A chat application allows users to communicate with others via texting, messaging, video and audio conferencing. While developing a web application web masters always think that they should communicate with their audience directly rather than emails, phone or contact forms, or chat applications can be used in various web applications such as social networking sites, business sites for live support etc.We understand the needs of webmasters and that’s why we searched and explored myriad of Google’s pages to find out these 5 free open source chat applications, webmasters can us...

Recently I saw somebody asked a question in a forum, the question is "Which programming language should I learn first?". Then someone answered this question. His answer:Depends.To program in an expressive and powerful language: PythonTo get a website up quickly: PHPTo mingle with programmers who call themselves “rockstars”: Ruby.To really learn to program: C.To achieve enlightenment: Scheme.To feel depressed: SQLTo drop a chromosome: Microsoft Visual BasicTo get a guaranteed, mediocre, but well paying job writing financial applications in a cubicle under fluorescent lights: Ja...

In Java, String.length() is to return the number of characters in the string, while String.getBytes().length is to return the number of bytes to represent the string with the specified encoding. By default, the encoding will be the value of system property file.encoding, the encoding name can be set manually as well by calling System.setProperty("file.encoding", "XXX"). For example, UTF-8, Cp1252. In many cases, String.length() will return the same value as String.getBytes().length, but in some cases it's not the same.String.length() is the number of UTF-16 code units needed to represent the s...

In HTTP header, there is a field named Referer which is to provide the referrer of the current accessed page. In this post, we will introduce the usage of HTTP referer field.On the web, when a user visits a webpage, s/he must be from some place. This place is usually referred a s referer. This information is very important to some website operators and server owners as they want to know where they get the traffic from and this helps them provide better service for potential targeted users.In the request header of a HTTP request, there is a Referer filed which can be set to the referrer URL ind...

Usually, image processing software will provide blur filter to make images blur.There are many algorithms to implement blur, one of them is called Gaussian Blur Algorithm. It utilizes Gaussian distribution to process images.This article is to introduce Gaussian Blur algorithm, you will find this is a simple algorithm. In fact, it is a kind of data smoothing which can be used in many situations.1. Gaussian Blur theoryThe so called blur can be understood as taking a pixel as the average value of its surrounding pixels.On the above graph, 2 is the center point, the surrounding points are 1.The ce...

By default, VirtualBox only allows to install 32 bit OS on it. But sometimes, 64 bit OS is wanted for specific uses such as running platform specific tests. To allow installing 64 bit OS on VirtualBox. Below information is needed.Here is the official documentation about 64 bit OS:VirtualBox supports 64-bit guest operating systems, even on 32-bit host operating systems, provided that the following conditions are met:You need a 64-bit processor with hardware virtualization support (see the section called “Hardware vs. software virtualization”).You must enable hardware virtualization ...

When maintaining code using version control systems such as git, it is unavoidable that we need to rollback some wrong commits either due to bugs or temp code revert. In this case, rookie developers would be very nervous because they may get lost on what they should do to rollback their changes without affecting others, but to veteran developers, this is their routine work and they can show you different ways of doing that.In this post, we will introduce two major ones used frequently by developers.git resetgit revertWhat are their differences and corresponding use cases? We will discuss them ...

Since the trade war between China and US, lots of services are not allowed to be used on Huawei devices as a series of procedures enforced by US government to restrict China. These services include the Google Play services which are used for downloading Android apps on Android devices. This has brought big trouble to Huawei users as they are not able to download apps available for all other Android devices. Fortunately, there are ways for people to get Google services installed on Huawei devices with some more steps after getting a new Huawei device. In this post, we will show how to inst...