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org.apache.bsf.engines.netrexx
Class NetRexxEngine  

java.lang.Object
  org.apache.bsf.util.BSFEngineImpl
      org.apache.bsf.engines.netrexx.NetRexxEngine

All Implemented Interfaces:

org.apache.bsf.BSFEngine, java.util.EventListener, java.beans.PropertyChangeListener

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public class NetRexxEngine

extends org.apache.bsf.util.BSFEngineImpl

This is the interface to NetRexx from the Bean Scripting Framework.

The NetRexx code must be written script-style, without a "class" or "properties" section preceeding the executable code. The NetRexxEngine will generate a prefix for this code:

 
 class $$CLASSNAME$$;
 method BSFNetRexxEngineEntry(bsf=org.apache.bsf.BSFManager) public static;
 
 

$$CLASSNAME$$ will be replaced by a generated classname of the form BSFNetRexx*, and the bsf parameter can be used to retrieve application objects registered with the Bean Scripting Framework.

If you use the placeholder string $$CLASSNAME$$ elsewhere in your script -- including within text strings -- BSFNetRexxEngine will replace it with the generated name of the class before the NetRexx code is compiled.

If you need to use full NetRexx functionality, we recommend that your NetRexx script define and invoke a "minor class", with or without the "dependent" keyword as suits your needs. You'll have to use $$CLASSNAME$$ in naming the minor class, since the name of the main class is synthesized; for example, to create the minor class "bar" you'd write "class $$CLASSNAME$$.Bar".

Hazards:

Since NetRexx has to be _compiled_ to a Java classfile, invoking it involves a fair amount of computation to load and execute the compiler. We are currently making an attempt to manage that by caching the class after it has been loaded, but the indexing is fairly primitive; we hash against the script string to find the class for it.

Minor-class .class files are now being deleted after the major class loads. This coould potentially cause problems.

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Nested Class Summary
private  class	NetRexxEngine.GeneratedFile

 

Field Summary
private  boolean	bsfHandleCreated
(package private) static java.util.Hashtable	codeToClass
(package private)  org.apache.bsf.util.BSFFunctions	mgrfuncs
(package private)  java.lang.String	minorPrefix
(package private) static java.lang.String	placeholder
(package private) static java.lang.String	serializeCompilation
private static int	uniqueFileOffset           Create a scratchfile, open it for writing, return its name.

 

Fields inherited from class org.apache.bsf.util.BSFEngineImpl

classLoader, classPath, dbgmgr, declaredBeans, lang, mgr, tempDir

 

Constructor Summary

NetRexxEngine()           Constructor.

 

Method Summary
java.lang.Object	call(java.lang.Object object, java.lang.String method, java.lang.Object[] args)           Return an object from an extension.
(package private)  java.lang.Object	callStatic(java.lang.Class rexxclass, java.lang.String method, java.lang.Object[] args)           Invoke a static method.
void	declareBean(org.apache.bsf.BSFDeclaredBean bean)           Declare a bean after the engine has been started.
java.lang.Object	eval(java.lang.String source, int lineNo, int columnNo, java.lang.Object script)           Override impl of execute.
void	exec(java.lang.String source, int lineNo, int columnNo, java.lang.Object script)           Override impl of execute.
java.lang.Object	execEvalShared(java.lang.String source, int lineNo, int columnNo, java.lang.Object oscript, boolean returnsObject)           This is shared code for the exec() and eval() operations.
void	initialize(org.apache.bsf.BSFManager mgr, java.lang.String lang, java.util.Vector declaredBeans)           initialize the engine; called right after construction by the manager.
private  NetRexxEngine.GeneratedFile	openUniqueFile(java.lang.String directory, java.lang.String prefix, java.lang.String suffix)
void	undeclareBean(org.apache.bsf.BSFDeclaredBean bean)           Undeclare a previously declared bean.

 

Methods inherited from class org.apache.bsf.util.BSFEngineImpl

apply, compileApply, compileExpr, compileScript, disconnectedDebuggerNotify, getSpecificDebuggingInterface, placeBreakpointAtLine, placeBreakpointAtOffset, propertyChange, removeBreakpoint, setEntryExit, terminate

 

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

 

Field Detail

mgrfuncs

org.apache.bsf.util.BSFFunctions mgrfuncs

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bsfHandleCreated

private boolean bsfHandleCreated

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codeToClass

static java.util.Hashtable codeToClass

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serializeCompilation

static java.lang.String serializeCompilation

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placeholder

static java.lang.String placeholder

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minorPrefix

java.lang.String minorPrefix

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uniqueFileOffset

private static int uniqueFileOffset

Create a scratchfile, open it for writing, return its name. Relies on the filesystem to provide us with uniqueness testing. NOTE THAT uniqueFileOffset continues to count; we don't want to risk reusing a classname we have previously loaded in this session even if the classfile has been deleted. I've made the offset static, due to concerns about reuse/reentrancy of the NetRexx engine.

Constructor Detail

NetRexxEngine

public NetRexxEngine()

Constructor.

Method Detail

call

public java.lang.Object call(java.lang.Object object,
                             java.lang.String method,
                             java.lang.Object[] args)
                      throws org.apache.bsf.BSFException

Return an object from an extension.

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callStatic

java.lang.Object callStatic(java.lang.Class rexxclass,
                            java.lang.String method,
                            java.lang.Object[] args)
                      throws org.apache.bsf.BSFException

Invoke a static method.

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declareBean

public void declareBean(org.apache.bsf.BSFDeclaredBean bean)
                 throws org.apache.bsf.BSFException

Description copied from interface: org.apache.bsf.BSFEngine

Declare a bean after the engine has been started. Declared beans are beans that are named and which the engine must make available to the scripts it runs in the most first class way possible.

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eval

public java.lang.Object eval(java.lang.String source,
                             int lineNo,
                             int columnNo,
                             java.lang.Object script)
                      throws org.apache.bsf.BSFException

Override impl of execute. In NetRexx, methods which do not wish to return a value should be invoked via exec, which will cause them to be generated without the "returns" clause. Those which wish to return a value should call eval instead. which will add "returns java.lang.Object" to the header. Note: It would be nice to have the "real" return type avaialable, so we could do something more type-safe than Object, and so we could return primitive types without having to enclose them in their object wrappers. BSF does not currently support that concept.

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exec

public void exec(java.lang.String source,
                 int lineNo,
                 int columnNo,
                 java.lang.Object script)
          throws org.apache.bsf.BSFException

Override impl of execute. In NetRexx, methods which do not wish to return a value should be invoked via exec, which will cause them to be generated without the "returns" clause. Those which wish to return a value should call eval instead. which will add "returns java.lang.Object" to the header.

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execEvalShared

public java.lang.Object execEvalShared(java.lang.String source,
                                       int lineNo,
                                       int columnNo,
                                       java.lang.Object oscript,
                                       boolean returnsObject)
                                throws org.apache.bsf.BSFException

This is shared code for the exec() and eval() operations. It will evaluate a string containing a NetRexx method body -- which may be as simple as a single return statement. It should store the "bsf" handle where the script can get to it, for callback purposes.

Note that NetRexx compilation imposes serious overhead -- 11 seconds for the first compile, about 3 thereafter -- but in exchange you get Java-like speeds once the classes have been created (minus the cache lookup cost).

Nobody knows whether javac is threadsafe. I'm going to serialize access to the compilers to protect it.

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initialize

public void initialize(org.apache.bsf.BSFManager mgr,
                       java.lang.String lang,
                       java.util.Vector declaredBeans)
                throws org.apache.bsf.BSFException

Description copied from class: org.apache.bsf.util.BSFEngineImpl

initialize the engine; called right after construction by the manager. Declared beans are simply kept in a vector and that's it. Subclasses must do whatever they want with it.

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openUniqueFile

private NetRexxEngine.GeneratedFile openUniqueFile(java.lang.String directory,
                                                   java.lang.String prefix,
                                                   java.lang.String suffix)

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undeclareBean

public void undeclareBean(org.apache.bsf.BSFDeclaredBean bean)
                   throws org.apache.bsf.BSFException

Description copied from interface: org.apache.bsf.BSFEngine

Undeclare a previously declared bean.

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Overview  Package   Class  Use  Deprecated  Index
Home >> All >> org >> apache >> bsf >> engines >> [ netrexx overview ]	PREV CLASS  NEXT CLASS
SUMMARY:  JAVADOC |  SOURCE |  DOWNLOAD | NESTED | FIELD | CONSTR | METHOD	DETAIL: FIELD | CONSTR | METHOD

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