Today we gonna talk about Decorator Pattern. Every morning, before starting work I drink coffee, sometimes with milk, sometimes with a bar of chocolate. Let’s imagine the business that seels coffee asked us to write software that will help them selling different types of coffee (Coffe with Milk, Coffe with Chocolate, Coffe with Milk and […]
This article will be pretty short. Imagine you have a weather station and you should provide weather info for other businesses and government alerting system (they will use this information for informing people). For implementing this we will use Observer pattern. Observer pattern has two parts Observable and Observer. Observable is the weather station that […]
I will start with a simple example where we want to have an AbstractBuilder for building Pet instances, in our example this will be a Dog. Here are the Pet class, and the Dog class that extends Pet Suppose we need a builder for building Dog instances and we know that in future there will […]
The Unit return type declaration is optional for functions. The following codes are equivalent. Single-Expression functions:When a function returns a single expression, the curly braces can be omitted and the body is specified after = symbol fun sum(a : Int, b : Int) : Int = a + b Explicitly declaring the return type is […]
Hello World Kotlin programs start at the main function. Here is an example of a simple Kotlin “Hello World” program: When compiled this code will be compiled into a file named after file name + ‘Kt’, if your file was named Main.kt, the compiled code will be in a file name MainKt. In the above […]
When writing software, it is important to keep you organized and focused, losing focus or vague understanding requirements will endup in a bad written system in the best case. If you have got a large body of work that needs to go into production there are lots potential thinks that can go wrong. When you […]
In this article I would like to explain what kind of problems can we encounter when working with Apache Kafka and how we can address them. Apache Kafka is a distributed streaming platform, it is used for building real-time data pipelines, because of persistence of topics it can be used for processing historical message events; […]
S3Fuse allows you to mount an S3 bucket to your local storage and interact with it like it was stored into your local storage. It is written in Java and it will be published to my github account soon. It allows to read data from S3 but it is not possible yet to write data […]
Recently I run into a problem where hashing some data had a big impact on the application performance. There are few factors that influenced this but it required 2.5x more instances, imagine when you have 15 instances of you application in production and it requires 38 to serve the same traffic. In order to understand […]
The purpose of this article is to explain (mainly to myself) a technique for creating good indexes for mysql database. Before starting I would like to discuss about selectivity. Index selectivity is the ratio of number of distinct indexed values ( the cardinality) over the total numbers of rows in the table (#T), and ranges […]