There’re many PLC application examples available around us. As long as everything is automated and people won’t need to constantly control the whole operation, they have implemented PLC operation into their daily production. Lots of people think that PLC application is always grandeur and big while having smaller scale PLC operation is also possible.
![rack app example rack app example](https://kubernetes.io/images/blog/2020-05-05-introducing-podtopologyspread/api.png)
There’re many good examples people can see of how PLC system should be used and how it can be set and adjusted. PLC system and operation have been around for quite a long time.
![rack app example rack app example](https://i.pinimg.com/originals/2f/47/14/2f471498e8a9e5c02161cdc306463358.jpg)
As these application servers work for any Rack app, your small app will work as seamlessly as when using Rails.When people want to know more about PLC operation, they can view the already existing PLC application examples. In these cases, you can just create your very own Rack application and serve it in the Internet through Unicorn or Puma. If you are building a simple web application, you may find that using a full-fledged framework like Rails is overkill. As developers, it is important for us to understand how it works so we can use it as an additional tool in our arsenal. Rack is an important foundation for web application frameworks in Ruby. Use ActiveRecord::Migration::CheckPendingĪs we can see, Rails uses several Rack middleware to handle certain features, such as: Use ActiveSupport::Cache::Strategy::LocalCache::Middleware To show the middleware that a Rails application uses, run this command: > rails middlewareįor a default Rails 6 application, it will return these values: use ActionDispatch::HostAuthorization The Ruby on Rails framework, a Rack application itself, uses several middleware to extend its functionality.
#RACK APP EXAMPLE UPDATE#
These extensions are called Rack middleware, and are invoked by the use syntax, as shown below: use SecondMiddlewareĪs a middleware has access to the request data and can update the HTTP status and response body, certain features common in a web application are best handled using a middleware, such as: This is a powerful concept as we can easily extend the functionality of an application by stacking other Rack apps. Since they are all conforming to a fixed API, they can be connected, or stacked, on top of one another. MiddlewareĪnother useful feature of Rack applications is extensibility. This is a contrived example but it illustrates how we can extend the functionality of our simple Rack application to handle different scenarios based on the request.
#RACK APP EXAMPLE CODE#
To illustrate this, the code below shows a simple Ruby class that conforms to the above, and is therefore a valid Rack application.
#RACK APP EXAMPLE SERIES#
But do you know the layer beneath that framework? Are you aware that these frameworks use a mini-framework within? As part of the series on Web Application Basics, we will introduce Rack and why it is important for developers to know how it works. Knowledge of these frameworks enable developers to create feature-rich web applications in a short amount of time.
![rack app example rack app example](https://mediadl.musictribe.com/media/PLM/data/images/products/P0AWN/2000Wx2000H/X32-RACK_P0AWN_Front_XL.png)
These frameworks make our lives much easier due to the built-in features, conventions that allow others to easily understand our code, and the use of the vast Ruby ecosystem.
![rack app example rack app example](https://files.speakerdeck.com/presentations/045aa390ad28013183613ab2b4f1ac72/slide_14.jpg)
As Ruby developers, we are familiar with popular web frameworks such as Rails, Sinatra and Hanami.