Ravindra Ranwala's Blog

Introduction Today we are going to take a look at Reactive Programming using Java8 and RxJava, which is a library for composing asynchronous and event-based programs by using observable sequences. RxJava stands for Reactive Extensions for the JVM. It extends the observer pattern [Gamma95] to support sequences of data/events and adds operators that allow you to compose sequences together declaratively while abstracting away concerns about things like low-level threading, synchronization, thread-safety and concurrent data structures [1]. Pre-Requisites : Having a good knowledge about Java8, Functional Programming and spring boot microservices. What is Reactive programming? In essence, Reactive programming is an asynchronous programming paradigm concerned with data streams. The system time, a list of entries from the DB/API, user clicks, everything can be a stream of data. Data from different streams can easily be combined and transformed, and in the end processed/observed by the

Introduction Typical processing patterns on collections were very hard up until Java 8 introduced a new abstraction called a Stream. Stream operations are chained together into pipelines. Other than that lambda expressions (JSR335) facilitate functional programming and simplifies the development a lot. Workshop For an example consider the following real world use case. Suppose we have university system where an instructor can deliver questions (multiple choice) to students. Then students start responding the question with answers. The instructor needs to find following abstract information out of all the responses. Percentage of correct responses. Assuming that the multiple choice question has four answer options, how many students have chosen each option. If you implement this by following orthodox way, you may end up with many lines of code  blocks. That’s where Java8 comes to the rescue. By combining Java8 streams and lambda functions you can write each usecas

Introduction JMS is a messaging API implemented to communicate between two or more java clients using an enterprise messaging system. Java client components can use JMS API to communicate with other distributed Java clients while maintaining a loosely coupled, asynchronous connection. Therefor JMS API is well known and most often used as a message communication methodology. JMS 1.1 was introduced in 2002 and it remained unchanged until 2013, wherein the JMS 2.0 was introduced. In order to cater for todays message communication requirements, JMS 2.0 address many issues and shortcomings that was there with 1.1. Mainly JMS 2.0 introduces a simplified API in order to reduce the amount of code that needs to be written by the programmer. Even though the code lines are reduced, all the classic API functionalities are still available with JMS 2.0 simplified API. ( with JMS 2.0 programmer can decide which API to use classic or simplified, because both are available with JMS 2.0)