The beanshell accessor executes BeanShell language scripts.

The operator argument specifies the resource to be executed as a program. This resource may be either a plain/text script or an XML document with the script specified as the text of the root element. When encapsulating a script in XML it is strongly advisable to enclose your script inside a CDATA section, for example:

<script><![CDATA[ ...your script .. ]]></script>

main() is mandatory

A BeanShell script must define a main() method which is invoked when the script is executed. This is a performance optimization. BeanShell allows code to be executed outside the scope of a method, however this restriction allows the NetKernel Scripting Framework to perform pre-execution parsing. For small scripts this yields a performance gain of approximately 5x.

Script Context

When executed, each script is provided an instance of the INKFConvenienceHelper class as the local variable context. The context variable has two purposes. It supports introspection of the request which initiated the script and it allows sub-requests to be issued. For more details see the NKF Reference Guide.

Once a response object is created:

response=context.createResponseFrom(...);

it will be returned via the context when the script exits.

Parameters

Parameters can be passed to a script using named arguments. Argument values are available within the script through the context using the this:param URI address space convention.

For example if the beanshell accessor is requested with...

active:[email protected][email protected]

The myargument parameter can be obtained inside the script through the context object by requesting the URI "this:param:myargument"...

context.source("this:param:myargument")

Classpath

A BeanShell script inherits the classpath of the execution context. The order for locating a class is as follows:

1. The ext-script module
2. The superstack back to the module where the beanshell accessor was invoked
3. The libraries and imports of the module originating the script execution request.
4. The NetKernel core classes
5. The Java VM classpath

A Java class can be imported into a script with a regular Java import statement...

import java.util.Random;

Script Libraries

Libraries of dynamic BeanShell scripts can be loaded from the execution context. Library scripts may be classes, methods or global variables. They can be loaded into the script context with the following code which must be located outside the scripts main() method:

import com.ten60.netkernel.urii.aspect.IAspectString;
myLibraryURI = "libs/library1.bsh";
i=new bsh.Interpreter();
i.setNameSpace(this.namespace);
i.eval( context.sourceAspect( myLibraryURI, IAspectString.class ).getString() );

Example

This example shows a BeanShell script performing an XSLT transformation, logging the result and returning the result as the response:

import org.ten60.netkernel.layer1.nkf.*;
import org.ten60.netkernel.layer1.representation.IURRepresentation;

void main()
{
  //Create and issue XSLT request
  sr=context.createSubRequest();
  sr.setURI("active:xslt");
  sr.addArgument("operand","data1.xml");
  sr.addArgument("operator","style1.xsl");
  rep=context.issueSubRequest(sr);
    
  //Log result
  sr=context.createSubRequest();
  sr.setURI("active:log");
  sr.addArgument("operand",rep);
  context.issueSubRequest(sr);

  //Create responses and exit
  INKFResponse resp=context.createResponseFrom(rep);
}