Embeded open source java repoting library

Have you ever need to create a report and want to change it's content or design or send it preameters then you export it as PDF, XLS or CSV from your java code, sure yes.

Open source java library it is now available from JasperSoft company which is the market leader in open source business intelligence tools, the reporting libraries are called 'Jasper Reports '.

Jasper Reports, it is the world's most widely used open source reporting engine. 

you can download its JAR from:

http://jasperforge.org/plugins/esp_frs/?group_id=102

then choose the required pakage version, and choose download.

after finishing download you will find jasperreports-version.jar file is located on your hard disk.

You can copy this JAR file under your lib folder under your java project,

Now, sure you need to create you first report using Jasper reports, there is a GUI designer for creating reports by only drag ad drop report components from toolbox.

This designer is called IReport, which simplifies the development of even the most complex reports. 

you can download it from this link:

http://sourceforge.net/project/showfiles.php?group_id=64348&package_id=64215

and choose your suitable installation, also IReport is now available as a plugin for NetBeans IDE 

http://sourceforge.net/project/showfiles.php?group_id=64348&package_id=263429

a tutorial for IReport to start creating reports using it, is avaliable for download from:

http://www.4shared.com/get/53621480/f3076340/ApressTheDefinitiveGuidetoiReport_2007_BBL1590599284.html

and starts to access it from your java code which will be available soon in a new post after you will finish creating your reports using IReport.

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Original Post By : Asmaa Mahmoud "http://www.new.facebook.com/topic.php?topic=6910&post=25848&uid=5425349500#post25848"

Optimizing the conversion of numbers to strings and vise-versa

Read this interesting article to see how the guys at Mainsoft optimized the conversion of numbers to strings and vise-versa by more than 2.6x. Their goal was to leverage the performance of text-based internet protocol implementations such as XML and HTML.

The article also introduces a valuable comparison to conversion algorithms in .Net. Java. It's a good reminder for all of us to keep looking for improvements and stop taking things for granted. The source code is available too.

Signed Java Applets

Hey, welcome back with a new blog !! today I am talking about both Java and web, more clearly Java Applets

Let us see the problem. Days ago, I was developing a Java Applet that capture a snapshot for Desktop and send it to Flash movie embedded in the same HTML page to provide Desktop Sharing (viewing share not remote access) facility for our web application. I finished developing the applet on Eclipse IDE and it was running well. When embedding it in HTML page, it gave java.security.AccessControlException: access denied (java.awt.AWTPermission createRobot)
(as I used AWT package to capture the screen). So, what is the problem ?!!

I surfed the net for such problem and it was the first time to deal with Java security policy. This policy resides in java.policy file located at $JAVA_HOME\jre\lib\security. Problem is that Applets, unlike Applications, are not trusted by default by Java security policy. It is restricted for some operations like accessing the local file system, asking for socket connection,... etc. The solution is what called Signed Java Applet.

Before completing with Java Signed Applet, let us see why the applet run on Eclipse IDE the first time. When running the applet in Applet Viewer through Eclipse, Eclipse generates a policy file in the folder contains this applet called java.policy.applet and associate it with the applet. The content of the file (for my applet) was as following:

/* AUTOMATICALLY GENERATED ON Tue Apr 16 17:20:59 EDT 2002*/
/* DO NOT EDIT */

grant {
permission java.security.AllPermission;
};

It is clear that it allows the developer applet to do everything assuming that developers (which use Eclipse IDE) are mature enough to take care about disasters may harm their local computers. So everything is running on Applet Viewer.

Java Signed Applet is an applet associated with a digital certificate. Digital certificates are authored by trustworthy authorities. Signing an Applet needs to get a certificate from one of these authorities, which is most of time costs money for sure, so users can trust your applet and give it permission to do its operation. Digital certificate contains the holder party(which is you in this case) besides the certificate authority (e.g. Sun MicroSystems). No specific authorities monopoly giving certificates, but companies have good reputation or something like that can give this certificate. You can create your own certificate for developing and testing issues.

After singing the applet, browser will pop up a dialog to users when the applet is loading displaying the digital certificate associated with the applet and let the user permit the applet to be authorized on his computer or reject the certificate which let the applet behave like unsigned one.

We may talk about digital certificates in details later; but at a glance, it depends on public key encryption algorithms (e.g. RSA algorithm, click here to read more about RSA) that generates a pair of public and private keys and use this to verify the validity of the certificate within its expiration period.

Now, let us see how to sign our applets with our own digital certificate for development purposes:

1. Create your code for the applet as usual.
It is not necessary to set any permissions or use security managers in
the code.

2. Install JDK 1.5
Path for use of the following commands: $JAVA_HOME\bin
(commands are keytool, jarsigner)
Password for the keystore is any password.

3. Generate key:
keytool -genkey -keyalg rsa -alias tstkey
Enter keystore password: ******* (any password)
What is your first and last name?
[Unknown]: Your Name
What is the name of your organizational unit?
[Unknown]: YourUnit
What is the name of your organization?
[Unknown]: YourOrg
What is the name of your City or Locality?
[Unknown]: YourCity
What is the name of your State or Province?
[Unknown]: YS
What is the two-letter country code for this unit?
[Unknown]: US
Is CN=Your Name, OU=YourUnit, O=YourOrg, L=YourCity, ST=YS, C=US
correct?
[no]: yes

(wait...)

Enter key password for tstkey
(RETURN if same as keystore password):

(press [enter])

4. Export key: keytool -export -alias tstkey -file tstcert.crt

Enter keystore password: *******
Certificate stored in file tstcert.crt

5. Encapsulate your applet in a JAR file (click here to read how to create JAR files).

6. Sign JAR:
jarsigner signedApplet.jar tstkey
Enter Passphrase for keystore: *******

8. Verifiy Signing: jarsigner -verify -verbose -certs signedApplet.jar

130 Thu Feb 12 13:04:12 GMT+02:00 2008 META-INF/MANIFEST.MF
183 Thu Feb 12 13:04:12 GMT+02:00 2008 META-INF/TSTKEY.SF
920 Thu Feb 12 13:04:12 GMT+02:00 2008 META-INF/TSTKEY.RSA
Thu Feb 12 12:58:28 GMT+02:00 2008 META-INF/
smk 849 Thu Feb 12 12:49:04 GMT+02:00 2008 SignedApplet.class

X.509, CN=Your Name, OU=YourUnit, O=YourOrg, L=YourCity, ST=YS, C=US
(tstkey)

s = signature was verified
m = entry is listed in manifest
k = at least one certificate was found in keystore
i = at least one certificate was found in identity scope

jar verified.

9. Create HTML file for use of the Applet using tag

<"applet" code="SignedApplet.class" width=100 height=140 archive="signedApplet.jar">"</"applet">

where signedApplet.jar reside next to HTML file and SignedApplet.class encapsulated in it.


10. Run HTML page and test your applet.

I tested it on my PC using JDK 1.5 Update 8 to sign the applet and take the applet on my laptop and run well.

I hope this helps.

JavaScript Function Closure

Coming from a C++/JAVA background, it was hard for me to assimilate the concept of Function Closure in JavaScript. Now that I understand it, I'd like to share it here with you. Seriously, it's best explained by example than description. Here's an example.

var thingsToDo = {};

function initializeThingsToDo() {
var food= {
    name: "Ramen",
    type: "Tokatsu"
};
thingsToDo.eat = function() {
    alert("I'm going to eat: " + food.name);
}
}

//Execute
initializeThingsToDo();
thingsToDo.eat();

Okay, what did I do here? First, I created an empty (global) Object called "thingsToDo", then I added a global function called "initializeThingsToDo". Inside this function I defined food object. I referenced the global object "thingsToDo" and attached a dynamic function called "eat" in the object.

After the code definitions, I ran the global function initializeThingsToDo, and called the method thingsToDo.eat().

I know you would say that this is crazy because when I ran thingsToDo.eat(), the method uses the food object but it's already out of scope.

//Execute
initializeThingsToDo();
thingsToDo.eat(); // When this is executed,
               // the food object is already out of scope!

Na ah?! Not in JavaScript. You see, when you run the code, JavaScript will create a closure to the food object. After that, it saves it in the memory. The interpreter knows that it will be used for later. (It doesn't deallocate the food object in the memory. )

The power of function closure is well executed when you use AJAX. When you define your AJAX callback function, it gets called asynchronously. It creates a closure and call the objects/functions when it's ready.

If you are not familiar with JavaScript Object and Functions, you can read these links:

Java vs. JavaScript object
JavaScript usign Prototype.js
JavaScript Function

Source:
http://liminescence.blogspot.com/2007/11/javascript-function-closure.html