Techie Notes

Tuesday, April 23, 2013

Custom JSP tags

1) Make sure that the library for tags is in your classpath. servlet-api-2.3.jar supports it.
2) Create the tag class
Ex.
public class MyTag extends TagSupport
public class HelloTag extends SimpleTagSupport
3) Create the tag libray descripto file and put anywhere inside WEB-INF directory
Ex. WEB-INF/tld/myApp.tld

<taglib>
  <tlib-version>1.0</tlib-version>
  <jsp-version>2.0</jsp-version>
  <short-name>Example TLD</short-name>
  <tag>
    <name>Hello</name>
    <tag-class>com.tutorialspoint.HelloTag</tag-class>
    <body-content>empty</body-content>
  </tag>
</taglib>

4) Use the tag. You can also set uri in tld and use it as your uri in JSP page.

<%@ taglib prefix="ex" uri="WEB-INF/tld/myApp.tld"%>
<html>
  <head>
    <title>A sample custom tag</title>
  </head>
  <body>
    <ex:Hello message="This is custom tag" />
  </body>
</html>

Tuesday, April 2, 2013

Merging in SVN using Eclipse

Do a fresh checkout of the project where you are going to merge into. This is done to ensure that your target branch is up to date.
Right click the project and click Team -> Merge
In URL, browse on the source project
Click Ok
Resolve any conflicts

Thursday, February 7, 2013

JBoss Drools

JBoss/JBoss AS (JavaBeans Open Source Software Application Server)

- now has a new name WildFly
- is a J2EE platform for developing and deploying enterprise Java applications, Web applications and services, and portals

Drools/JBoss Rules

- a rule language
- case sensitive
- single line comments starts with # or //, multi-line comments are enclosed in /* and */

Rule file - file ending with .drl

jBPM

- is a flexible java Business Process Management (BPM) Suite
BPM makes the bridge between business analysts, developers and end users, by offering process management features and tools in a way that both business users and developers like it

Components of jBPM

core process engine - the only required component

history log
human task service

graphical editors

eclipse plugin
web-based designer

Guvnor respository - can store all business processes
jBPM console - web-based console for managinf business processes

http://docs.jboss.org/drools/release/5.2.0.Final/drools-expert-docs/html/index.html

Core

knowledge base
- used to look up the process definitions whenever necessary
- uses a knowledge builder to load processes from various resources (for example from the classpath, from file system or process repository), i.e.

KnowledgeBuilder kbuilder = KnowledgeBuilderFactory.newKnowledgeBuilder();
kbuilder.add(ResourceFactory.newClassPathResource("ruleflow.rf"), ResourceType.DRF);

- can be dynamically changed (so you can add or remove processes at runtime)
session
- instantiated from knowledge base and are used to execute processes and interact with the engine

Structure of a Rule File:

package package-name - must always be the first element
imports - optional, order does not matter
globals - optional, order does not matter, define global vars
functions - optional, order does not matter


function String hello(String name) {

    return "Hello "+name+"!";

}

queries - optional, order does not matter
rules - optional, order does not matter


rule "name"

    attributes

    when

        LHS

    then

        RHS

end

Common rule attributes:

salience - priority, higher salience values are given higher priority, default is 0, can be positive or negative
agenda-group - a group name, only rules in the agenda group that has acquired the focus are allowed to fire
activation-group - same as if else, only one will fire

Ref:
http://docs.jboss.org/jbpm/v5.1/userguide/

Monday, January 28, 2013

Ant buildfile

Each buildfile contains one project and at least one (default) target. Targets contain task elements.

Basic components/tags:
1) project - attributes: name, default, and basedir

2) target - attributes: name, depends, if, unless, descriptiondefault, and basedir

3) tasks - can be built-in or user defined
Common tasks: init, sets properties, prepare, creates directories, build, builds the system, package, creates jar file, install, installs an application to Tomcat or other engine, deploy, deploy a WAR engine, reload, update previously installed application engine, redeploy

4) properties - to reference, enclose in "${" and "}"
Some Built-in Properties: basedir, ant.file, ant.version, ant.project.name, ant.java.version

Tags:
...

Ref:
http://ant.apache.org/manual/using.html

Sunday, January 27, 2013

Windows and Unix common commands

Windows	Unix	Description
attrib		change(clear or set) the attribute of the file
cd	pwd	print current working directory
cd <dir>	cd <dir>	change directory
cls	clear	clear screen
cmd		Starts a new instance of the Windows command interpreter
copy	cp	copy cp /mySrc .
date, time	date	print current date and/or time
del	rm	delete
deltree	rm - r	recursively delete entire directory tree
dir	ls	list files and directories ls attributes: -a Include hidden fiels (beginning with .) -l long format -s sort by time modified -r reverse sort
doskey /h	history	print history
edit	vi etc.	create new file, show edit window common vi commands: /<text> - search forward n - next occurrence ?<text> - search backward n - previous occurrence :set number - show line number :q \| :quit \| :q! - quit
exit	exit Ctrl-D	exit
	find	finds files/folders or string in files Ex. dir c:\ /s /b \| find "CPU" - display the file names on drive C that contain the string "CPU" find . -name "foo*"
find	grep	search grep -n 'UnknownServiceException' ///server.log grep -rni "string" .* grep -E "a\|b" r = recursive i.e, search subdirectories within the current directory n = to print the line numbers to stdout i = case insensitive search .* = hidden files/directory -E = extended regex (i.e., may use \| for or)
help	man	help/manual displays all available commands & how to use them
ipconfig /all	ipconfig -a	print network details
mkdir	mkdir	create new folder/directory
move	mv	move file or folder
rmdir	rmdir	remove folder/directory
set	env	set environment variable
set Path	echo $PATH	print value of environment var PATH
start		starting/opening a command/program List of commands for Windows XP, Vista and Windows 7: http://ss64.com/nt/run.html Ex. subst notepad start /d "C:\Program Files (x86)\Notepad++" notepad++.exe -> start the executable and close the command prompt that called it
subst		substituting path subst R: D:\temp\temp
type	cat	display contents of a file, concatenate files or create a new file Ex. cat > 1.txt This is the first line. - creates a simple text file. ^D mrks the end of file. cat 1.txt - display contents of 1.txt cat 1.txt 2.txt > 3.txt - concatenate 1.txt and 2.txt ans save it in 3.txt
tree	find ., ls -R	print directory structure
	less	display the contents of a text file on console
	ln	make link Types: 1. Hard link (default) - Points to a file through inode number. If the original file's name is changed, hard link still points to same file. 2. Symbolic link (ln -s) - Points to a file through name. If the original file's name is changed, symbolic link still points to the original name and does not point anymore to the original file. If the original file's content is changed, symbolic link still points to the same file. ln -s myFolder myShortcut - create ln -sfn myFolder2 myShortcut - update -f = force -n = treat LINK_NAME as a normal file if it is a symbolic link to a directory, else LINK_NAME will be treated as symbolic link and will not effectively remove link to previous target and point to new target
	printenv	print environment variables
	tar	archive/extract tar -xvf sample.tar.gz

PATH

Windows	Unix	Description
\	/	Directory separator, e.g. C:\user\docs\sample.txt
/	-	Switch, e.g. dir /w
[drive letter:]\ or \\[server name]\[volume]\	/	Root directory
.	.	Current directory
..	..	Parent directory
	~	Home directory - $HOME var in UNIX, which usually is /home/username
C:\user\docs\sample.txt docs\sample.txt A:pic.jpg \\server01\user\docs\sample.txt	//home/user/docs/Letter.txt . /inthisdir ../../greatgrandparent ~/.rcinfotd>	Sample paths

Source:
https://en.wikipedia.org/wiki/Path_(computing)

Sunday, January 13, 2013

Software Testing

Testing Levels

Unit testing

done in local/DEV
testing fixes individually

Integration testing

done in SIT
testing integrated modules
deals with integration of a process in the system, not the integration of the whole system

System testing

done in SIT
testing the system as a whole
Types of system testing:

Usability testing – this is how well the user can access the different features in the system and how easy it is to use.
GUI software testing – this is to check if graphically that the program looks how was intended and the GUI works as intended.
Security testing – this would be to check if important information is secure and if there are certain access restriction that they work.
Accessibility – how easy is it for various users including users with disability to use the system.
Reliability testing – to check that the system works for long period of time and does not constantly crash.

User acceptance testing

done in UAT
obtain confirmation that a system meets mutually agreed-upon requirements

Wednesday, October 3, 2012

Outline: Warren Buffett's Management Secrets

by Mary Buffett and David Clark

Step 1. Pick the right business to work for (business that offers greatest career opportunities)

Chapter 1. how to find companies that offer greatest career opportunities (w/ durable competitive advantage)

have products that:
- never really change
- easy to sell
- own a piece of consumer's mind

come in 3 basic business models:
- sell unique product, e.g. Coca Cola, Hershey
- sell unique service, sell what people need
- low cost buyer and seller of product/service that the public is consistently in need of - offer low cost through high volum, e.g. Walmart, Costco, Burlington

Chapter 2. quick test for identifying the best company to work for

- per share earnings test (10 year period) - consistent and has upward trend
- debt test - long term debt must be low, debt load should be < 5*net earnings
- gross margin test - must be higher
gross profit = revenue - cost of good sold
gross margin = gross profit/revenue

Step 2. Delegate

Chapter 3. rules for delegating authority

- every business culture is unique
- leave managers alone - let them continue to think their business as their own
- managers must have a GREAT deal of INTEGRITY

Step 3. Find the right manager for the job

Chapter 4. where to start search for manager

- change manager only when necessary
- promote from within if possible
- look for talent w/ proven talent record

Chapter 5. victor or victim

- must have an internal locus of control
- victor = with internal locus of control - in control of themselves, take responsibility for their failures
- victim = with external locus of control - don't believe that they have power to solve their problems

Chapter 6. work at a job you like

- do what you love/love what you do, must not be driven by money

Chapter 7. put a winning sales team together

- find people who believe in the product

Chapter 8. obsession

- sd

Monday, September 3, 2012

Useful Maven Commands

mvn --version - displays the Maven version in use
mvn dependency:tree - displays the dependency tree for this project
mvn eclipse:eclipse - creates/updates Java eclipse project settings (.project, .classpath, .setting/org.eclipse.jdt.core.prefs, & other config files)
mvn eclipse:clean - cleans/removes Java eclipse project settings (.project, .classpath, .setting/org.eclipse.jdt.core.prefs, & other config files)

Monday, June 18, 2012

Useful DB2 Queries

ALL TABLES:
select * from sysibm.systables

TABLE DESCRIPTION:
select * from sysibm.syscolumns where tbname = 'tableName'
- NOT VERY RELIABLE, SOME COLs MIGHT BE MISSING

or

select colname, typename, length, scale from syscat.columns
where tabschema = 'schemaName' and tabname = 'tableName'
- NOT VERY RELIABLE, SOME COLs MIGHT BE MISSING

or

describe table tableName - DOES NOT WORK :(

Note: Use SYSCAT views rather than the SYSIBM tables. Reason being is that from release to release the tables are being revised while DB2 development tries hard to keep the SYSCAT view signatures compatible. For this reason SYSCAT is being described in the SQL Reference while SYSIBM is not.

GET CURRENT DATE/TIME:
select current date from sysibm.sysdummy1
select current time from sysibm.sysdummy1
select current timestamp from sysibm.sysdummy1

Note: sysibm.sysdummy1 table is a special in-memory table that can be used to discover the value of DB2 registers

Sources:
http://www.databaseteam.org/9-db2/b4ac3f33bec9fb23.htm#.UfdJQ41OS6M
http://www.ibm.com/developerworks/data/library/techarticle/0211yip/0211yip3.html

Tuesday, May 22, 2012

Database Normalization

First Normal Form (1NF)
- no duplicate columns, e.g. teacher, student1, student2, student3
- no non-atomic columns, e.g. teacher, students
- rows must be have unique identifier (primary key), e.g. teacher, studentID, studentName

Second Normal Form (2NF)
- satisfied 1NF
use foreign key (move subset of data/column that apply to multiple rows of a table to another table and connect them through the foreign key)
e.g.
studentID, studentName, courseID, courseName to
studentID, studentName, courseID and courseID, courseName

Third Normal Form (3NF)
- 2NF
- remove columns that are not dependent upon primary key
e.g.

Boyce-Codd Normal Form (BCNF or 3.5NF)

Fourth Normal Form

Sunday, May 20, 2012

Apache log4j

DEBUG < INFO < WARN < ERROR < FATAL

Tuesday, May 15, 2012

HTML

Complete list of HTML tags: http://www.w3schools.com/tags/default.asp

- HTML stands for Hyper Text Markup Language
- HTML is not a programming language, it is a markup language
- Practically speaking, there is no difference between the htm and html extensions
- In XHTML, all elements must be closed. Adding a slash inside the start tag, like
, is the proper way of closing empty elements in XHTML (and XML)
- HTML tags, attribute names and attribute values are not case sensitive but World Wide Web Consortium (W3C) recommends lowercase in HTML 4, and demands lowercase tags in XHTML. Newer versions of (X)HTML will demand lowercase attributes
- In XHTML, XML, elements with no end tag (closing tag) are not allowed
- attribute id vs name: id must be unique and is used as an identifier of an HTML element while name is used for form elements and form elements can share the same name
- HTML comment sample:

 <!-- This is a comment -->

- The <center>, <font>, <basefont>, <s>, <strike> and <u> tags and align, bgcolor and color attributes are deprecated in HTML 4, and removed from HTML5. Style sheets (CSS) should be used to define the layout and display properties for many HTML element
- Always add a trailing slash to subfolder references. If you link like this: href="http://www.w3schools.com/html", you will generate two requests to the server, the server will first add a slash to the address, and then create a new request like this: href="http://www.w3schools.com/html/"
- HTML frames are obsolete in HTML5. Cons: http://webdesign.about.com/od/framesprosandcons/a/aaframesyuck_2.htm
- The doctype declaration refers to a Document Type Definition (DTD). The DTD specifies the rules for the markup language, so that the browsers render the content correctly.

 <!-- This is a comment -->

Reference: http://www.w3schools.com

Wednesday, May 9, 2012

How to create Sublabels / Hierarchical Labels in Blogspot

I always wanted my label section to look like the archive section where labels can have hierarchy and the number of posts is displayed beside each label. I learned how to create the hierarchical tree from this blog but the nodes have to be added one by one and the number of posts per label are not displayed so I tweaked it a little to suit my needs. Here are the steps:

Add the Labels gadget if is not yet added
From your dashboard, click Layout -> Add a Gadget and select Labels
Add an HTML gadget. This is where you will create your hierarchical labels.
From your dashboard, click Layout -> Add a Gadget and select HTML/Javascript
Ensure that the Labels gadget comes first before the HTML gadget in your layout.
From your dashboard, click Layout and arrange your gadgets by dragging them to the desired location so that the Labels gadget is on top or comes first before the HTML gadget

Update the Template

Add the dtree javascript.
From your dashboard, click Template -> Edit HTML -> Proceed and check Expand Widget Templates. Copy and paste this code

<link href='https://sites.google.com/site/efekefek/file-js/dtree.css' rel='StyleSheet' type='text/css'/>
<script src='https://sites.google.com/site/efekefek/file-js/createdtree.js' type='text/javascript'/>

after this tag

<b:skin><![CDATA[/*

Remove the Label widget content
Find the Label widget code. It looks like this

<b:widget id='Label1' locked='false' title='Labels' type='Label'>
<b:includable id='main'>
    
 ...  

</b:includable>
</b:widget>

Replace the code inside <b:includable id='main'> and </b:includable> with this code

<script type='text/javascript'>
  var labelCountMap = {};
  <b:loop values='data:labels' var='label'>
     labelCountMap ["<data:label.name/>"] = "<data:label.count/>";
   </b:loop>
</script>

Save template

Prepare the code of the Hierarchical Labels
Copy the code below and replace the data with your own Labels. The data is in format

parentLabel: { subLabels }

The subLabels are comma separated. If the parentLabel doesn't have subLabels, replace it with {}.

<div class="dtree">
<p><a href="javascript: d.openAll();">open all</a> | <a href="javascript: d.closeAll();">close all</a></p>
<script type="text/javascript">
<!--
function isEmpty(obj) {
    for(var prop in obj) {
        if(obj.hasOwnProperty(prop))
            return false;
    }
    return true;
}

function addMap(d, startingNode, parentNode, map) {
 for (var key in map) {
  if (isEmpty(map[key])) {
   d.add(startingNode++,parentNode,key+' ('+labelCountMap[key]+')','/search/label/'+key);
  } else {
   d.add(startingNode++,parentNode,key+' ('+labelCountMap[key]+')','/search/label/'+key);
   startingNode = addMap(d, startingNode, startingNode-1, map[key]);
  }
  
 }
 return startingNode; 
}

var data = {
 'Label 1' : {
  'Label 1.1' : {},
  'Label 1.2' : {
   'Label 1.2.1' : {}
  }, 
  'Label 1.3' : {}
 }, 
 'Label 2' : {
  'Label 2.1' : {}, 
  'Label 2.2' : {}
 }, 
 'Label 3' : {}, 
 'Label 4' : {}};

d = new dTree('d');
d.config.useLines = true;
d.config.useIcons = false;
d.config.inOrder = true;

d.add(0,-1,'');   
addMap(d, 1, 0, data);

document.write(d);
//-->
</script>
</div>

Paste the code in the HTML widget
From your dashboard, click Layout and Edit the HTML widget. Paste the code inside Content and Save