For Java Users
By James Huang May 2003 
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This article is to help Java programmers understand JudoScript, and possibly ease some fears about a new language.
It explains the difference between Java and scripting languages, and briefly mentions some of JudoScript's important features.
It advocates to use Java in addition to programming, and JudoScript is the product of and facilitator for this ideal.
Java programmers are loyal to and take great pride in the language.
Some of them want to use Java for everything, and I am definitely one of these, because Java has
embodied almost all computing areas, and open-source projects cover even more.
A few projects tended to use Java directly as a scripting language by interpreting exactly the same language.
Some innovated by defining a scripting langauge with a syntax very close to Java and enjoys great success.
Others ported existing languages like Python, JavaScript, TCL, etc.
But somehow I felt they are not enough, because all of these languages are not too far off
the idea of using Java itself as a scripting language. Well, what is wrong with that idea?
As we know, Java is a system language, with low-level, fine-granularity APIs designed for building software.
Using Java for everyday tasks is tedious even with an "easier" language.
Think about copying a tree of files into a zip archive, or sending an e-mail, or process an XML document with SAX....
how much coding is involved?
If possible, I would rather focus on the tasks at hand, not worrying too much about Java classes and APIs --
what I call "implementational details" that at times become nuisances.
(See the definition of scripting in the White Paper.)
Being an object-based platform, Java is a dream platform for scripting languages.
Object-based platforms provide superior modularity, reusability and scriptability.
Take Windows as an example. With a capable tool, you can instantiate an ActiveX control,
access its properties and use its services (methods).
An object-oriented language does not necessarily guarantee scriptability.
For instance, there is no such thing as a "C++ object" at run-time.
Java, being a platform and a language, make language objects and run-time objects the same.
Run-time objects can all be dynamically inspected, instantiated and used.
Java is a dream platform for scripting languages and language designers.
It is clearly an ideal basis for a cross-platform, cross-RDBMS, readily usable, easily extensible, powerful scripting tool.
Java is the future of scripting.
In mid-2001, I dreamed about a tool that does: (1) JDBC scripting, (2) XML scripting and (3) EJB scripting.
By the end of that year, a new, all-around scripting language was born.
I was about to name it "JavaScript", only to receive a name-already-taken exception.
Then, this new language was named JudoScript, because I like to have letter J in the front.
Scripting languages have some fundamental differences than system languages like Java and C.
In the rest of this article, we use JudoScript as an example of scripting language and Java as system language.
The most important difference is probably the handling of variables.
In Java, variables are statically typed; their types determines their uses. For instance, in this example,
String s = " toys";
System.out.println(2 + s);
In JudoScript, a variable is a container for any values.
A value is either of a simple type (number or string) or an object of some kind.
In the former situation, the value is weakly typed, so the uses determine what type it is intended.
For instance,
x = '1';
y = 1;
println x + y; // print out: 2
println x @ y; // print out: 11
The @ operator is the only one in JudoScript that is different from its Java's counterpart -- string concatenation.
If a variable holds an object, normally they are strongly typed and you can only use their defined properties and methods, like this:
x = new java::java.util.Vector;
println x.size(); // print out: 0
except for some Java objects like java.lang.Number instances:
x = new java::java.lang.Integer(5);
print x + 1; // print out: 6
As a mordern scripting language, JudoScript uses a hybrid programming model of procedural, object-oriented and dynamic programming.
You can simply type in statements in the global scope and run, or organize code into functions, classes and threads.
It is a very powerful programming system.
Scripting languages have so-called "syntactic sugar" that make coding easier and more relaxed. For instance,
x = [[*
Scripting is to do things easily, intuitively, obviously and accurately, so
much so that when another person with the same domain knowledge sees a chunk of
code, he immediately understands it without even a hint of reasoning (ideally).
Scripting Support means very-high-abstraction-level language constructs or even
domain-specific languages.
*]];
this example puts a chunk of text into a variable.
The leading indentations are stripped, so the code can look nice and neat.
Of course not. A powerful language engine is the basis for other good things.
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JudoScript is a totally capable Java scripting langauge.
This is required by our goal of EJB scripting, and is one of the backbones of the language.
Not quite. Interestingly, this is the sole goal of many other Java scripting languages.
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JudoScript has intimate data processing support for relational databases, XML, SGML, text and abstract data such as EJBs.
It is one of its greatest strengths.
JDBC scripting is one of the major reasons for this language.
XML scripting is another major reason for this language.
JudoScript has a special statement for SAX style programming, and also supports DOM and XSLT scripting.
JudoScript supports an SGML statement similar to XML SAX programming:
do 'http://www.yahoo.com' as sgml {
<a>: println 'web link: ', $_.href;
<img>: println 'img link: ', $_.source;
}
In addition to regular file operations, JudoScript has a text file statement:
cnt = 1;
do 'Test.java' as lines {
println cnt :>3, // right-aligned with width 3
': ', $_; // add a line number to the line.
++cnt;
}
EJB scripting is very easy.
JudoScript has a number of convenience system function to get an initial context for popular J2EE products like Weblogic.
Once you have the context, use JNDI to obtain your intended target objects.
It is faster to write an EJB client than Java because you do not have to type all the class names.
With these high-level support, you are empowered to do a lot of things efficiently and effectively.
Do not underestimate the potential of such conveniences. For instance, during a software upgrade,
I conducted a series of data analysis using JudoScript JDBC scripting assisted with data structures,
and eventually led to an optimal solution. This is a good demonstration of the power of JudoScript over sheer SQL.
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JudoScript has many other nifty features that are very useful, and people love them. Check them out!
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JudoScript is a three-in-one language: general-purpose programming, Java scripting and multi-domain support.
Its power comes from the synergy of all three. You can use it to handle many tasks easily; if necessary,
extend it with Java code (you can alias a Java static method as a JudoScript function). I use JudoScript to test Java code,
archive and back up data, do data analysis and reporting, process text files and almost everything.
Java programmers, do something for yourselves! You have been creating cross-platform software for the masses,
why don't you take advantage of Java, an incredible cross-platform resource youselves?
It is capable and powerful; and with JudoScript, it is possible and doable.
Happy using Java!
