Engineering

Collecting a payment sounds like a reasonably well-defined problem. A traveler pays for a booking, the payment succeeds, and the property manager receives the money. Read on →

In the previous blog post, we covered our story of migrating a giant database of almost 11 TB. Here comes the last part of the series—making Ruby on Rails applications work with RDS Proxy. Read on →

In the previous blog post, we covered our story of migrating to AWS RDS using AWS Database Migration Service (DMS), a complex initiative with multiple issues we had to address. Read on →

In the previous blog post, an intro to our database migration series, we promised to tell the story of our challenges with AWS Database Migration Service, which turned out to be far from all sunshine and rainbows as i... Read on →

In recent months, one of our most significant initiatives was migrating from our self-managed PostgreSQL clusters to the managed service on Amazon - AWS RDS. Overall, we managed to migrate 5 database clusters of 54 ap... Read on →

In the previous blog post, I promised we would introduce something special this time. So here we go - meet almighty Dionysus, who knows how to make the most of Kafka. Read on →

In the last blog post, we covered some fundamental concepts about Kafka. This time, let’s discuss how we use Kafka in Smily, how we got where we are now, what the decision drivers were, and how the overall architectur... Read on →

In the last blog post, we covered a general overview of integration patterns for distributed architecture, and now it’s time to get into further details. Read on →

Distributed architectures have been growing in popularity for quite a while for some good reasons. The rise of cloud services making the deployments simpler, as well as the ever-growing complexity of the applications,... Read on →

We’ve finally launched Smily (formerly BookingSync) Engineering Blog which I’m going to primarily focus on instead of this blog here. If you enjoyed the content of my personal blog, make sure to check Smily blog as it... Read on →

Recently, in BookingSync, we were performing a migration from Karafka 1.4 to 2.0, which we use for communication with Kafka. One of the great features available in version 1.4 was a custom partition assignment strateg... Read on →

Service objects and/or after_commit callbacks are ubiquitous in most real-world Rails applications. Whether it’s a good idea or not (ActiveRecord callbacks - I’m looking at you) is a different story, but one thing tha... Read on →

Recently, I’ve had an unfortunate opportunity to deal with a very unexpected issue with Kafka that had quite terrible consequences. The exact origin of the issue is yet to be discovered; nevertheless, the process lead... Read on →

Imagine that you are building a separate application for your e-commerce system dedicated to business intelligence. In other words, you want to calculate some stats for the orders. So you are going to create some new ... Read on →

This is the fourth and also the last part of the Kafka For Rubyists mini course. If you are interested in other parts of the course, please check them out here. Read on →

This is the third part of the Kafka For Rubyists mini course. If you are interested in other parts of the course, please check them out here. Read on →

This is the second part of the Kafka For Rubyists mini course. If you are interested in other parts of the course, please check them out here. Read on →

This is the first part of the Kafka For Rubyists mini course. If you are interested in other parts of the course, please check them out here. Read on →

I’ve been recently planning to record a couple of tutorials for my team in BookingSync, focusing mostly on monitoring and some other more advanced aspects of Kafka and Karafka. But if I was already recording something... Read on →

If you’ve ever had a need to implement an audit log to track all the changes that get persisted for all or at least some models in your application, there is a good chance that you’ve encountered PaperTrail gem that m... Read on →

Imagine that you are implementing a payment processing system for the e-commerce system and discover that multiple customers were charged twice for exactly the same order. Ouch… Sounds like a real nightmare to deal wi... Read on →

Communication between two or more applications is often everyday stuff, and it might seem that there is not too much to add there as this subject has been covered pretty well in the last years. Thanks to that, multipl... Read on →

Imagine that you are working on a large legacy application that also contains the dreaded ActiveRecord callbacks in the models handling most of the business logic. At some point, and under a certain level complexity, ... Read on →

Sidekiq is one of the most popular (if not the most popular one) background job framework in Ruby world, which is not a big surprise: it allows to achieve a decent throughput, is stable and well-maintained, has some g... Read on →

In the first part of this series, we were exploring some potential options for communication between services - what their advantages and disadvantages are, why HTTP API is not necessarily the best possible choice and... Read on →

In the first part of this series, we were exploring some potential options for communication between services - what their advantages and disadvantages are, why HTTP API is not necessarily the best possible choice and... Read on →

Microservices, Service-Oriented Architecture (SOA) and in general, distributed ecosystems, have been on hype in the last several years. And that’s for a good reason! At certain point, The Majestic Monolith “pattern” m... Read on →

It is sometimes required for the methods with optional arguments to be able to differentiate between its default value and the value passed from the caller. Passing nil might initially sound like a good idea since it ... Read on →

Imagine that you are implementing some form object because you are fed up with treating ActiveRecord models as such, and you need some extra flexibility. You start with a straightforward implementation for a base clas... Read on →

In the typical Rails application, you can find the most of the validations in the ActiveRecord models, which is nothing surprising - ActiveRecord models are used for multiple things. Whether it is a good thing, or a b... Read on →

Optimizing database queries is arguably one of the fastest ways to improve the performance of the Rails applications. There are multiple ways how you can approach it, depending on the kind of a problem. N+1 queries se... Read on →

If you’ve ever worked with JavaScript, especially in pre-SPA/pre-frameworks era with just jQuery, you probably had a chance to see an “exotic” maths in action that looks similar to this: Read on →

Adding consents for accepting Terms of Service/Privacy Policies must have been a top popular feature in the majority of the applications due to enforcement of GDPR in May ;). From the technical aspects that GDPR requi... Read on →

Few months ago I wrote a blog post about ActiveRecord before_validation callback and how it is used for wrong reasons and concluded that in most cases this is not something we should be using routinely. However, I mi... Read on →

A great advantage of using Ember Data with JSONAPI-compliant adapters/serializers is that there is almost nothing extra needed to work with the data layer - just create the models with names matching the types of the ... Read on →

Ruby has quite a lot of “exotic” features that are not used that often, but when you need to utilize some metaprogramming magic, you can easily take advantage of them. One of such features is Object.instance_exec whic... Read on →

Touching ActiveRecord models is quite a common thing in most of the Rails applications, especially useful for cache invalidation. By default, it updates updated_at timestamp with the current time, Here’s a typical exa... Read on →

Imagine that you are implementing an e-commerce platform and want to grab all orders from the current year. What would be the simplest way of doing it in Rails? Probably writing a query looking like this: Read on →

Recently, I’ve had quite a popular problem to solve: count the occurences of the given item in a collection. There are few ways to solve this problem - starting from using Enumerable#inject or Enumerable#each_with_obj... Read on →

One very useful feature of ActiveRecord is automatically defining attribute readers and writers for all the columns for given tables. For the ones with boolean type, however, there is one more addition - defining an a... Read on →

It’s nothing new that ActiveRecord callbacks are abused in many projects and used for the wrong reasons for many use cases where they can be easily avoided in favor of a much better alternative, like service objects. ... Read on →

Object#try is quite a commonly used method in Rails applications to cover cases where there is a possibility of dealing with a nil value or to provide flexible interface for handling cases where some kind of object do... Read on →

As hard as it is for me to believe, I already have over 5 years of professional experience in Ruby and Rails. Throughout all these years my attitude towards Rails has been fluctuating between going from blind love to ... Read on →

Ember.js is a web frontend framework and it’s no surprise that majority of the applications deal with a lot of HTTP requests. But such fact has a lot of implications on the process of development of the Ember apps, es... Read on →

In the majority of the Rails applications or even Ruby gems you can find a lot of use cases where you need to memoize a result of some computation for performance benefits and to not compute it again if this result ha... Read on →

Timeouts and delays are quite extensively used in many applications when deferring execution of some action via Ember.run.later or debouncing via Ember.run.debounce. Having small amounts of tests executing such method... Read on →

Thanks to the awesome tools in Ember ecosystem such as ember-cli-mirage, ember-qunit or ember-test-helpers writing majority of the tests is pretty straight-forward. Nevertheless, there are quite a few cases where simu... Read on →

Imagine a use case where you are trying to check if a user accessed your app from a mobile device or not. Most likely you will need to use navigator.userAgent property and craft some smart regular expression to test ... Read on →

Do you think you know all the surprising parts of JavaScript? Some of these "features" may look as if the language was broken, but it's not necessarily the case. Things like variables hoisting, variables scope, behavi... Read on →

Arrow function expressions were definitely a great addition in ES6 and thanks to tools like babel the new syntax has been quite widely adopted. Besides more concise syntax, an interesting thing about arrow function ex... Read on →

Rails 5.0 is without a doubt a great release with plenty of useful changes and additions. The most notable change was probably ActionCable - the layer responsible for integrating your app with websockets. However, the... Read on →

Soft delete is a pretty common feature in most of the applications. It may increase complexity of the queries, nevertheless, not deleting anything might be a right default as the data might prove to be useful in the f... Read on →

Executing background jobs is quite a common feature in many of the web applications. Switching between different background processing frameworks used to be quite painful as most of them had different API for enqueuin... Read on →

Every now and then I discover some features in Rails that are not that (arguably) commonly used, but there are some use cases when they turn out to be super useful and the best tool for the job. One of them would defi... Read on →

Have you ever wondered how it is possible that calling class methods on mailers work in Rails, even though you only define some instance methods in those classes? It seems like it’s quite common question, especially w... Read on →

After publishing recent blog posts about table partitioning - its SQL basics part and how to use in in Rails application I was asked quite a few times what is the real performance gain when using table partitioning. T... Read on →

In the previous blog post we learned some basics about table partitioning: how it works and what kind of problems it solves. So far we've been discussing mostly basic concepts with raw SQL examples. But the essential ... Read on →

You've probably heard many times that the database is the bottleneck of many web applications. This isn't necessarily true. Often it happens that some heavy queries can be substiantially optimized, making them really ... Read on →

Is validation in your models or form objects enough to ensure integrity of the data? Well, seems like you can't really persist a record when the data is not valid unless you intentionally try to bypass validation usin... Read on →

I was recently asked what is secret key base used for in Rails applications and why not secure value of it (or even worse - the public one!) creates a security issue. That was a really good question, I remember how it... Read on →

Ordering with ActiveRecord and PostgreSQL may seem like an obvious and simple thing: in most cases you just specify one or several criteria with direction of ordering like order(name: :asc) and that's all, maybe in mo... Read on →

In my recent post I mentioned some strategies of handling non-strictly CRUD / RESTful actions in API. One of them was adding extra actions beyond creating, updating and deleting resources. As it's not a standard solut... Read on →

If you happen to develop API for non-trivial app with complex business logic beyond CRUD directly mapped to the database tables (i.e. typical Active Record pattern) you were probably wondering many times how to handle... Read on →

Having some kind of type attribute in your models is a pretty common thing, especially in applications with more complex domain. How do you handle such cases? Is it with multiple conditionals / case statements in ever... Read on →

In the previous blog post we were exploring a new wonderful feature coming with ECMAScript 7: decorators. This time we are going to learn about async / await, which is at this moment at Stage 3 in TC39 process, which ... Read on →

ES6 introduced plenty of useful features such as modules, arrow functions, let variables, destructuring, classes and many more which made writing JS code much readable and enjoyable. Thanks to Babel, a JavaScript tran... Read on →

Recently I've been repeatedly asked how to get started with programming, especially Ruby and Rails. To keep things DRY and make sure I always include all great resources for learning, I decided to write this blog post... Read on →

In many Rails applications the modeling is limited only to creating classes inheritng from ActiveRecord::Base which are 1:1 mapped to database tables. Having AR models like User and Project doesn't tell much about the... Read on →

There've been a lot of discussions for several months about "The Rails Way" and problems associated with it - huge models with several thousands lines of code and no distinguishable responsibilities (User class which ... Read on →

You've started developing new app and need server to deploy it. You can choose hosting platform like Heroku or Shelly which may turn out to be quite expensive if you want to host multiple apps. You can also set up you... Read on →

You are working currently on that awesome app and just started thinking about implementing new feature, let's call it feature X. What's the first thing you do? Rolling your own solution or... maybe checking if there's... Read on →

Last time, in part 1, I was giving some advice about testing - why to test at all, which tests are valuable and which are not, when to write acceptance tests and in what cases aim for the maximum code coverage. It bro... Read on →

Testing is still one of the hottest topics when it comes to developing maintainable and business-critical applications. Ruby on Rails community embraces the importance of writings tests, yet there are so little resour... Read on →

There’ve been a lot of discussions recently about applying Object Oriented Programming in Rails applications, how ActiveRecord callbacks make testing painful and how Rails makes it hard to do OOP the right way. Is it ... Read on →

You've just setup your production server, but still haven't deployed your app? Then this the right place for you. You are going to learn how to deploy your app to remote server, deal with some config files, create sta... Read on →

Server setup with the entire environment for Rails applications can be quite tricky, especially when you do it for the first time. Here is step by step guide how to setup CentOS 6.4 server with a basic environment for... Read on →