Roy Tutorials

Introduction I will discuss here how singleton instance works across JVM, server (for example, Tomcat, WebSphere) and clustered environments. The acronym JVM stands for Java Virtual Machine. Singleton instance generally created from singleton design pattern. The purpose of the singleton design pattern is to create a single instance from a class per application per JVM. So there is only one…

Introduction In this post we are going to see how to give users opportunity to remember their login credentials through cookie so that next time they try to login to the application do not require username and password for login. In our previous tutorials we have seen how to login and logout from an application using the following examples: Python…

Introduction In this tutorial we will see how to perform voice recording through microphone for arbitrary time using PyAudio in Python. PyAudio provides Python bindings for PortAudio, the cross-platform audio I/O library. You can easily use Python with PyAudio to play and record audio on a variety of platforms. This application does not use UI or frontend to start and…

Introduction In this post we will create a simple example in Spring Integration with greeting message or hello message. Spring Integration aims to provide a clear line between code and configuration. The components provided by the framework, which often represent the enterprise integration patterns, are typically configured in a declarative way using either XML or Java annotations as metadata. We…

Boundary in Form Data I am going to discuss here what is boundary in multipart/form-data which is mainly found for an input type of file in an HTML form. The boundary is included to separate name/value pair in the multipart/form-data. The boundary parameter acts like a marker for each pair of name and value in the multipart/form-data. The boundary parameter…

Java Class Loaders You will see here what are the Java class loaders with simple example. Java publicly released in the year of 1995 with a web browser with the ability to automatically and dynamically download applets whenever it encounters <Applet> tag in the HTML document. Such Applets are loaded on the fly across the network from remote web servers…

Introduction Here we will create an example on JAX-WS SOAP Webservice authentication using Spring Boot framework. User needs to pass username and password in the header to authenticate a user before he or she can access the JAX-WS SOAP Webservice. We will apply two approaches to publish our endpoint using Apache CXF Spring Boot starter or JAX-WS Spring API. We…

File(s) Upload I will create an example here and I will show you how to upload single file or multiple files using AJAX and jQuery along with Python Flask technologies. You can either upload single file using browse button or multiple files using browse button by holding CTRL key(in Windows OS) from keyboard while selecting multiple files. The file or…

Introduction Here you will see an example on how to exclude category from WordPress category widget. I am not going to use any plugin to exclude categories from WordPress category widget. For a simple change it is not recommended to use plugin because, using plugin your site’s overall page speed may decrease. As a side effect your site’s performance will…

Introduction We will create REST APIs to allow users login and logout from an application using Python and Flask. We have seen in another tutorial how to login and logout from an application where UI or front end was built using flask template file but here we are not providing any UI or front end but UI or front end…