#rordeveloper

Rails console is an IRB session built into the rails environment and can be operated by typing "rails c" in the terminal. It can be utilized to test connection methods, validations and check error messages while building a Rails application.

To start the rails console, run the following command run on the terminal.

$ rails console

Create a user, using the User.new command. For efficiency and ease of convenience, use a variable to store the data of the new user. Create a new user variable and assign it to the User.new, for e.g: user = User.new. The return value will be the user with no attributes i.e

user_id = nil,

name =nil.

What is validation?

Validation is used to ensure that only accurate data is stored in the database. These database-agnostic cannot be avoided by the end-users and are very convenient to test and maintain.

What is form validation?

Form validation is a technical method in which a web form validates and checks whether the information provided by a user is accurate or not. If the data provided by the user is correct according to the input format only then the user can continue with the process, otherwise, the user is required to fix the mistake to proceed.

An Introduction to RabbitMQ:

RabbitMQ is a message broker software in Ruby on Rails development where web applications connect to the queue and transfer a message onto it. When one application server sends the request to another application server, RabbitMQ works as a queue manager where requests handled and served one by one. Message transferring is done from one application to another through RabbitMQ.

RabbitMQ uses the standard Advanced Message Queuing Protocol (AMQP) to keep message request in queues and serve easily. The message may contain any information like simple text transfer or task that need to process on another server. This RabbitMQ software saves messages in a queue and keeps in a queue until receiving application get connected and start processing the messages.

Why should we use RabbitMQ in Ruby on Rails Development?

Message broker works on the producer, broker, and consumer logic. Message broker server allows consumer and producer server to respond request fast instead of using resources heavily at one time. The message broker is used to optimize the load on the server and provide services until application executes the task on the requested server. The requested server can be any third party application which performs the task.

Queued messages will be used to send the messages or task to multiple recipients from consumption that leads to the load balancing on the producer and consumer server.

Let take an example of ruby on rails server and bitcoin exchange server (i.e. bitcoind) for btc transaction working.

I have rails server running as producer and bitcoind server as a consumer.

Rails server send multiple request to bitcoind server continuously. There may be chances to slow down bitcoind because of multiple requests send to bitcoind server to process task.

In that case, RabbitMQ can fulfill the role of load balancing and messages passing by keeping the request coming from rails server in a queue and serve request one by one to bitcoind server.

Bitcoind server will take a task from the queue and start processing.

                                                       AMQP role in RabbitMQ:

AMQP store and forward messages to consumers, same as SMTP protocol which is used to deliver mail to mailboxes. Messages start from producer application to the exchanges that help to redirect in queues. Lastly, queues deliver task to the consumer application. It's now consumer's server responsibility to take the messages from queues to process as required.

A virtual channel is used to establish the connection between publishing messages from the queue. All process exchanges done over the channels.

How to use RabbitMQ in Rails application?

Using Bunny ruby RabbitMQ client, we can integrate RabbitMq with rails application. There are some gems available to start with RabbitMQ in ruby like

gem “bunny”

Bunny help rails application to interoperate with the consumer application, it can be built in any technologies irrespective of the size and complexity of the application. Also, add anampq gem in rails Gemfile to use AMQP protocol services.

  gem  ‘amqp’

RabbitMQ installation commands in Ubuntu:

1] Step 1: Update system  

sudo apt-get update

2] Step 2: Install Erlang

RabbitMQ is written in Erlang, you need to install Erlang before you can use RabbitMQ:

a] wget http://packages.erlang-solutions.com/site/esl/esl-erlang/FLAVOUR_1_general/esl-erlang_20.1-1~ubuntu~xenial_amd64.deb

b] sudo dpkg -i esl-erlang_20.1-1\~ubuntu\~xenial_amd64.deb

3] Step 3: Install RabbitMQ

     sudo apt-get installrabbitmq-server

4] Step 4: Start the Server

  sudo systemctl start rabbitmq-server.service

  sudo systemctl enable rabbitmq-server.service