Developing with Scripting Languages
NetKernel is written in Java and runs in the Java Runtime Environment (JRE).
Development at the physical level may be done
using Java or one of the scripting languages
supported by NetKernel which includes JavaScript,
Ruby, Python, Groovy and Beanshell.
Resource models
such as the
XML resource model
may contribute additional scripting languages.
These languages are integrated into NetKernel using the
NetKernel Scripting Framework.
This framework adapts the language runtime support
(usually a compiler) to the NetKernel resource-oriented programming model.
Language runtimes are activated by calling the
runtime as an active: service.
NetKernel 3.3 supports:
When the language runtime service is called it is given a reference
to a resource that holds the program to be executed as the
operator argument.
For example, to run a Beanshell program issue a request as follows:
active:beanshell+operator@ffcpl:/myprogram.bsh
When activated, each language runtime, through the NetKernel
Script Language Framework, issues a resource request for the program.
The underlying language system requires the program to be compiled
into Java byte codes.
The language runtimes are designed to convert the representation of the
program from source form to byte code form through transreption.
The internal cache will store the transrepted (compiled) form until
invalidated (such as when a developer modifies the program) at which
time the new source code will be transrepted again into byte code
automatically.
Within each language access to NetKernel and the microkernel is
provided through the
NetKernel Foundation API (NKF)
via an instance of INKFConvenienceHelper which is
given the local name "context".
Passing Parameters
Script language programs have access to argument values
as is discussed in the section on
Parameters and Context.
Java Classpath and Imports
A script inherits the Java
classpath
of the host module within which it is invoked.
This includes the classpaths exported by any modules which are
imported into the host module.
In addition the kernel and layer1 classpaths are always accessible.
The manner in which a scripting language accesses native Java
classes is language specific.
Refer to the language's reference guide for details.
Language Specific Libraries
Each language is able to import its own language's libraries
from the NetKernel address space - refer to each languages'
reference guide for details.
Thread Safety
The ScriptEngine is threadsafe.
Script language programs can and will be executed concurrently.
While you may be able to create local threads in your
script programs, you would be responsible for
their management and local thread safety - we
strongly recommend delegating all
threading and concurrency to NetKernel's microkernel.
Reference
The following versions of script language runtimes
are used in NetKernel 3.3.
Preface
Resource Requests
Scripting Languages
