# `MessageQueue` exposes queue's properties
redis_mqq.length # 0, redistr queue's length property
# `MessageQueue` has msg property for convenience
redis_mqq.msg = 'test' # send a message, like `put('test')`
redis_mqq.msg = 'case'
redis_mqq.msg # 'test', get a message like `get()`
redis_mqq.msg # 'case'
# `MessageQueue` has __call__ method for put/get message
mqq('testcase') # send a message to queue
mqq() # 'testcase' # get a message from queue

# The MessageQueue is enough in most situations,
#   but if you want, the MessageBroker is here to help

# create message broker instance
#   default to use MessageQueue as its job queue, no resolve/reject/service queues
mb = MessageBroker()
#   change the job queue, resolve queue, reject queue or service queue
mb = MessageBroker(job = mqq, res = MessageQueue(), rej = redis_queue, ser = redis_mqq)

# dispath/acquire a job message
mb.dispatch('job message')
mb.acquire() # 'job message' received

# resolve a result, settle a resolved message
mb.resolve('job done')
mb.settle() # 'job done' received

# reject a result, handle a rejected message
mb.reject('job failed')
mb.handle() # 'job failed' received

# get or put a pair of resolve, reject messages
#   .inspect is non-blocking by default, can be changed to blocking
mb.conclude('resolve msg', 'reject msg')
mb.inspect() # ('resolve msg', 'reject msg') received.
mb.inspect() # (None, None)
mb.reject('failed')
mb.inspect() # (None, 'failed')

# request a service, process a service
mb.request('shutdown')
mb.process() # 'shutdown' received

# helper properties are provided
#   job queue properties, blocking
mb.msg = 'test'
mb.msg # 'test' received
mb.job = 'test'
mb.job # 'test' received
#   resolve queue property, blocking
mb.res = 'resolved'
mb.res # 'resolved' received
#   reject queue property, blocking
mb.rej = 'failed'
mb.rej # 'failed' received
#   service queue property, blocking
mb.ser = 'reboot'
mb.ser # 'reboot' received
#   inspect method property, non-blocking
mb.ram # (None, None) received

Msgr Class API References

MessageQueue Class

The thin wrapper for queues, exposes put, set, send for sending messages and get, recv for getting messages. It also exposes a __call__ method and a msg property for sending/receiving messages. It also exposes all the queue properties for the user’s conveniences.

Signature: MessageQueue(queue = None, messages = None, *args)

  1. queue parameter: it takes in any instances that has put and get methods for sending and receiving messages, so it works with queue, multiprocessing.Queue and redistr.Queue objects. When nothing is passed in, it will use multiprocessing.Queue by default.
  2. messages parameter: a iterable object should be passed in, all items in this iterable will be sent to the queue when instantiating.
  3. *args parameter: any stray parameters will be considered as a message and will be sent to the queue.
  • put(message), send(..), set(..) method: send a message to the queue.
  • get(block = True, timeout = 0), recv(..) method: get a message from queue, blocking operation, can pass in block = False to prevent blocking or timeout = [second] for changing block timeout.
  • __call__(message = None): if calling the instance directly without parameter, it will receive an message blocking; if the instance is called with one parameter, the parameter will be send to the queue.
  • msg property: assignment to this property will send a message, simply accessing the property will get a message blocking.

MessageBroker Class

The manager class for up to four queues of different usage. It takes four optional parameters: job, res, rej and ser corresponding to job queue, resolve queue, reject queue and service queue. By default if job queue is not passed in it will use MessageQueue as the job queue, which uses multiprocessing.Queue as its underlying queue.

The class also exposes different methods and properties for sending and receiving from different queues.

Signature: MessageBroker(job = None, res = None, rej = None, ser = None)

1.2.3.4 job, res, rej, ser parameters: any queue instances, they can be the same but why do you want to do that?

  • __call__(message = None) method: send/receive a job message to/from the job queue.
  • dispatch(message), set(..), put(..), send(..) method: send a job message.
  • acquire(block = True, timeout = 0), get(..), recv(..) method: get a job message blocking.
  • resolve(message) method: send a resolve (success) message to resolve queue.
  • settle(block = True, timeout = 0) method: get a resolved message from resolve queue.
  • reject(message) method: send a reject (fail) message to reject queue.
  • handle(block = True, timeout = 0) method: get a rejected message from reject queue.
  • concude(resolve = None, reject = None) method: send a pair of result messages as resolved and rejected msgs.
  • inspect(block = False, timeout = 0) method: get a pair of result messages non-blocking.
  • request(message) method: send a service request message.
  • process(block = True, timeout = 0) method: get a service request message blocking.
  • msg, job property: send/get a job message, blocking.
  • res property: send/get a resolve message, blocking.
  • rej property: send/get a reject message, blocking.
  • ser property: send/get a service request message, blocking.
  • ram property: get a pair of results from resolve queue and reject queue, non-blocking.

Licenses

This project is licensed under two permissive licenses, please chose one or both of the licenses to your like. Although not necessary, bug reports or feature improvements, attributes to the author(s), information on how this program is used are welcome and appreciated :-) Happy coding

[BSD-2-Clause License]

Copyright 2018 Hansheng Zhao

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

  1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
  2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS “AS IS” AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

[MIT License]

Copyright 2018 Hansheng Zhao

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

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