ThreadLocal and Inheritable ThreadLocal

I am not going to share any new concept or library of java. My topic of this post related to ThreadLocal that is with us since JDK version 1.2 but after discussion with many developers with in my circle I came to know that many developer doesn't know it feature and functionality.

Thread Local storage is just like class that can store/return object with in thread scope. Just like application context, session or request scope with in servlet.

Thread-local storage (TLS) is a computer programming method that uses static or global memory local to a thread [wikipedia].

ThreadLocal instances are typically private static fields in classes that usually maintain thread state 

This class is very useful if you want to share common objects into different applications layers like users credentials, connection objects etc. I usually use this class after wrapping it in my ThreadContext class. Following are the code of my ThreadContext class. 

To save my common object with in thread I usually call it's static put method and when I need to use that saved object I call it's static object.  

D3Js Basic Video Tutorials

I found excellent D3JS video tutorial on youtube which explains basic in detail. The instructor describes all basic functionality provided by D3JS library with some practical examples. If you have an idea about Javascript and DOM then you can skip his first lecture.

Topics of D3JS Tutorials 

1. Introduction Part 1 
2. Select and Append functions Part 2. 
3. Basic SVG shapes Part 3.
4. Visualizing data Part 4 .
5. Scales function Part 5. 
6. Groups and axes Part 6. 
7. Enter, Update, Exit Part 7.
8. Transitions Part 8. 
9. Working With Arrays Part 9. 
10. Loading External Data Part 10. 
11. Paths Element Part 11.
12. Arcs Part 12.
13. The Pie Layout Part 13. 
14. The Tree Layout (1/2) Part 14. 
15. The Tree Layout (2/2) Part 15. 
16. Cluster, Pack & Bubble layouts Part 16. 
17. The Histogram Layout (1/2) Part 17. 
18. The Histogram Layout (2/2). 
19. The Treemap Layout Part 19. 
20. Maps in D3 Part 20. 

Here is playlist

SQL Joins through Visual illustration

http://www.codeproject.com/Articles/33052/Visual-Representation-of-SQL-Joins

D3Js Base Charting libraries

I found very good link in which some one listed all available d3js base charting libraries. Below are details

• NVD3 (http://nvd3.org/)
  • We used nvd3 in our project. If we have small data set it will work fine but in case large data set it starts hanging. 
• dimple (http://dimplejs.org/)
  •  Simple API to create charts
• C3.js (http://c3js.org/)
  • Highly customizable charting API and rich set of charts.
• xCharts (http://tenxer.github.io/xcharts/)
  • Limited sets of charts with customization options
• Rickshaw (http://code.shutterstock.com/rickshaw/)
• Limited sets of charts with customization options

Reference : https://gist.github.com/eabait/9916975

D3JS Drawing library & Gauge Chart

Today I was exploring different kind charting libraries to develop gauge chart in JavaScript. I explored the following charting libraries and finally developed gauge chart using d3js. we can develop extremely complicated graphs and charts using  d3js because it is drawing library and the good thing is that it will renders it's results in Scalable Vector Graphics (SVG).
The Javascript  libraries I explored for gauge charts are :

• Jqplot Provide simple meter in non attractive manner
• Flot  Better the Jqplot but but still less professional 
• Google Chart Professional output and it is also generating cross browser compatible HTML/SVG chart like d3js
• Fusion Chart(Commercial) professional output but not free

You can find below chart example from my github account. I took and extend example from following example https://gist.github.com/tomerd/1499279

Verified Certificate after Completed Full Course

Below in my verified certificate, I got this after completed full course including exercises , final project and  exit interview in which Udacity asked question about Hadoop & MapReduce and my final project.