Introduction to naz¶

naz is an async SMPP client. It’s name is derived from Kenyan hip hop artiste, Nazizi.

SMPP is a protocol designed for the transfer of short message data between External Short Messaging Entities(ESMEs), Routing Entities(REs) and Short Message Service Center(SMSC). - Wikipedia

naz currently only supports SMPP version 3.4.

naz has no third-party dependencies and it requires python version 3.7+

naz is in active development and it’s API may change in backward incompatible ways.

Table of Contents

1 Installation
2 Usage
2.1 As a library
2.2 As a cli app
3 Features
3.1 async everywhere
3.2 monitoring and observability
3.2.1 logging
3.2.2 hooks
3.2.3 integration with bug trackers
3.3 Rate limiting
3.4 Throttle handling
3.5 Broker
4 Benchmarks

2.1 As a library ¶

import asyncio
import naz

loop = asyncio.get_event_loop()
broker = naz.broker.SimpleBroker(maxsize=1000)
cli = naz.Client(
    smsc_host="127.0.0.1",
    smsc_port=2775,
    system_id="smppclient1",
    password="password",
    broker=broker,
)

# queue messages to send
for i in range(0, 4):
    print("submit_sm round:", i)

    msg = naz.protocol.SubmitSM(
            short_message="Hello World-{0}".format(str(i)),
            log_id="myid12345",
            source_addr="254722111111",
            destination_addr="254722999999",
        )
    loop.run_until_complete(
       cli.send_message(msg)
)

try:
    # 1. connect to the SMSC host
    # 2. bind to the SMSC host
    # 3. send any queued messages to SMSC
    # 4. read any data from SMSC
    # 5. continually check the state of the SMSC
    tasks = asyncio.gather(
        cli.connect(),
        cli.tranceiver_bind(),
        cli.dequeue_messages(),
        cli.receive_data(),
        cli.enquire_link(),
    )
    loop.run_until_complete(tasks)
except Exception as e:
    print("exception occured. error={0}".format(str(e)))
finally:
    loop.run_until_complete(cli.unbind())
    loop.stop()

NB:

1. For more information about all the parameters that naz.Client can take, consult the docs
1. More examples can be found here
1. if you need an SMSC server/gateway to test with, you can use the docker-compose file in the naz repo to bring up an SMSC simulator. That docker-compose file also has a redis and rabbitMQ container if you would like to use those as your naz.broker.BaseBroker.

2.2 As a cli app ¶

naz also ships with a commandline interface app called naz-cli (it is also installed by default when you pip install naz).

create a python config file, eg; /tmp/my_app.py

import naz
from myfile import ExampleBroker

client = naz.Client(
    smsc_host="127.0.0.1",
    smsc_port=2775,
    system_id="smppclient1",
    password="password",
    broker=ExampleBroker()
)

and a python file, myfile.py (in the current working directory) with the contents:

import asyncio
import naz
class ExampleBroker(naz.broker.BaseBroker):
    def __init__(self):
        loop = asyncio.get_event_loop()
        self.queue = asyncio.Queue(maxsize=1000, loop=loop)
    async def enqueue(self, message):
        self.queue.put_nowait(message)
    async def dequeue(self):
        return await self.queue.get()

then run: naz-cli --client tmp.my_app.client

NB:

1. The naz config file(ie, the dotted path we pass in to naz-cli --client) is any python file that has a naz.Client instance declared in it.
1. More examples can be found; examples As an example, start the SMSC simulator(docker-compose up) then in another terminal run, naz-cli --client examples.example_config.client

3.1 async everywhere ¶

SMPP is an async protocol; the client can send a request and only get a response from SMSC/server 20mins later out of band.

It thus makes sense to write your SMPP client in an async manner. We leverage python3’s async/await to do so.

import naz
import asyncio
loop = asyncio.get_event_loop()
broker = naz.broker.SimpleBroker(maxsize=1000)
cli = naz.Client(
    smsc_host="127.0.0.1",
    smsc_port=2775,
    system_id="smppclient1",
    password="password",
    broker=broker,
)

3.2 monitoring and observability ¶

3.2.1 logging ¶

In naz you have the ability to annotate all the log events that naz will generate with anything you want.

So, for example if you wanted to annotate all log-events with a release version and your app’s running environment.

import naz
logger = naz.log.SimpleLogger(
            "naz.client",
            log_metadata={ "environment": "production", "release": "v5.6.8"}
        )
cli = naz.Client(
    ...
    logger=logger,
)

and then these will show up in all log events.

by default, naz annotates all log events with smsc_host, system_id and client_id

naz also gives you the ability to supply your own logger. All you have to do is pass in a python logging.Logger

For example if you wanted naz to use key=value style of logging, then just create a logger that does just that:

import naz

class KVlogger(logging.Logger):
    """
    A simple implementation of a key=value
    log renderer.
    """

    def __init__(self, name, level=logging.INFO):
        super(KVlogger, self).__init__(name, level)
        handler = logging.StreamHandler()
        formatter = logging.Formatter("%(message)s")
        handler.setFormatter(formatter)
        self.addHandler(handler)
        self.setLevel("DEBUG")

    def log(self, level, msg, *args, **kwargs):
        new_msg = self._process_msg(msg)
        return super(KVlogger, self).log(level, new_msg, *args, **kwargs)

    def _process_msg(self, message):
        # implementation of key=value log renderer
        new_msg = ", ".join("{0}={1}".format(k, v) for k, v in message.items())
        return new_msg


kvLog = KVlogger()
cli = naz.Client(
    ...
    logger=kvLog,
)

3.2.2 hooks ¶

A hook is a class with two methods to_smsc and from_smsc, ie it implements naz’s naz.hooks.BaseHook interface
naz will call the to_smsc method just before sending data to SMSC and also call the from_smsc method just after getting data from SMSC.
The default hook that naz uses is naz.hooks.SimpleHook which just logs the request and response.
If you wanted, for example to keep metrics of all requests and responses to SMSC in your prometheus setup;

import naz
from prometheus_client import Counter

class MyPrometheusHook(naz.hooks.BaseHook):
    async def to_smsc(self, smpp_command, log_id, hook_metadata, pdu):
        c = Counter('my_requests', 'Description of counter')
        c.inc() # Increment by 1
    async def from_smsc(self,
                    smpp_command,
                    log_id,
                    hook_metadata,
                    status,
                    pdu):
        c = Counter('my_responses', 'Description of counter')
        c.inc() # Increment by 1

myHook = MyPrometheusHook()
cli = naz.Client(
    ...
    hook=myHook,
)

another example is if you want to update a database record whenever you get a delivery notification event;

import sqlite3
import naz

class SetMessageStateHook(naz.hooks.BaseHook):
    async def to_smsc(self, smpp_command, log_id, hook_metadata, pdu):
        pass
    async def from_smsc(self,
                    smpp_command,
                    log_id,
                    hook_metadata,
                    status,
                    pdu):
        if smpp_command == naz.SmppCommand.DELIVER_SM:
            conn = sqlite3.connect('mySmsDB.db')
            c = conn.cursor()
            t = (log_id,)
            # watch out for SQL injections!!
            c.execute("UPDATE SmsTable SET State='delivered' WHERE CorrelatinID=?", t)
            conn.commit()
            conn.close()

stateHook = SetMessageStateHook()
cli = naz.Client(
    ...
    hook=stateHook,
)

3.2.3 integration with bug trackers ¶

If you want to integrate naz with your bug/issue tracker of choice, all you have to do is use their logging integrator.

As an example, to integrate naz with sentry, all you have to do is import and init the sentry sdk. A good place to do that would be in the naz config file, ie;

/tmp/my_config.py

import naz
from myfile import ExampleBroker

import sentry_sdk # import sentry SDK
sentry_sdk.init("https://<YOUR_SENTRY_PUBLIC_KEY>@sentry.io/<YOUR_SENTRY_PROJECT_ID>")

my_naz_client = naz.Client(
    smsc_host="127.0.0.1",
    smsc_port=2775,
    system_id="smppclient1",
    password="password",
    broker=ExampleBroker()
)

then run the naz-cli as usual:
naz-cli --client tmp.my_config.my_naz_client
And just like that you are good to go. This is what errors from naz will look like on sentry(sans the emojis, ofcourse):

3.3 Rate limiting ¶

Sometimes you want to control the rate at which the client sends requests to an SMSC/server. naz lets you do this, by allowing you to specify a custom rate limiter.

By default, naz uses a simple token bucket rate limiting algorithm implemented in naz.ratelimiter.SimpleRateLimiter

You can customize naz’s ratelimiter or even write your own ratelimiter (if you decide to write your own, you just have to satisfy the naz.ratelimiter.BaseRateLimiter interface)

To customize the default ratelimiter, for example to send at a rate of 35 requests per second.

import naz

myLimiter = naz.ratelimiter.SimpleRateLimiter(send_rate=35)
cli = naz.Client(
    ...
    rate_limiter=myLimiter,
)

3.4 Throttle handling ¶

Sometimes, when a client sends requests to an SMSC/server, the SMSC may reply with an ESME_RTHROTTLED status.

This can happen, say if the client has surpassed the rate at which it is supposed to send requests at, or the SMSC is under load or for whatever reason ¯_(ツ)_/¯

The way naz handles throtlling is via Throttle handlers. A throttle handler is a class that implements the naz.throttle.BaseThrottleHandler interface

By default naz uses naz.throttle.SimpleThrottleHandler to handle throttling. As an example if you want to deny outgoing requests if the percentage of throttles is above 1.2% over a period of 180 seconds and the total number of responses from SMSC is greater than 45, then;

from naz.throttle import SimpleThrottleHandler
throttler = SimpleThrottleHandler(sampling_period=180,
                                sample_size=45,
                                deny_request_at=1.2)
cli = naz.Client(
    ...
    throttle_handler=throttler,
)

3.5 Broker ¶

How does your application and naz talk with each other?

It’s via a broker interface. Your application queues messages to a broker, naz consumes from that broker and then naz sends those messages to SMSC/server.

You can implement the broker mechanism any way you like, so long as it satisfies the naz.broker.BaseBroker interface

Your application should call that class’s enqueue method to enqueue messages.

naz ships with a simple broker implementation called naz.broker.SimpleBroker

NB: naz.broker.SimpleBroker should only be used for demo/test purposes.

An example of using that broker;

import asyncio
import naz

loop = asyncio.get_event_loop()
my_broker = naz.broker.SimpleBroker(maxsize=1000) # can hold upto 1000 items
cli = naz.Client(
    ...
    broker=my_broker,
)

try:
    # 1. connect to the SMSC host
    # 2. bind to the SMSC host
    # 3. send any queued messages to SMSC
    # 4. read any data from SMSC
    # 5. continually check the state of the SMSC
    tasks = asyncio.gather(
        cli.connect(),
        cli.tranceiver_bind(),
        cli.dequeue_messages(),
        cli.receive_data(),
        cli.enquire_link(),
    )
    loop.run_until_complete(tasks)
except Exception as e:
    print("exception occured. error={0}".format(str(e)))
finally:
    loop.run_until_complete(cli.unbind())
    loop.stop()
then in your application, queue items to the queue;

# queue messages to send
for i in range(0, 4):
    msg = naz.protocol.SubmitSM(
            short_message="Hello World-{0}".format(str(i)),
            log_id="myid12345",
            source_addr="254722111111",
            destination_addr="254722999999",
        )
    loop.run_until_complete(
       cli.send_message(msg)
    )

then in your application, queue items to the queue;

# queue messages to send
for i in range(0, 4):
    msg = naz.protocol.SubmitSM(
            short_message="Hello World-{0}".format(str(i)),
            log_id="myid12345",
            source_addr="254722111111",
            destination_addr="254722999999",
        )
    loop.run_until_complete(
      cli.send_message(msg)
)

4 Benchmarks ¶

Benchmarks can be found; benchmarks