Helma NG
========

Helma NG is a Javascript runtime and web application framework written in Java.
"NG" stands for "next generation", meaning that it is a more of a rewrite of
Helma 1 than simply a new version.

Helma NG consists of several components that can be used together or alone:

  1) A compact JavaScript runtime environment based on Mozilla Rhino. It adds
     to Rhino a reloading module system that is compatible to the ServerJS
     Securable Module proposal.

  2) An interactive shell with support for autocompletion and history.

  3) A module library implemented in JavaScript, covering basic functionality
     such as extensions to the built-in objects, file I/O, logging, persistence,
     client and server side HTTP support and more.

JavaScript Runtime
==================

The Helma JavaScript runtime is based on Mozilla Rhino and supports
JavaScript 1.7 with partial support for JavaScript 1.8 features.

To run a script with Helma, simply pass it as an argument to run.jar:

    java -jar run.jar somepath/mainfile.js

If you run a script that is contained in Helma's module path you can also
use the simpler abstract module name instead of the file name:

    java -jar run.jar helma.unittest

Helma takes the first command line argument after run.jar that does not start
with a "-" as script name. Everything coming after the script name is passed
to the script as arguments.

   java -jar run.jar [option] ... [file] [arg] ...

JavaScript Shell
================

To start the interactive Helma shell start run.jar without a script file:

    java -jar run.jar

This starts the Helma shell with the current directory in its module path.
The module path is the list of places Helma looks for scripts when asked to
import something. It should contain your application directory. Helma always
adds the modules directory to the end of the module path.

You can also start the interactive Helma shell when running a script using
the -i or --interactive flag:

    java -jar run.jar -i dir/script.js

This will add the script's parent directory to the module path (in this case
"dir", run the script, then start the shell.


Web Framework
=============

The Helma Web Framework is a web application framework written mostly in JavaScript
built on top of the Helma Runtime.

To run the demo application that is part of Helma NG run the following command:

    java -jar run.jar apps/demo/main.js

This starts and serves the demo web app on port 8080:

    http://localhost:8080/

The demo app showcases a number of tools and libraries to build web apps.
As Helma NG is still pretty young, many features found in Helma 1.6 are still
missing, most notably a persistence layer. These features are currently being
implemented.

The exciting thing is thatit will be possible to implement much of it in
Javascript, meaning you can help doing so without hacking on helma core.
The new modular concept will even allow to use helma with several frameworks,
even on the same server instance.

Visit http://dev.helma.org/ng/ and join the Helma NG mailing list to keep up
with Helma NG core and module development! 

Global Functions
================

In addition to standard Javascript functionality, some useful functions
Helma adds are:

import(module);
include(module);
require(module);

    These functions load Javascript modules and make them available to the
    current scope in different ways. See
    http://dev.helma.org/ng/Modules+and+Scopes/ for more info.

    Helma first tries to resolve the path relative to the location of the
    module calling this method. If that fails, it looks for the resource
    in the repository path, which usually consists of the current directory
    (shell) or app directory (web apps) and the modules directory.

    The module path can be set by passing one or more script directories on
    the command line. As a fallback, Helma checks the helma.modulepath
    System property:

        java -Dhelma.modulepath=myapp,mylibs -jar run.jar

addToClasspath(jarfile)

    This function adds a jar file or directory to the classpath. by default,
    all jar files in the lib directory are included in the classpath. You
    can add also other jar files by starting helma with

       java -Dhelma.classpath=foo.jar,lib0/,lib1/*,lib/** -jar run.jar

getResource(path)

    This loads a resource object. See the import functions above for a
    detailed explanation of helma.modulepath and resource lookup.

Building Helma
==============

To build helma yourself follow these steps:

  Check out helma from subversion:

      svn co https://dev.helma.org/svn/helma-ng/trunk/ helma-ng

  Change to the helma-ng directory and run ant to compile:

      ant jar

If this succeeds you should be able to start the helma shell and runtime
as described above.