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  Hadoop or Spark: Which One is Better?

What is Hadoop? Hadoop is one of the widely used Apache-based frameworks for big data analysis. It allows distributed processing of large data set over the computer clusters. Its scalable feature leverages the power of one to thousands of system for computing and storage purpose. A complete Hadoop framework comprised of various modules such as: Hadoop Yet Another Resource Negotiator (YARN MapReduce (Distributed processing engine) Hadoop Distributed File System (HDFS) Hadoop Common Thes...

   COMPARISON,HADOOP,SPARK     2018-11-22 07:08:57

  A new SSL 3.0 vulnerability named POODLE is released

Today a new SSL v3 security vulnerability is released by Google and it affects all products which is using SSL v3 protocol as this vulnerability is introduced by a design flaw. Google revealed details of the design flaw on Tuesday, and dubbed it POODLE – short for Padding Oracle On Downgraded Legacy Encryption. It is a blunder within the blueprints of SSL 3.0 rather than a software bug, so it affects any product following the protocol – from Google Chrome and Mozilla Firefox to Micro...

   SSL v3, vulnerability, Google, POODLE     2014-10-15 04:48:59

  Create wireless hotspot on your smartphone

It's now very common that you may not get Internet connection in first few days when you move to a new place. And you may have some important things to handle or you may just want to connect to Internet and share with others your new place. If you have a smartphone which has enough mobile data package, then you are on the way to enjoy Internet. Today we will introduce how to create a wireless hotspot on your smartphone with Samsung Galaxy S3 i9300. Step 1 Go to Settings -> More Settings ->...

   Wireless hotspot, Smartphone, Samsung     2013-01-12 23:08:39

  Unknown system variable 'query_cache_size' in DbVisualizer while accessing MySQL

DbVisualizer is a very popular GUI application to view the data stored on a database. It supports various databases such as Oracle, MySQL etc. It relies on different database drivers to connect to the database server and access the data stored there.  In this post, we will try to solve one problem when accessing the latest MySQL database(8.0+) through DbVisualizer. MySQL database starting from 8.0 has lots of changes which may not be compatible with old version of software or libraries whic...

   MYSQL,MYSQL 8,DBVISUALIZER,QUERY_CACHE_SIZE     2018-06-30 03:48:17

  Using Java keytool programmatically

Java provides a command line tool to access and operate different keystore which store keys and certificates. This tool is named keytool and is located at \bin.  On command line, you can issue below command to generate a keystore named mytest.jks which contains a private key and certificate chain. keytool -genkeypair -alias mykey -keyalg RSA -sigalg SHA256withRSA -dname CN=Java -storetype JKS -keypass password -keystore mytest.jks -storepass password Sometimes, in testing purpose, w...

   JAVA,KEYTOOL     2016-01-09 06:28:07

  Ruby net-scp cannot scp multiple files with asterisk(*)

net-ssh/net-scp is a Ruby gem which can be used to scp files between different *nix machines. It's similar to how the *nix scp command. It can be used to scp a file or a directory. However, it seems it has some problem to scp multiple files using pattern *. For example, below script is supposed to download all files from remote directory to local directory: require 'net/scp' host = 'testmachine' login = 'testaccount' password = "testpassword" remote_path = '/tmp/remote...

   NET-SCP,RUBY,ASTERISK,MULTIPLE FILES     2016-10-20 03:00:13

  Traditional recursion vs Tail recursion

Recursion is a frequently adopted pattern for solving some sort of algorithm problems which need to divide and conquer a big issue and solve the smaller but the same issue first. For example, calculating fibonacci  accumulating sum and calculating factorials. In these kinds of issues, recursion is more straightforward than their loop counterpart. Furthermore, recursion may need less code and looks more concise. For example, let's calculate sum of a set of numbers starting with 0 and st...

   ALGORITHM,RECURSION,TAIL RECURSION,TRADITIONAL RECURSION     2016-09-23 23:54:09

  Get Facebook, Twitter and YouTube back

Facebook, Twitter and YouTube have become part of many people's daily network life. People hang around these sites to network with known and unknown friends, to know about the latest news and to relax with fancy video clips. But what will you feel if all of a sudden you cannot access them? Want to experience this? Go behind the GFW(Great Firewall) of China. Just a joke, but it's real. Huh, you are out of China? Don't worry. Change your DNS server to those located in China. I just experienced it,...

   DNS spoofing, GFW, YouTube, 37.61.54.158     2014-12-20 21:41:34

  Resolve stylesheet_link_tag fails to work in Ruby on Rails

When developing Ruby On Rails application, developers sometimes will see an unexpected behavior where the application cannot be loaded due to "TypeError: Object doesn't support this property or method" when invoking stylesheet_link_tag. The symptom looks like  And the Rails log will show something similar to below The error occurs because there is some problem finding the correct assets which are located in app/assets. To resolve the issue, you can following below steps. Add gem 'coffee-...

   RUBY ON RAILS,STYLESHEET_LINK_TAG,JAVASCRIPT_INCLUDE_TAG,TYPEERROR     2016-10-14 03:59:11

  Handle NXDomain error when resolving IP address in Ruby DNS resolver

In another post, we covered how to resolve SystemStackError when resolving IP address in Ruby. In this post, we would cover another common issue where a NXDomain error is returned when resolving an IP address. The NXDomain error means that the queried domain name does not exist in the DNS. In Ruby, DNS resolver library will use /etc/resolv.conf by default get the name servers to resolve the domain name. There are multiple DNS name servers can be specified in /etc/resolv.conf with below format. ...

   RUBY,RUBY ON RAILS,NETWORK,DNS,NXDOMAIN     2017-07-16 01:39:23

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