Thursday 25 May 2017

PHP, ASP.NET, JSP, Python - which server side script is better for you?

PHP, ASP.NET, JSP, Python - which server side script is better for you?
When you type in a URL, lots of code is at work to bring a page to your screen. What connects your site’s database to the browser, creating a smooth, user-friendly experience? That’s the software built by server-side scripts, languages that build your site behind the scenes.

Server-side scripting is a technique used in web development which involves employing scripts on a web server which produce a response customized for each user's request to the website. Now a days, there have lot of server side languages for web development. Here is the few of them -

PHP - The most popular server-side language on the web, PHP is designed to pull and edit information in the database. PHP is an extremely capable language, with a vast array of built-in functions to do everything from tracking user sessions to generating dynamic graphics and even PDF files. No modules to install, no commercial add-ins to buy, but is also used as a general-purpose programming language. PHP is free, cross-platform, Open Source software. It integrates with all major Web servers on all major operating systems. This is a great boon for developers on a budget, because they can set up a complete Linux-based Web server with PHP support.

Python - Python is a widely used high-level, general-purpose, interpreted, dynamic programming language. It is fast with fewer lines of code, making it ideal for getting things to market quickly. The emphasis is on readability and simplicity, which makes it great for beginners. It's the oldest of the scripting languages, is powerful, and works well in object-oriented designs.

ASP.NET - ASP.NET is an open-source server-side web application framework designed for web development to produce dynamic web pages. This Microsoft framework is the most popular enterprise-level framework. It supports multiple programming languages simultaneously for one project. So, the same application can be built with both C# and C++, via CLI (common language interface). It's most recent iteration, ASP.NET 5, is now open to non-Windows platforms for the first time.

JSP - Java Server Pages is a technology that helps software developers create dynamically generated web pages based on HTML, XML, or other document types. A subset of the C language, Java comes with a huge ecosystem of add-on software components. At its core, Java is a variation of C++ with an easier learning curve, plus, it's platform independent thanks to the Java Virtual Machine. "Compile once, run anywhere" is its motto. it's excellent for enterprise-level applications, high-traffic sites, and Android apps.

So, which one is better for your website development?
All the server side scripting languages have their own advantages and disadvantages. But compared to ASP.NET, Python and JSP it is better to start with PHP. PHP has an easier learning curve, it has a larger community-base for support and it's cheaper to get hosting. However it is not considered by many as being of "enterprise quality". JSP is an alternative to PHP like any other programming language, and just like PHP is an alternative to anything other. But JSP is harder to learn, smaller community-base for support and hosting is generally not cheap.

However, once you start going more advanced and bigger, PHPs agility instead becomes it's own worst enemy, and you have to do a lot of extra coding to get the infrastructure needed that JSP and .NET already has in place from the beginning. PHP is also very problematic in the sense that it completely lacks a standard approach to development, which causes loss of time when you are dealing with many developers.

In case of Python, day by day it getting more popularity. It can be used for almost any imaginable task except, perhaps, for highly intensive cpu bound applications, since it's currently not as fast as other languages but, if performance is critical, you still have many options and tools to help you get the most out of python. It's readable, very easy to learn and use, flexible and very expressive. All these characteristics make it a very productive language. Python also great for startups, because it's highly productive and allows a more exploration way of coding which is awesome when prototyping or trying out new ideas. Often, these prototypes get shipped as the final, production version.

Hope all this points help you to choose a better server side scripting language for your web development projects.

Sunday 21 May 2017

What is JavaScript?

What is JavaScript?
As per Wikipedia, JavaScript is a high-level, dynamic, untyped, and interpreted programming language. Alongside HTML and CSS, it is one of the three core technologies of World Wide Web content production. The majority of websites employ it and it is supported by all modern Web browsers without plug-ins. It also support object-oriented, imperative, and functional programming styles. It has an API for working with text, arrays, dates and regular expressions, but does not include any I/O, such as networking, storage, or graphics facilities, relying for these upon the host environment in which it is embedded.
Why every programmer should learn JavaScript?

Demand - As per GitHub and StackOverflow, JavaScript is more popular than any other languages and number one computer language  till date. JavaScript's matures and things like Node.js become increasingly viable options, the demand for JavaScript programmers will continue to increase.  JavaScript already surpasses C# as rated by demand, and is surpassed only by Java.

Higher paid - JavaScript pays better than C# but still Java pays a bit better right now. But as demand for JavaScript grows, we can expect the pay to increase as well. While the demand for JavaScript is evident, it is obvious that several languages that have a smaller demand actually pay better. I suspect this is because many organizations still think of JavaScript as the language that anyone can use.  It will be a very painful lesson when they find out that "Anyone can program in JavaScript" really means, "Anyone can write crappy code in JavaScript".

JavaScript is Maturing - With the recent commitment of the standards committee to release a new JavaScript standard every year, it is clear that the amount of Syntactic Sugar that will be added on to JavaScript is going to be increasing every year for a while now.  One of the best features JavaScript is the ability to use the async and await keywords in code to eliminate callback hell.

The browsers are also continually improving how they handle JavaScript code.  In the future when browsers not only cache the JavaScript files, but cache the compiled version of the JavaScript files.  Bringing us closer to near binary speed.

JavaScript Programmers Are More Equal Than Others - Many people who call themselves JavaScript programmers, but don't know the basics. And that is today. Imagine what this is going to look like three to five years from now. And don't forget that a lot of the tooling to support profiling and memory leaks is just at its infancy. If you have those skills today, and you have marketed yourself well, you are already realizing that a lot of what I'm saying here is true.

Frameworks Are Maturing - With the new version of Angular in the works, Aurelia in the works as an alternative. Commercial products such as Scencha's EXTjs.  Node.js for server side programing. Node.js for server side programing. And others No one can say that it is too hard to develop real applications using JavaScript. Even, you could write a desktop application that ran using nothing but JavaScript.

JavaScript Runs Everywhere - JavaScript runs on every major browser on every major platform. It runs on the server side on every major operating system.  Anyone writing a web site today of any major functionality is going to need someone who knows JavaScript to write the front end.  It doesn't matter what the back end code was written in be it Java, PHP, .NET, Node.js or something else, the client side is going to need a JavaScript developer.

JavaScript is a Compiled Language - It may shock you to know that, technically, JavaScript is a compiled language.  This has two implications.  First, once the code is compiled, it is possible for it to run as fast as any other executable.  Second, it is technically possible to write tooling for JavaScript that would create a binary file that does not need to be recompiled every time the code is loaded into memory.

JavaScript will dominate, but no one will write it - Future of JavaScript is different than others. If we don't write JavaScript, who will? Transcoding robots, that’s who. We'll write our code in any of a dozen dialects and the transcoding robots will turn it into something that the browser or Node.js understands. More and more code on GitHub can't run without being "compiled" by something. The most prominent are pinky-saving dialects, such as TypeScript and CoffeeScript, that strip away much of the punctuation that bothers some programmers. These are only the beginning because clever programmers have written transcoders for languages as diverse as Cobol, Java, Lisp, and C. All of them can now run in your browser after being lovingly translated and optimized for fast delivery and parsing.

Thursday 18 May 2017

What is phishing attack?

Phishing is a form of fraud in which the attacker tries to steal sensitive information such as usernames, passwords, and credit card details etc. The word is a neologism created as a homophone of fishing due to the similarity of using a bait in an attempt to catch a victim. The most common type of phishing scam, deceptive phishing refers to any attack by which fraudsters impersonate a legitimate company and attempt to steal people’s personal information or login credentials.
Communications purporting to be from social web sites, auction sites, banks, online payment processors or IT administrators are often used to lure victims. Typically a victim receives a message that appears to have been sent by a known contact or organization. An attachment or links in the message may install malware on the user’s device or direct them to a malicious website set up to trick them into divulging personal and financial information, such as passwords, account IDs or credit card details.

For example, PayPal scammers might send out an attack email that instructs them to click on a link in order to rectify a discrepancy with their account. In actuality, the link leads to a fake PayPal login page that collects a user’s login credentials and delivers them to the attackers.

Phishing is popular with cybercriminals, as it is far easier to trick someone into clicking a malicious link in a seemingly legitimate email than trying to break through a computer’s defenses. Although some phishing emails are poorly written and clearly fake, sophisticated cybercriminals employ the techniques of professional marketers to identify the most effective types of messages.

On the contrary, phishing is constantly evolving to adopt new forms and techniques. With that in mind, it’s imperative that organizations conduct security awareness training on an ongoing basis so that their employees and executives stay on top of emerging phishing attacks.

Wednesday 17 May 2017

What is MVC framework?

Model View Controller or MVC is a software architectural pattern for implementing user interfaces on computers. It is an architectural pattern that separates an application into three main logical components: the model, the view, and the controller. The MVC design pattern decouples these major components allowing for efficient code reuse and parallel development. Each of these components are built to handle specific development aspects of an application. MVC is one of the most frequently used industry-standard web development framework to create scalable and extensible projects.

As with other software architectures, MVC expresses the "core of the solution" to a problem while allowing it to be adapted for each system. Following are the components of MVC -


The Model component corresponds to all the data-related logic that the user works with. A model stores data that is retrieved according to commands from the controller and displayed in the view.


The View component is used for all the UI logic of the application. It generates new output to the user based on changes in the model.


Controller represents the classes connecting the model and the view, and is used to communicate between classes in the model and view. It process all the business logic and incoming requests, manipulate data using the Model component and interact with the Views to render the final output.

Monday 15 May 2017

What Is RemixOS 3.0 And How To Install It

What Is RemixOS 3.0 And How To Install It
Remix-OS_0011-1024x773 RemixOS is now making a new trend these days, so I thought to post a guide on What is RemixOS 2.0 And How To Install It On Your Computer. I think that too many people were waiting to get android interface on their PCs and that’s the reason why android emulators got so much popularity but now finally RemixOS is released for PCs to provide a perfect Android user interface to the users on a big screen. Now it’s possible to run Android operating system and all the Android apps on your PC, with the help of RemixOS, which is developed by Jide Technology.
So, now let’s get to our first question.

What Is RemixOS?

RemixOS is another brand new and very useful operating system. With RemixOS, you will be able to get android environment on your PC. This is going to be the best OS for android developers to test their apps and also for them who used Android emulators which run very slow to use some awesome android apps on PC. RemixOS will give you faster and smoother android user interface on your PC.

Hardware and Software Requirements

Jide recommends a system with the following specifications:
  • 2.0 GHz dual-core processor.
  • 2 GB of RAM.
  • 8 GB of hard drive space. (This is a hard requirement.)
  • Remix OS 3.0 32-bit (Download) or 64-bit (Download).
  • This package also contains a tool that installs Remix OS to a flash drive.
  • A formatted USB drive with at least 8 GB.
  • A second formatted USB drive with at least 512 MB or a CD/DVD (optional).
  • A computer to install Remix OS onto. (This is obvious :P)

Imaging Remix OS 3.0 on a USB Drive or DVD

Use Jide’s modified version of UNetboointo to burn the ISO of Remix OS onto a bootable drive. The program resides inside of the same package that contains the ISO file of Remix OS. The file name is “Remix_OS_for_PC_Installation_Tool”. Jide’s official instructions mention that USB 3.0 is required, but since you’ll be installing Remix onto a hard drive, you can ignore that.
Insert a USB drive (at least 8 GB) into your computer and run UNetbootin. This file is located inside of the package containing Remix OS. You will need to unzip the package, first.
After unzipping the file and running the program, first, click on Browse. Second, select USB Drive (not hard drive). Third, select the correct flash drive, if you have multiple USB flash drives inserted. Fourth, and last, click OK.


Installing Remix OS to a Hard Drive

This step is the most complicated out of all steps in this guide. First, you must boot from the drive with Remix OS installed using the appropriate F-key (normally F12). Second, highlight (but don’t initiate the installation process yet) the option for Resident mode and press E.
Remix 3.0 Installation Press E Key
You’ll see a list of Linux (or UNIX) commands. Use your keyboard’s directional keys to navigate to the entry "DATA = USB_DRIVE_1" and replace it with "INSTALL=2". It should look like this before you edit the text (To be edited text circled in red)
Remix 3.0 Installation Before Editing
After editing the text, it should look like this:
Remix 3.0 Installation After Editing
Remember that Linux is case-sensitive, so you must adhere to letter casing. After verifying that the correct command has been edited in, press F10. The installation process should begin. Installation and initial boot can take as long as 30 minutes.
Once it finishes, you’ll receive a prompt to install in English or two different dialects of Chinese. You’ll want English, most likely.

Installing the Google Play Store

Remix 3.0 includes the Play Store by default, although getting it working requires activation. If you do not possess internet access, this step won’t work. Fortunately, Remix includes all of the driver support contained in Linux.
The process is simple: double-click on the Play activator from the Remix OS desktop. From there, you’ll enter a guided activation configuration process.
Remix 3.0 Play Store Activation

Should You Install Remix OS 3.0?

If you own an old computer, then yes. Remix OS 3.0 captures everything that’s amazing about Android and makes it installable on most hardware. While it’s not completely open source, Remix’s developers fully abide by open source licensing.
Like its predecessor, Remix’s third iteration brings with it excellent app and system compatibility. Most x86 systems cannot run most Android apps because of fundamental logic differences between ARM code and x86. Remix uses a method called ARM emulation, which allows x86 systems to bypass this restriction. In a nutshell, if you love Linux’s low resource requirements, but dislike its app ecosystem, Remix OS 3.0 may win you over.
Have you tried Remix OS 3.0 yet? What were your experiences? If not, what are your thoughts on it? Let us know about it in the comment box below 🙂

Tuesday 9 May 2017

KDE vs Gnome - which one is better for you?

KDE vs Gnome - which one is better for you?

What is Desktop environment?
The term desktop environment refers to the graphical environment where you do your work. The desktop usually consists of a workspace with pretty icons and quite possibly a menu that pops up when you click on it, usually a panel on the top or the bottom and/or top of the screen with a menu and a lot of other practical services you may never even notice. The most important part of any desktop is the window manager, this is the application that handles window placements and movements. The window manager is what draws a border around your windows and makes them maximize, minimize, moves and behave according to your preferences.

There was a time when UNIX desktops were developed by big corporations. It took not just one but many large firms to come together to build a desktop for the UNIX OS. The end result was Common Desktop Environment (CDE), developed jointly by Sun Microsystems, HP, IBM and UNIX Systems Laboratories. To its credit, it was a popular desktop environment used in almost all UNIX systems, but it was not even close to fulfill decent desktop requirement for most users.

In 1996, the KDE project was started, followed a year later by GNOME, and the world of UNIX desktops changed for ever. It was quite surprising back then because neither KDE nor GNOME was a commercial project. Both started as open source, and both shared the same goal - to make Linux the best desktop operating system. But the philosophy was different. The KDE project wasn't concerned with open source idealism - that's why GNOME was born, to create a desktop environment with fully GPLed software. This philosophical disagreement led to two completely different and innovative desktop environments for Linux.

What is the better desktop environment?
Linux is like Lego. You can build your own desktop environment. Both KDE and Gnome are just big packages with software aimed to look and feel the same way, work well together and generally give you a nice experience. Linux newbies always get puzzled when the distribution's installation wizard asks them which desktop to install - KDE or GNOME. The answer is different for each individual. Linux veterans have great desktop environment brand loyalty - there is a very good chance that a KDE user will remain a KDE user, or a GNOME user will remain a GNOME user, for a long time. Both sets of users have their own set of favourite features that they are attracted to.


KDE and Gnome are complete desktop environments that consist of a large number of tightly integrated yet still separate pieces of software. Gnome usesa window manager called metacity, KDE uses kwin. Both these desktops can be used with any other window manager if you do not like the default choice.

Application that are "made for Gnome" or "made for KDE" can be used with any desktop. This only means that the program use a set of library functions found in their underlying gnome-libs or kdelibs. You do not need to use the actual desktops to use the applications, software made for KDE and Gnome can be used with any window manager / desktop as long as you got the proper libraries installed. There is no reason to use only applications made for the desktop you prefer, the "best software" for one task is made for KDE, the best for another task is made for Gnome. Use the best from both worlds.


Both KDE and Gnome can be customized to behave exactly the way you want. What desktop you prefer is your own choice and preference. When in doubt, try to learn both. Or experiment with other desktops. Remember, *nix applications are not locked to the desktop they are made for, Gnome applications can be used in KDE and vice versa. There is no "best desktop", but there is a desktop that's best for you. It's a matter of preference, and hardware.

Try them all. This is your choice. There are plenty of Live-CD Linux distributions that let you try both KDE and Gnome without installing anything at all. Knoppix is a nice alternative. Some people claim KDE is the best choice for beginners.

play Windows games on Linux

Linux operating systems gives the stability and security that Windows platform somewhere fails to deliver. But what about gaming? Linux users understand this pain. It will be a fare game to compare both on this aspect. Users who want to go with gaming will rarely use Linux and users who are comfortable with Linux operations will rarely go for Windows. Both are big competitors to each other and both have respective pros and cons. But when it comes to gaming then Windows leads Linux somewhere.
So, does this mean, can't we play games on Linux? Well it's not true and today we can easily play most of the Windows games on Linux system. Here are the some tools that will convert your Linux machine into a gaming ware.

1. Wine 

Wine is a compatibility layer which is capable of running Windows applications in systems like Linux, BSD and OS X. With the help of Wine, you can install and use a number of Windows games in Linux. WINE is a free and open source that allows Microsoft Windows to run on machines using Unix environment. WINE is quite famous for its software library Winelib which allows users to compile and port Windows apps to Unix platform.

2. PlayOnLinux

PlayOnLinux acts as the graphical front end for compatibility layer of Wine software. It is a powerful tool that allows you to club almost any Windows apps like MS Office, IE, video games with your Unix platform. It has different interface and slightly easier to use than Wine. Like Wine, PlayOnLinux too is free to use. You can browse the applications and games supported by PlayOnLinux on its database.


3. Steam

Steam is a digital distribution platform for video games. It provides you the option to buy and install games, play multiplayer and stay in touch with other games via social networking on its platform. The games are protected with DRM. A couple of years ago, when Steam announced support for Linux, it was a clear indication that gaming on Linux is being taken seriously. Though Steam's decision was more influenced with its own Linux-based gaming console and a separate Linux distribution called Steam OS

4. CrossOver

CrossOver is an improved version of Wine that brings professional and technical support to Wine. But unlike Wine, CrossOver is not free. Good thing about CrossOver is that every purchase contributes to Wine developers and that boosts the development of Wine to support more Windows games and applications.

5. VMware

VMware allows you to use popular games like WoW and SIMS on your Linux machine. So if you are looking towards playing high level games on your Linux machine then it is the best tool to go with.





These are the tools that you can try to install Windows games on your Linux machine. I think that's pretty much what you need to know to get started with gaming on Linux. If you are still not convinced, I would advise you to dual boot Linux with Windows. Use Linux as your main desktop and if you want to play games, boot into Windows.

Saturday 6 May 2017

File Uploads in Angular with a Node and Hapi Backend

In this article, we will talk about how to handle file uploads with Angular. We will create an images uploader that allow user to upload single or multiple images file by drag and drop or select file dialog.We will then upload the selected images and display them accordingly. We will also learn to filter the upload file type, for example, we only allow images, do not allow file type like PDF.
                                     Image uploader

# File Upload UI & API

File upload consists of two parts: the UI (front-end) and the API (back-end). We will be using Angular to handle the UI part. We need a backend application to accept the uploaded files. You may follow the backend tutorials or download and run either one of these server side application to handle file upload for your backend:-
We will be using File upload with Hapi.js as our backend throughout this articles. We will also learn the tricks to enable fake upload on the front-end.

# File Upload Component HTML

Alright, let's start creating our Angular file upload component.
<!-- page-file-upload.component.html -->

  <form #f="ngForm" enctype="multipart/form-data" novalidate 
    *ngIf="currentStatus === STATUS_INITIAL || currentStatus === STATUS_SAVING">
    <h1>Upload images</h1>
    <div class="dropbox">
      <input type="file" multiple
        [name]="uploadFieldName" (change)="filesChange($, $" 
        [disabled]="currentStatus === STATUS_SAVING" accept="image/*" #photos>
      <p *ngIf="currentStatus === STATUS_INITIAL">
        Drag your file(s) here to begin<br>
        or click to browse
      <p *ngIf="currentStatus === STATUS_SAVING">
        Uploading {{ photos.files.length }} files... 
  1. Our upload form will have a few statuses: STATUS_INITIAL, STATUS_SAVING, STATUS_SUCCESS, STATUS_FAILED, the variable name is pretty expressive themselves.
  2. We will display the upload form when the status is initial or saving.
  3. The form attribute enctype="multipart/form-data" is important. To enable file upload, this attribute must be set. Learn more about enctype here.
  4. We have a file input <input type="file" /> to accept file upload. The property multiple indicate it's allow multiple file upload. Remove it for single file upload.
  5. We will handle the file input change event. Whenever the file input change (someone drop or select files), we will trigger the filesChange function and pass in the control name and selected files $, and then upload to server.
  6. We limit the file input to accept images only with the attribute accept="image/*".
  7. The file input will be disabled during upload, so user can only drop / select files again after upload complete.
  8. We set a template variable #photos to the file input. This gives us a reference to the file input control. Later, you can see we use the photos variable in displaying number of files uploading Uploading {{ photos.files.length }} files....

# Style our File Upload Component

Now, that's the interesting part. Currently, our component look like this:
                                  File upload component without styling
We need to transform it to look like this:
                                     File upload component with styling
Let's style it!

/* page-file-upload.component.css */

.dropbox {
    outline: 2px dashed grey; /* the dash box */
    outline-offset: -10px;
    background: lightcyan;
    color: dimgray;
    padding: 10px 10px;
    min-height: 200px; /* minimum height */
    position: relative;
    cursor: pointer;

.dropbox:hover {
    background: lightblue; /* when mouse over to the drop zone, change color */

input[type="file"] {
    opacity: 0; /* invisible but it's there! */
    width: 100%;
    height: 200px;
    position: absolute;
    cursor: pointer;

.dropbox p {
    font-size: 1.2em;
    text-align: center;
    padding: 50px 0;
With only few lines of css, our component looks prettier now.
  1. We make the file input invisible by applying opacity: 0 style. This doesn't hide the file input, it just make it invisible.
  2. Then, we style the file input parent element, the dropbox css class. We make it look like a drop file zone surround with dash.
  3. Then, we align the text inside dropbox to center.

# File Upload Component Code

// page-file-upload.component.ts

import { Component } from '@angular/core';
import { FileUploadService } from './file-upload.service'; // we will create this next!

  selector: 'page-file-upload',
  templateUrl: './page-file-upload.component.html',
  styleUrls: ['./page-file-upload.component.css']
export class PageFileUploadComponent {

  uploadedFiles = [];
  currentStatus: number;
  uploadFieldName = 'photos';

  readonly STATUS_INITIAL = 0;
  readonly STATUS_SAVING = 1;
  readonly STATUS_SUCCESS = 2;
  readonly STATUS_FAILED = 3;

  constructor(private _svc: FileUploadService) {
    this.reset(); // set initial state

  filesChange(fieldName: string, fileList: FileList) {
    // handle file changes
    const formData = new FormData();

    if (!fileList.length) return;

    // append the files to FormData
      .map(x => {
        formData.append(fieldName, fileList[x], fileList[x].name);

    // save it;

  reset() {
    this.currentStatus = this.STATUS_INITIAL;
    this.uploadedFiles = [];
    this.uploadError = null;

  save(formData: FormData) {
    // upload data to the server
    this.currentStatus = this.STATUS_SAVING;
      .delay(1500) // DEV ONLY: delay 1.5s to see the changes
      .subscribe(x => {
        this.uploadedFiles = [].concat(x);
        this.currentStatus = this.STATUS_SUCCESS;
      }, err => {
        this.uploadError = err;
        this.currentStatus = this.STATUS_FAILED;
  1. Later on, we will call the Hapi.js file upload API to upload images, the API accept a field call photos. That's our file input field name.
  2. We handle the file changes with the filesChange function. FileList is an object returned by the files property of the HTML element. It allow us to access the list of files selected with the element. Learn more [here]((
  3. We then create a new FormData, and append all our photos files to it. FormData interface provides a way to easily construct a set of key/value pairs representing form fields and their values. Learn more here.
  4. The save function will call our file upload service (hang on, we will create the service next!). We also set the status according to the result.

# File Upload Service

// file-upload.service.ts

import { Injectable } from '@angular/core';
import { Http, RequestOptionsArgs, Headers } from '@angular/http';

export class FileUploadService {

    baseUrl = 'http://localhost:3001'; // our local Hapi Js API

    constructor(private _http: Http) { }

    upload(formData) {
        const url = `${this.baseUrl}/photos/upload`;
        return, formData)
            .map(x => x.json())
            .map((x: any[]) => x
          // add a new field url to be used in UI later
                .map(item => Object
                    .assign({}, item, { url: `${this.baseUrl}/images/${}` }))
Nothing much, the code is pretty expressive itself. We upload the files, wait for the result, map it accordingly.
Now wire up your component and service to module, usually app.module.ts, and run it.

# Display Success and Failed Result

We can upload the files successfully now. However, there's no indication in UI. Let's update our HTML.
<!-- page-file-upload.component.html -->

  <div class="margin-20" *ngIf="currentStatus === STATUS_SUCCESS">
    <h2>Uploaded {{ uploadedFiles.length }} file(s) successfully.</h2>
      <a href="javascript:void(0)" (click)="reset()">Upload again</a>
    <ul class="list-unstyled">
      <li *ngFor="let item of uploadedFiles">
        <img [src]="item.url" class="img-responsive img-thumbnail" 

  <div class="margin-20" *ngIf="currentStatus === STATUS_FAILED">
    <h2>Uploaded failed.</h2>
      <a href="javascript:void(0)" (click)="reset()">Try again</a>
    <pre>{{ uploadError | json }}</pre>
  1. Display the uploaded image when upload successfully.
  2. Display the error message when upload failed.

# Fake the Upload in Front-end

If you are lazy to start the back-end application (Hapi, Express, etc) to handle file upload. Here is a fake service to replace the file upload service.
// file-upload.fake.service.ts

import { Injectable } from '@angular/core';
import { Observable } from 'rxjs/Rx';

export class FileUploadFakeService {

    upload(formData: any) {
        const photos: any[] = formData.getAll('photos');
        const promises = File) => this.getImage(x)
            .then(img => ({
                id: img,
                url: img
        return Observable.fromPromise(Promise.all(promises));

    private getImage(file: File) {
        return new Promise((resolve, reject) => {
            const fReader = new FileReader();
            const img = document.createElement('img');

            fReader.onload = () => {
                img.src = fReader.result;


    private getBase64Image(img) {
        const canvas = document.createElement('canvas');
        canvas.width = img.width;
        canvas.height = img.height;

        const ctx = canvas.getContext('2d');
        ctx.drawImage(img, 0, 0);

        const dataURL = canvas.toDataURL('image/png');

        return dataURL;
Came across this solution in this Stackoverflow post. Pretty useful. My online demo is using this service.
Basically, what the code do is read the source, draw it in canvas, and save it as data url with the canvas toDataURL function. Learn more about canvas here.
If you realize, our fake service has a same public interface as the real file upload service, both has upload function and return list of files. This is important for the next step, swap the real file upload service with the fake one.

# Swap the Real File Upload with the Fake Service

First you might think that to use the fake service, you need to register the fake service in module, and import it in our file upload component like how we do usually. However, there's a quicker way, with Angular dependency injection (DI). Let's look at our App module.
// app.module.ts

import { PageFileUploadComponent, FileUploadFakeService, 
  FileUploadService } from './file-upload';

  providers: [
    // FileUploadService, // normally we do this, comment it, we do the below instead
    { provide: FileUploadService, useClass: FileUploadFakeService }, // we can do this instead

export class AppModule { }
With this, you don't need to change your component code, stop your backend API, refresh the browser, you should see our app is still working, calling fake service instead.
In short, Providers: [FileUploadService] is the short form of Providers: [{ provide: FileUploadService, useClass: FileUploadService }]. Therefore, as long as we have another class with similar interface, we can swap it easily.
Angular DI is powerful. We'll leave that for another post.

Wednesday 3 May 2017

quantum computer and how does it work

In a world where we are relying increasingly on computing, to share our information and store our most precious data, the idea of living without computers might baffle most people.
The massive amount of processing power generated by computer manufacturers has not yet been able to quench our thirst for speed and computing capacity. But if we continue to follow the trend that has been in place since computers were introduced, by 2040 we will not have the capability to power all of the machines around the globe, according to a recent report by the Semiconductor Industry Association.

Will we ever have the amount of computing power we need or want? If, as Moore's Law states, the number of transistors on a microprocessor continues to double every 18 months, the year 2020 or 2030 will find the circuits on a microprocessor measured on an atomic scale. And the logical next step will be to create quantum computers, which will harness the power of atoms and molecules to perform memory and processing tasks.
Quantum computing is the area of study focused on developing computer technology based on the principles of quantum theory, which explains the nature and behavior of energy and matter on the quantum - atomic and subatomic level.
Quantum computing is still in the field of research and studies of theoretical computation systems that make direct use of the quantum - mechanism, such as superposition and entanglement, to perform operations on data. Development of a quantum computer, if practical, would mark a leap forward in computing capability far greater than that from the abacus to a modern day supercomputer, with performance gains in the billion-fold realm and beyond.
Quantum computers are different from binary digital electronic computers based on transistors. It follows the laws of quantum physics, which help to takes advantage of the strange ability of subatomic particles to exist in more than one state at any time. Due to the way the tiniest of particles behave, operations can be done much more quickly and use less energy than classical computers.
In classical computing, a bit is a single piece of information that can exist in two states – 1 or 0. Quantum computing uses quantum bits, or 'qubits' instead. These are quantum systems with two states. However, unlike a usual bit, they can store much more information than just 1 or 0, because they can exist in any superposition of these values.

Future of Quantum Computers

Last year, a team of Google and NASA scientists found a D-wave quantum computer was 100 million times faster than a conventional computer. But moving quantum computing to an industrial scale is difficult.

IBM recently announced its Q division is developing quantum computers that can be sold commercially within the coming years. Commercial quantum computer systems "with ~50 qubits" will be created "in the next few years," IBM claims. While researchers at Google, in Nature comment piece, say companies could start to make returns on elements of quantum computer technology within the next five years. 
But, quantum computers are still hard to manufacture because - scientists still have not found a simple way to control complex systems of qubits.