Michio JP

Michio JP

1566883397

Getting Started With RabbitMQ: Python

In this article, I am going to explain RabbitMQ.

RabbitMQ is a message broker. It accepts and forwards messages. A message broker acts as an intermediary platform when it comes to processing communication between two applications

Let’s first discuss the scenario where RabbitMQ could be useful:

Suppose you own a restaurant. Now imagine the situation where users are placing the order simultaneously and the backend servers are not processing the orders as fast as they should, or some backend error has occurred or hardware is malfunctioned. Since all the requests were directly handled by the server, these requests will not be processed.

Now let’s see how RabbitMQ can resolve this:

We can place a service in between the two services, i.e front-end and backend. That service is Rabbit. It will consume all messages from the front-end and will only release when the backend is ready to process it.

Message brokers do many things such as:

  • Decouple message publisher and consumer: A message queue provides an ***asynchronous communications protocol. ***You have the option to send a message from one service to another without having to know if another service is able to handle it immediately or not. Messages can wait until the responsible service is ready. A service publishing a message does not need to know anything about the inner workings of the services that will process that message. This way of handling messages **decouple **the producer from the consumer.
  • Store the messages
  • Routing of messages
  • Monitoring and management of messages

Let’s understand a few terms first:

  • **Producer: **A program that sends messages.
  • **Consumer: **A program that receives messages.
  • **Channel: **A channel is a virtual connection inside a connection. When you are publishing or consuming messages from a queue — it’s all done over a channel.
  • **Connection: **A connection is a TCP connection between your application and the RabbitMQ broker.
  • Routing Key: Routing keybinding with the queue are ruled that allow the exchange to put messages into the queue.
  • **Exchange: **The exchange receives messages from the producer and from the other side it pushes them to the queues. The exchange must know exactly what to do with the messages it receives. Should it be appended to a particular queue? Should it be appended to many queues? Or should it get discarded? The rules for determining that are defined by the exchange type.

There are mainly four type of exchanges available:

  1. Direct: Sends a message to the queue whose binding key matches.
  2. Topic: Sends the message on basis of the pattern.
  3. Headers: A headers exchange is an exchange which routes messages to queues based on message header values instead of routing key.
  4. Fanout: Sends a message to all the queues.

The RabbitMQ server is written in the Erlang programming language and is built on the Open Telecom Platform(OTP) framework for clustering and failover.

The producer creates a message and sends (publishes) into the message broker (RabbitMQ). A message must have two parts: a payload and a label(routing key). The payload is data and it can be anything from a simple JSON to MPEG-4 file.

Each queue is bound to a routing key or a pattern of routing keys. This routing keybinding with the queue is ruled that allow the exchange to put messages into the queue. The label describes the payload and how RabbitMQ will determine who should get a copy of the message.

The communication between publisher and RabbitMQ is one directional and fire and forget. The consumer, on the other hand, attaches to the broker and subscribes to a queue to get the message.

RabbitMQ speaks **AMQP 0.9.1 Advanced Message Queuing Protocol, **which is an open, general-purpose protocol for messaging.

In null-set, AMQP defines:

  • Where to send messages (Routing)
  • How to get there (Delivery)
  • What goes in must come out (Fidelity)

RabbitMQ provides persistence, delivery acknowledgments, publisher confirms and high availability.

Let’s understand using an example how RabbitMQ works:

Pika is a python client for RabbitMQ in python.

Pika is a pure-Python implementation of the AMQP 0-9-1 protocol that tries to stay fairly independent of the underlying network support library. To install pika run:

pip install pika

publish.py

import pika

#Create a new instance of the Connection object
connection = pika.BlockingConnection(pika.ConnectionParameters(host='localhost'))

#Create a new channel with the next available channel number or pass in a channel number to use
channel = connection.channel()

#Declare queue, create if needed. This method creates or checks a queue. When creating a new queue the client can specify various properties that control the durability of the queue and its contents, and the level of sharing for the queue.
channel.queue_declare(queue='hello')

channel.basic_publish(exchange='', routing_key='hello', body='Hello World!')    

print("[x] Sent 'Hello World!'")

connection.close()

subscribe.py

import pika

connection = pika.BlockingConnection(pika.ConnectionParameters(host='localhost'))

channel = connection.channel()

channel.queue_declare(queue='hello')

def callback(ch, method, properties, body):
print(" [x] Received %r" % body) 

channel.basic_consume(callback, queue='hello', no_ack=True)

print(' [*] Waiting for messages. To exit press CTRL+C')

channel.start_consuming()

Now start the Consumer, it will run continuously waiting for deliveries:

python publish.py

=> [*] Waiting for messages. To exit press CTRL+C

=> [x] Received ‘Hello World!’

Now start the producer. The producer program will stop after every run:

python subscribe.py

=> [x] Sent ‘Hello World!’

Thanks for reading!

#python

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Getting Started With RabbitMQ: Python
Ray  Patel

Ray Patel

1619518440

top 30 Python Tips and Tricks for Beginners

Welcome to my Blog , In this article, you are going to learn the top 10 python tips and tricks.

1) swap two numbers.

2) Reversing a string in Python.

3) Create a single string from all the elements in list.

4) Chaining Of Comparison Operators.

5) Print The File Path Of Imported Modules.

6) Return Multiple Values From Functions.

7) Find The Most Frequent Value In A List.

8) Check The Memory Usage Of An Object.

#python #python hacks tricks #python learning tips #python programming tricks #python tips #python tips and tricks #python tips and tricks advanced #python tips and tricks for beginners #python tips tricks and techniques #python tutorial #tips and tricks in python #tips to learn python #top 30 python tips and tricks for beginners

Ray  Patel

Ray Patel

1619510796

Lambda, Map, Filter functions in python

Welcome to my Blog, In this article, we will learn python lambda function, Map function, and filter function.

Lambda function in python: Lambda is a one line anonymous function and lambda takes any number of arguments but can only have one expression and python lambda syntax is

Syntax: x = lambda arguments : expression

Now i will show you some python lambda function examples:

#python #anonymous function python #filter function in python #lambda #lambda python 3 #map python #python filter #python filter lambda #python lambda #python lambda examples #python map

Art  Lind

Art Lind

1602968400

Python Tricks Every Developer Should Know

Python is awesome, it’s one of the easiest languages with simple and intuitive syntax but wait, have you ever thought that there might ways to write your python code simpler?

In this tutorial, you’re going to learn a variety of Python tricks that you can use to write your Python code in a more readable and efficient way like a pro.

Let’s get started

Swapping value in Python

Instead of creating a temporary variable to hold the value of the one while swapping, you can do this instead

>>> FirstName = "kalebu"
>>> LastName = "Jordan"
>>> FirstName, LastName = LastName, FirstName 
>>> print(FirstName, LastName)
('Jordan', 'kalebu')

#python #python-programming #python3 #python-tutorials #learn-python #python-tips #python-skills #python-development

Art  Lind

Art Lind

1602666000

How to Remove all Duplicate Files on your Drive via Python

Today you’re going to learn how to use Python programming in a way that can ultimately save a lot of space on your drive by removing all the duplicates.

Intro

In many situations you may find yourself having duplicates files on your disk and but when it comes to tracking and checking them manually it can tedious.

Heres a solution

Instead of tracking throughout your disk to see if there is a duplicate, you can automate the process using coding, by writing a program to recursively track through the disk and remove all the found duplicates and that’s what this article is about.

But How do we do it?

If we were to read the whole file and then compare it to the rest of the files recursively through the given directory it will take a very long time, then how do we do it?

The answer is hashing, with hashing can generate a given string of letters and numbers which act as the identity of a given file and if we find any other file with the same identity we gonna delete it.

There’s a variety of hashing algorithms out there such as

  • md5
  • sha1
  • sha224, sha256, sha384 and sha512

#python-programming #python-tutorials #learn-python #python-project #python3 #python #python-skills #python-tips

How To Compare Tesla and Ford Company By Using Magic Methods in Python

Magic Methods are the special methods which gives us the ability to access built in syntactical features such as ‘<’, ‘>’, ‘==’, ‘+’ etc…

You must have worked with such methods without knowing them to be as magic methods. Magic methods can be identified with their names which start with __ and ends with __ like init, call, str etc. These methods are also called Dunder Methods, because of their name starting and ending with Double Underscore (Dunder).

Now there are a number of such special methods, which you might have come across too, in Python. We will just be taking an example of a few of them to understand how they work and how we can use them.

1. init

class AnyClass:
    def __init__():
        print("Init called on its own")
obj = AnyClass()

The first example is _init, _and as the name suggests, it is used for initializing objects. Init method is called on its own, ie. whenever an object is created for the class, the init method is called on its own.

The output of the above code will be given below. Note how we did not call the init method and it got invoked as we created an object for class AnyClass.

Init called on its own

2. add

Let’s move to some other example, add gives us the ability to access the built in syntax feature of the character +. Let’s see how,

class AnyClass:
    def __init__(self, var):
        self.some_var = var
    def __add__(self, other_obj):
        print("Calling the add method")
        return self.some_var + other_obj.some_var
obj1 = AnyClass(5)
obj2 = AnyClass(6)
obj1 + obj2

#python3 #python #python-programming #python-web-development #python-tutorials #python-top-story #python-tips #learn-python