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  Output a file with HTTP range header in PHP

When downloading a large file, we may encounter some network issues which causes download termination and only part of the file is downloaded. When the network connection resumes next time, we may need to redownload the file again from the beginning. In order to save bandwidth, http provides a Range parameter in its header which can control the file transfer flow. With the range parameter in the header, we can resume the download from where we stop. Here is a piece of PHP code snippet which uses...

   PHP, range,http, file transfer     2013-01-09 05:55:05

  JavaScript tips both novice and veteran developers can benefit from

In this post, we will share some less known but powerful JavaScript tips which can benefit both novice and veteran JavaScript developers. 1. Truncate array with array length We all know that object are passed by reference in JavaScript, but we may be bitten by this rule. Please check below example: var arr1 = arr2 = [1, 2, 3]; //Change arr1 arr1 = []; // arr2 will still be [1,2,3] arr1 and arr2 point to the same array [1,2,3] initially, later when arr1 repoints to [], the reference to arr2 is n...

   JavaScript,Array,push     2013-08-21 04:09:10

  How to Choose the Right Ruby on Rails Hosting Platform

Over the last decade, Ruby on Rails has become an increasingly popular framework for web-based apps. At its beginnings, hosting Rails was a real challenge and required a fair amount of relevant know-how. Nowadays, there are dozens of hosting platforms that provide cheap and accessible services for building and deploying Rails apps. In general, the choice of hosting should be based on your requirements and technical skills – some platforms are much more difficult to handle than others. Here...

   ruby on rails, ruby hosting     2015-01-30 06:27:47

  Using JavaScript to operate clipboard

Browsers allow JavaScript to read and write data on clipboard. Generally script should not modify user's clipboard to avoid impacting user expectation, but there are cases where this can indeed bring convenience to users. For example, for some code snippet, user can copy it to clipboard with one click instead of select and copy manually. There are three options for clipboard operation provided in JavaScript/browser: document.execCommand() Asynchronous Clipboard API copy and paste events This p...

   JAVASCRIPT,CLIPBOARD,NAVIGATOR.CLIPBOARD     2021-01-23 23:23:34

  Signature sign/verification demo in Java

Digital signature is commonly used in areas where data authentication and integrity are required. It is extremely important to have signature while transferring sensitive data from one peer to other peers through network since there might be malicious applications or man-in-the-middle attacks which may alter the data along the way. Java provides some APIs to generate and verify digital signature. One important class is Signature.  When generating the signature, a private key needs to be pa...

   SECURITY,JAVA,SIGNATURE     2015-11-21 09:48:12

  A Python assignment trap

Python has no assignment, it only has reference. Assume, we have following code snippet: >>> values = [0, 1, 2] >>> values[1] = values >>> values [0, [...], 2] Why the result is not [0, [0, 1, 2], 2], instead it goes into an infinite loop? To understand this, we need to understand some basics about Python. Python has no variables, it only has labels. When we run: values = [0, 1, 2] Python will first create a list object [0,1,2], then it labels it as values. If we later...

   Python,Assignment,Trap,Shallow copy     2013-07-19 22:08:36

  Why can System.out.println be used to exit while loop

Let's first take a look at one simple Java thread code snippet which is supposed to exit the while loop after the first loop run. public class StopThread { private static boolean stopRequested; public static void main(String[] args) throws InterruptedException { Thread backgroundThread = new Thread(new Runnable() { @Override public void run() { int i = 0; while (!stopRequested) { i++; } } }); backgroundThread.start(); TimeUnit.SECONDS.sleep(1); stopRequested = true; } } But the tr...

   JAVA,THREAD,VOLATILE     2018-12-21 19:25:54

  Generate certificate in Java -- Self signed certificate

This is the first post in this series which I will show you how to generate SSL certificate in Java programmatically. Certificates are frequently used in SSL communication which requires the authentication of server to client. This is to make the client to trust that the server is actually the one it claims. Certificates are really important on the Internet. All HTTPS communications on the Internet need the server side to present their certificates signed by trusted CAs. The basic flow of a requ...

   Java,Certificate,X509     2014-07-30 07:42:18

  JavaScript interview questions

This post will cover the JavaScript questions I have encountered and have seen during my programming career. They will mainly focus on vanilla JavaScript though there are lots of excellent frameworks out there and many people are using them in their daily work. this keyword this keyword is an very important but easy to confuse concept in JavaScript since it is always referring to the calling object of the function. 1. What will be the output of below code snippet? function User(name) { this....

   JAVASCRIPT,ALGORITHM,THIS,CLOSURE     2019-03-09 07:05:46

  Different types of keystore in Java -- PKCS11

PKCS11 keystore is designed for hardware storage modules（HSM）. It's an interface to talk to the HSMs. It doesn't actually store any keys but provide a set of classes to communicate with the underlying HSM. The actual keys and certificates are stored on the HSMs. The reason for storing the keys and materials is to ensure security and efficiency. Since the keys are on the HSMs, they are safe to be stolen. All encryption/decryption operations are performed on the HSMs as well, this incre...

   PKCS11,keystore,HSM,Java     2015-01-08 00:39:12

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