Today's Question:  What does your personal desk look like?        GIVE A SHOUT

SEARCH KEYWORD -- NULL

  A HTTPS client and HTTPS server demo in Java

In this post, I will create a HTTPS server and HTTPS client demo which can establish HTTPS communication between a server and a client using Java. This should be very useful when we want to test our understanding about SSL communication. We will use both a detailed SSL client and a simple HttpsURLConnection as the HTTPS client. Before creating the actual HTTPS server and HTTPS client, we first need to generate the keystore and truststore to be used by the server and client. To generate the keyst...

   SSL,HTTPS,JAVA,DEMO     2015-10-23 09:04:36

  Shell script common interview questions

Shell script is frequently used when monitoring system status on Linux. It's not an easy task to write shell script but it's a very important skill for developers and system administrators to ease work and automate common tasks. This post will share some common interview questions about shell script. 1. Get random characters(8 characters) Method 1 # echo $RANDOM |md5sum |cut -c 1-8 471b94f2 Method 2 # openssl rand -base64 4 vg3BEg== Method 3 # cat /proc/sys/kernel/random/uuid |cut -c 1-8 ed...

   LINUX,INTERVIEW,SHELL SCRIPT     2018-09-28 10:46:00

  A String is not an Error

I decided to write a little article to discourage an unfortunately common pattern in Node.JS modules (and browser JavaScript, to a lesser extent) that can boil down to these two examples: // A:function myFunction () {  if (somethingWrong) {    throw 'This is my error'  }  return allGood;} and // B: async Node.JS-style callback with signature `fn(err, …)`function myFunction (callback) {  doSomethingAsync(function () {    // …    if (...

   JavaScript,Node.js,String,Error object     2011-12-23 08:00:32

  Select top 3 values from each group in a table with SQL

Yesterday, my friend Liu Bing asked me a question about how to select top 3 values for each person in a database table using SQL. I think this question is interesting and it deserves some thoughts. Here I record down how to solve this issue. Assume we have a table which has two columns, one column contains the names of some people and the other column contains some values related to each person. One person can have more than one value. Each value has a numeric type. The question is we want to se...

   SQL,Correlated query,top 3     2013-05-23 03:21:25

  Different types of keystore in Java -- JKS

JKS is Java Keystore, a proprietary keystore type designed for Java. It can be used to store private keys and certificates used for SSL communication, it cannot store secret keys however. The keytool shipped with JDKs cannot extract private keys stored on JKS. This type of keystore usually has an extension of jks. Next we will show how to operate the JKS keystore with pure Java code. Create JKS keystore The simplest method to create a JKS keystore to create an empty keystore. We can first get an...

   DEMO,EXAMPLE,KEYSTORE,JKS     2014-09-05 20:21:51

  The ugliest C feature:

<tgmath.h> is a header provided by the standard C library, introduced in C99 to allow easier porting of Fortran numerical software to C. Fortran, unlike C, provides “intrinsic functions”, which are a part of the language and behave more like operators. While ordinary (“external”) functions behave similarly to C functions with respect to types (the types of arguments and parameters must match and the restult type is fixed), intrinsic functions accept arguments of...

   C,,Fortran,Intrinsic functions,C99,Ugly     2011-12-26 08:33:27

  A trick of building multithreaded application on Solaris

Firstly, Let’s see a simple multithreaded application: #include <stdio.h> #include <pthread.h> #include <errno.h> void *thread1_func(void *p_arg) { errno = 0; sleep(3); errno = 1; printf("%s exit, errno is %d\n", (char*)p_arg, errno); } void *thread2_func(void *p_arg) { errno = 0; sleep(5); printf("%s exit, errno is %d\n", (char*)p_arg, errno); } int main(void) { pthread_t t1, t2; ...

   C, Solaris     2014-10-14 02:59:40

  Different types of keystore in Java -- BKS

BKS is a keystore format provided by the popular third party Java cryptographic library provider -- BouncyCastle. It is a keystore similar to the JKS provided by Oracle JDK.  Before starting to use BKS, the BouncyCastle provider has to be downloaded and installed. To download the provider, please go to BouncyCastle download page. The provider can be installed by adding an entry in the java.security file. security.provider.N=org.bouncycastle.jce.provider.BouncyCastleProvider N means the pr...

   JAVA,KEYSTORE,BOUNCYCASTLE,BKS     2016-07-03 03:00:18

  10 design flaws of JavaScript

JavaScript's design took only ten days. Moreover, the designer didn't want to design it initially, he just wanted to complete the task assigned by company. It is now a very powerful client side programming language used in almost all the websites. It's an excellent language, but it also has some flaws. 1. Not suitable for large projects JavaScript doesn't have namespace, it's hard to be modular, there is no standard for putting codes in multiple source files. It allows defining functions with th...

   JavaScript, Design flaw, Object     2012-11-29 11:39:35

  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

RECENT