Read a variable defined on the config file from a controller in a grail application

Let's say, you have the config.groovy file as follow.


...........
..........

environments {
production {
myVariable1="I am variable1 on RPOD"
myVariable1="I am variable1 on RPOD"
}



development {
myVariable1="I am variable1 on DEV"
myVariable1="I am variable1 on RPOD"
}

log4j {
appender.stdout = "org.apache.log4j.ConsoleAppender"
.........
........

Now the above varaible can be easily access through any of the controller as follow.


def config = ConfigurationHolder.config
def myVaraible1 = config.myVaraible1
def myVaraible2 = config.myVaraible2


Reading the status code of HTTP Request !

When you make an HTTP request to any server url throuh your client software, lets say IE, HTTP Status codes are returned by the server to the client software to determine the outcome of your request. There are five different classes of status code range. They are
Status codes 100-101
Status codes 200-206
Status codes 300-307
Status codes 400-417
Status codes 500-505

Following is a simple program written in groovy that checks and returns the status code of any url.

import java.net.URL;
def url
def message =""
boolean fail=true
def urlString="http://192.168.0.1/test/test.html"
println checkURL(urlString)

def checkURL(urlString){
int status_code
def tempmessage=""
URL URLserver = new URL("urlString");
try{
URLConnection connection = (HttpURLConnection)URLserver.openConnection();

status_code = connection.getResponseCode();


switch (status_code)
{
case 200:
tempmessage=" Connection Successful"
break;
case 401:
tempmessage="UnAuthorised"
break;
case 405 :
tempmessage= " Resource Not Found"
break;
case 408:
tempmessage="Request Time-out"
break;
case 500:
tempmessage="Internal Server Error"
break;
case 502:
tempmessage="Bad Gateway"
break;
case 503:
tempmessage="Service Temporarily Unavailable"
break;
default :
tempmessage= connection.getResponseMessage()
break;

}
}
catch (Exception exc){
tempmessage=exc

}

return "\n "+urlString+" :"+status_code+":"+tempmessage;

}




Visit http://www.w3.org/Protocols/HTTP/HTRESP.html for detail about the status codes.

Problems with Hotmail login

Hotmail has been going under the planned maintenance on its servers, So you might face some problem accessing your hotmail. Some of the problems that I am facing are like
1. Asking to enter password for multiple times
2. When i type in the address http:// hotmail.com in the address bar and enter than I get a message “The requested URL could not be retrieved”. Sometimes it loads the page but once I enter the password and username it throws the message “The requested URL could not be retrieved”, i.e. the connection timed out.
3. Some time I am able to log in but I get the same problem while sending or opening a message.
Solution:
Following are some of the solutions recommended by Microsoft,.
1. http://windowslivehelp.com/solutions/servicemgt/archive/2008/12/26/what-to-do-if-you-can-t-sign-into-windows-live-hotmail.aspx
2. http://windowslivehelp.com/solutions/accounts/archive/2009/03/03/How-to-optimize-Internet-Explorer-browser.aspx
3. http://windowslivehelp.com/solutions/servicemgt/archive/2008/08/22/how-to-determine-which-server-you-are-on.aspx

Microsoft to replace its live search engine with a new decision based engine “ Bing”

In order to compete with the giant search engine, Google, Microsoft has unveiled its new search engine, Bing. On May 28, 2009, Microsoft CEO Steve Ballmer has announced the new incarnation of live search as Bing, formerly code-named "Kumo". Bing is fully available from June 3, 09.
Microsoft has claimed that Bing is not only the search engine but a Decision Engine, designed to empower people to gain insight and knowledge from the Web, moving more quickly to important decisions.
“Today, search engines do a decent job of helping people navigate the Web and find information, but they don’t do a very good job of enabling people to use the information they find,” said Steve Ballmer, Microsoft CEO. “When we set out to build Bing, we grounded ourselves in a deep understanding of how people really want to use the Web. Bing is an important first step forward in our long-term effort to deliver innovations in search that enable people to find information quickly and use the information they’ve found to accomplish tasks and make smart decisions.”

Microsoft has aimed to gun down Google with Bing. Microsoft has already announced an $80 to $100 Million ad campaign for Bing. Google has spent about $25 million on all its advertising last year with $11.6 million for recruiting.
As show in the graph Microsoft search market share has been lowering down with just an 8.2% share of the market for core search compared to 64.2% for Google and 20.4% for Yahoo. Microsoft has been struggling to for improving its search advertisement revenue. Last year only Microsoft has offered more than $47 billion dollar bid. They might come up with another Microsoft-yahoo search deal by mid July.
Good luck to the Microsoft for the new product!

Read Environment Variables with Groovy

Environment variables can be easily accessed with Groovy with getenv() method as shown below.


def env = System.getenv()
//Print all the environment variables.

env.each{
println it
}
// You can also access the specific variable, say 'username', as show below
String user= env['USERNAME']



Spring’s JDBC Template Set Up for a Grail Application

To take an advantage of the Spring JDBC Template for any Grail application, the first thing you need to do, is to define the DataSource bean in resources.groovy , Don’t forget to have the jdbc driver(.jar) corresponding to your backend database server under the lib folder of your grail application.

For example ,resources.groovy is shown as below,

import org.springframework.jdbc.core.JdbcTemplate
import org.apache.commons.dbcp.BasicDataSource




beans = {
myDataSource(BasicDataSource) {
driverClassName = "oracle.jdbc.OracleDriver"
url ="jdbc:oracle:thin:@ . . . . . “
username = "myUser"
password = "myPass"
}
jdbcTemplate(JdbcTemplate)
{
dataSource=myDataSource
}

}



If you have used MS SQL server as your back end database, the driver class name and the url format is as follow.

myDataSource(BasicDataSource) {
driverClassName = "com.microsoft.jdbc.sqlserver.SQLServerDriver"
url = "jdbc:microsoft:sqlserver://myDataBaseServerURL"
}

Similarly for MYSQL database server, the driver class name and the url format could be as follows :

dataSource {
driverClassName = "com.mysql.jdbc.Driver"
url = "jdbc:mysql:// myDataBaseServerURL "
username = "myUser"
password = "myPass"
}

Once its set up you can simply make a query as follows
myResult = jdbcTemplate.queryForList (myQuery)

where myQuery is the query that needs to be execute on the remoteDatabase.

Generate Random Alphanumeric Random String of N Characters with Groovy or Java

I was googling for a Alpha-numeric Random String generation. I come up with two solution. One option is to generate Random Alphanumeric Strings with RandomStringUtils available on Apache Common . The following section of code is borrowed from java2s.com


import org.apache.commons.lang.RandomStringUtils;
public class RandomStringUtilsTrial {
public static void main(String[] args) {

//Random 8 chars string where letters are enabled while numbers are not.
System.out.print("8 char string using letters but no numbers >>>");
System.out.println(RandomStringUtils.random(8, true, false));

}
}


Other Option can be using the Java Uitil class Random as shown below. You don’t have to worry about Apache Common API. The following code section (written for Groovy) generates 100 '32 characters' long Alphanumeric Random string.



private static String validChars ="ABCDEFGHIJKLMNOPQRSTUVWXYZ1234567890_"
private int IDlength=32
int maxIndex = validChars.length()
for(i in 0..99)
{ String resultID = ""
java.util.Random rnd = new java.util.Random(System.currentTimeMillis()*(new java.util.Random().nextInt()))
for ( i in 0..IDlength ) {
int rndPos = Math.abs(rnd.nextInt() % maxIndex);
resultID += validChars.charAt(rndPos)
number=resultID
}

println resultID
}



Good luck !

cURL , A command line tool with URL Support !

One of my co-worker introduced a tool named cURL to me today. It a quite handy command line tool for transferring files with URL Syntax supporting most of the interner protocols like FTP, FTPS, HTTP, HTTPS, SCP, SFTP, TFTP, TELNET, DICT, LDAP, LDAPS and FILE. curl supports SSL certificates, HTTP POST, HTTP PUT, proxy tunneling , HTTP form based upload, proxies, cookies, user+password authentication (Basic, Digest, NTLM, Negotiate, Kerberos and many more)

You can download cURL from http://curl.haxx.se/ . It’s a free and open software tools.

For example curl http://nepalnews.com : return a html version of your web page in your console window. Its detail tutorial and example can be found at http://curl.haxx.se/docs/httpscripting.html

I have use curl on the following
curl -X POST -H 'Content-type: text/xml' -d @ http://myserver.com/process.gsp < firstfocus.xml

Here I am sending an xml file, firstfocus.xml, to the server myserver.com . process.gsp do calls the controller which helps in the business logic at the back end and return the result on my console window. It’s a pretty good tool for testing and development environment.
Thanks to Joshua for letting me know about this tool and its usage.

Free Java Technology Cources!

Dear Readers,
If you are interested with free online courses on java technologies, http://www.javapassion.com/ could be a good platform for you. Shan Shin teaches the courses. Sang Shin is presently working for Sun Microsystems as a Technology architect, consultant, and evangelist. After a successful completion of any courses you are awarded with the Certificate from java passion. I suggest you all to register for at least one source at a time. Detail about the schedule and courses can be seen at the course home page. Currently he is offering the following courses and all are totally free.

• Java Programming (with Passion!)
  
• Performance, Debugging, Testing, Monitoring, and Management (with Passion!)
  
• Java EE Programming (with Passion!)
  
• Ajax Programming (with Passion!)
  
• Web Services Programming (with Passion!)
  
• Sun Java System Identity Manager (with Passion!)
  
• Java FX Programming (with Passion!)
  
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How to read a Java Session Back bean of a JSF page from JSP pages

In this section I am describing about accessing a JSF back bean from a JSP page.
Lets us take an example of a java back bean ServerInfo for a JSF page

// File Name : ServerInfo.java
package thomson.com;
public class ServerInfo {
String server;
String environment;

public String getServer() {
return server;
}

public void setServer(String server) {
this.server = server;
}
}

Bean is defined on faces-config.xml as following

<navigation-rule>
<from-view-id>/index.jsp</from-view-id>
<navigation-case>
<to-view-id>/process.jsp</to-view-id>
</navigation-case>
</navigation-rule>
<managed-bean>
<managed-bean-name>ServerInfoBean</managed-bean-name>
<managed-bean-class>thomson.com.ServerInfo</managed-bean-class>
<managed-bean-scope>session</managed-bean-scope>
</managed-bean>

Now lets take an example of JSF page section that sets up the java bean ServerInfoBean from the input text of the form as shown below

//File name: index.jsp
<f:view>
<h:form id="serverForm">
<h:outputLabel for="serverName">
<h:outputText value="Enter the Server Name"/>
</h:outputLabel>
<h:inputText id="serverName" value="#{ServerInfoBean.server}" required="true"/>
<h:message for="serverName"/>
<br>
<h:outputLabel for="environment">
<h:outputText value="Select Environment"/>
</h:outputLabel>
</h:form>
</f:view>

Now in process.jsp the back bean can be accessed as shown below

File name : process.jsp
..
<%
ServerInfo mbean = (ServerInfo) request.getSession().getAttribute("ServerInfoBean");
String server = mbean.getServer();
Out.print(“server name read from the jsf back bean =” +server)

%>


Read custom created XML file from a Groovy/Java class in a J2EE Web Application

I have a following xml file that I created to store the application name and Application Owner email address

//File name: EmailInfo.xml

< emailInfo>
< application> < name> Saleways < /name> < email> david@david.com< /email> < /application>
< application> < name> Mercantile House< /name> < email> binod@hotmail.com< /email> < /application>
< application> < name> BishowShop< /name> < email> bishow@hotmail.com< /email> < /application>
< /emailInfo>


Now I have a J2EE application that contains a Groovy or a Java class that access the above XML file. The method to access above html file using Groovy is presented below. Note that the xml file resides on the same location where the class exists.


def appName=[]
def appEmail=[]
java.net.URL url= this.getClass().getClassLoader().getResource("EmailInfo.xml");
java.net.URI uri = new URI(url.toString())
File f=new File(uri)
def emailInfo = new XmlSlurper().parse(f) //Specific to groovy
emailInfo.application.name.each {appName += it} //specific to groovy
emailInfo.application.email.each {appEmail += it} // specific to groovy

You simply can modify the above code for java classes. The final result for the above code is that appName contains the list of the Name and appEmail contains the list of the Email address. You can put it into hash map as below.

def emailMap=[:] //define an empty map
for(i in 0 .. appName.size()-1)
emailMap.put(appName[i].toString(),appEmail[i].toString())

Now you simply can access the email address of a person as shown below

println emailMap[“Mercantile House”] //prints binod@hotmail.com


Welcome to my Technical Blog!

I create this blog so that i can share all the technical stuffs that i came across as a software engineer in J2EE Technologies. I will be glad to receive your feedback for every post and share your idea on the postings.
Welcome you all.
~Bishow