[Clev-jug] April '08 Cleveland Java Users Group Meeting

[Scott Seighman]

Hi All,

Just a reminder, our monthly scheduled meeting will be held *next 
Wednesday, April 9th at 5:30PM* (pizza and drinks) with the discussion 
beginning at 6:00PM (see map for meeting location: 
http://www.clevelandjava.org/map.htm 
<http://www.clevelandjava.org/map.html>l 
<http://www.clevelandjava.org/map.html>). 

David Caldwell (bio below) will be presenting *Patterns for Integrating 
Java^(TM) and JavaScript^(TM) Technology: Tales from the Front Lines.*  
Dynamic (or "scripting") languages are growing enormously in mind share 
and popularity.  The combined use of Java and dynamic languages on the 
Java platform can boost developer productivity considerably.  In this 
session, David examines several patterns for including dynamic languages 
in a Java technology-based project (see detailed abstract below). 

David will be presenting this topic during *JavaOne* 
<http://java.sun.com/javaone/sf/index.jsp> in May so I'm certain he 
would appreciate feedback from the group as he prepares for the conference.

The agenda:

    * *Eat, Drink, Network (5:30-6:00 PM)*
    * *March Meeting Recap  (6:00-6:20 PM)
      *
    * *News Items (6:20-6:30 PM)
      *
    * *Patterns for Integrating Java^(TM) and JavaScript^(TM)
      Technology: Tales from the Front Lines** (6:30-8:00 PM)
      *

Hope to see you there!

Scott*


David's Bio*

David Caldwell is a Java consultant with over 10 years of experience 
building and architecting Java technology applications, mostly for large 
corporate clients. He is also an active participant in the Mozilla Rhino 
project. Rhino is a JavaScript interpreter which runs on the Java 
platform, and provides the basis for the bundled JavaScript 
implementation included in JDK 6. David is the primary author of its 
support for the E4X (or ECMA-357) standard. E4X is a JavaScript language 
extension which adds XML types to JavaScript's native type system and 
provides a powerful, terse syntax for manipulating and processing XML 
values.

David is an experienced speaker and trainer, having taught Java classes 
in corporate and academic settings and conducted political skills 
training for activist organizations around the United States.

*Abstract *

One of the hottest trends in the Java^(TM) community is the exploding 
use of scripting languages as a way to add more development options to 
the Java technology ecosystem. A series of dynamic languages is 
available for the Java platform, including ports of languages such as 
Python and Ruby (Jython and JRuby) and new languages for the Java 
platform such as Groovy and Scala. These dynamic languages run in the 
Java virtual machine and typically allow access to the underlying Java 
technology-based runtime and Java platform APIs along with a looser type 
system, runtime interpretation, and the ability to embed a language 
interpreter inside a larger application so that scripting can be used to 
add dynamism to a Java platform or Java technology-based application. 
JSR 223 (Scripting for the Java Platform) standardized a set of bindings 
and an API that scripting engines could implement to let Java 
technology-based programs discover their capabilities and execute them 
at runtime.

Arguably the granddaddy of the JVM^(TM) machine dynamic language 
implementations is the Mozilla Foundation's Rhino JavaScript^(TM) 
technology-based interpreter. A version of Rhino is bundled with 
JDK^(TM) release 6 as the only preinstalled scripting engine. Rhino is 
used in many other projects, including Project Phobos, an initiative 
that lets developers leverage JavaScript technology from within the 
GlassFish^(TM) project's Java Platform, Enterprise Edition (Java EE 
platform) environment.

For adding scripting languages to the toolbox, what is the best way to 
integrate them into the development process? Most developers probably 
start using scripting languages because they allow "exploratory 
programming," executing individual lines of code that create and invoke 
methods on Java technology-based objects with instant feedback. But 
more-complex uses of scripting technologies raise questions about how 
exactly to draw the line between Java language code and scripting 
language code and how to get the most out of both tools while minimizing 
the impedance mismatch a multilanguage application creates.

This session's speaker, David Caldwell, is one of the developers on the 
Rhino project and has been using Rhino in various ways to add more 
agility and dynamic behavior to several Java technology-based projects. 
In this session, he examines several patterns for including dynamic 
languages in a Java technology-based project:

    * Using the JavaScript programming language as the primary
      programming language and creating Java technology-based objects on
      demand to leverage the underlying platform
    * Using a peer-based architecture, in which objects from the
      scripting language add dynamic behavior to a Java technology-based
      "peer" instance
    * Using the Java programming language as the primary programming
      language and the JavaScript programming language to extend
      abstract Java classes
    * Creating a script per operation and generating a unique scope for
      each operation, with access to the appropriate Java
      technology-based objects and methods

Attendees who are inexperienced with scripting languages for the Java 
platform will likely be very surprised by how closely Java and 
JavaScript programming language code can be integrated. Architects with 
some exposure to Rhino or one of the other JVM machine dynamic languages 
should come away with a deeper appreciation for the various integration 
strategies available between Java and non-Java programming languages 
running on the JVM machine and which approach(es) might work best on 
their own projects. Developers already using an environment that 
includes an embedded scripting language will learn more techniques for 
using scripts in their embedding and gain insight into the interaction 
model defined by their embedding. And attendees who think Java 
technology is always the answer--or that it is passé and destined to be 
replaced by new tools--will hear thought-provoking critique

-- 
Scott Seighman
Systems Engineer
Sun Microsystems
877.450.8885
scott.seighman at sun.com

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