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Introduction

This document is intended to collect and track ideas about the Debugger Feature of the JavaFX Plugin for the NetBeans IDE. It will be used as a source for the Debugger Feature Specification. It is also used for refining the Debugger Feature Requirements.

Debugging process

Debugging is a part of the the software development process. Debugging may be performed after some Quality Assurance (QA) activity that showed a negative result. Also, the Debugging process may be initiated by the developer. In this case, the developer will use own expectations instead of the formal requirements.

Context of the Debugging process

The IDEF0 approach is used to describe the Context of the Debugging process.

Java SE Debugging

The Java technology offers two interaction levels with a target VM on the Java SE platform: Native level and Java level.

Resources:

• Java Platform Debugger Architecture (JPDA) on the java.sun.com
• Java(tm) Debug Wire Protocol The (JDWP) is the protocol used for communication between a debugger and the Java virtual machine (VM) which it debugs (hereafter called the target VM).
• Sun VM Invocation Options for debugging

Native level

We need take into account:

• JVM TI may not be available in all implementations of the Java(tm) virtual machine.
• JVM TI was introduced in J2SE 5.0 and replaced JVMDI and JVMPI.
• JVMDI was removed in Java SE 6 and JVMPI will be removed in Java SE 7.

Resources:

• JVM(tm) Tool Interface Version 1.1 (JVM TI)
• JVM TI Bugs

Java level

• Java(tm) Debug Interface (JDI) is a high level Java API providing information useful for debuggers and similiar systems needing access to the running state of a (usually remote) virtual machine.

Resources:

JVM Implementation

TODO There are Java Virtual Machines with the different feature sets. See com.sun.jdi.VirtualMachine.canXXX() methods.

Java SE Debugging in the NetBeans IDE

Modules:

• debuggercore Debugger Core - Debugger APIs, UI and infrastructure
• debuggerjpda JPDA Debugger Implementation Plug-In
• debuggertools [obsolete] JDK1.1 (sun.tools.debug.*) Debugger Impl. Plug-In

Resources:

• NetBeans IDE 6.0 Features - Debugger
• Getting Started With the NetBeans IDE Tutorial

Java ME Debugging in the NetBeans IDE

Resources:

• JavaFX Mobile on the java.sun.com
• Get started with On-device Debugging for NetBeans

JavaFX Debugging vs. Java SE Debugging

Resources:

• Article Using JavaFX Script Objects in Java Programs by Michael Heinrichs, May 2008 on the Sun Developer Network (SDN) site.

Subjects of debugging

In both cases (Java and JavaFX), a JVM is the native application under debug.

There are the following subjects of debugging on the Java level:

Subject	Java	JavaFX
Set of the related Java classes	* pure Java app/lib	* pure JavaFX app and JavaFX+Java lib * stand-alone JavaFX script
Stand-alone Java class	* Main class, * Any class + Main test class/framework	XXXXXX

TODO Applet

Entry points

Java	JavaFX
The public static void main(String [] args) method in the public class	A first executable moduleItem in the JavaFX script, i.e. either statement or expression. See the ANTLR grammar of the JavaFX language.

TODO Applet

Script Context

The Script Context is established by the JSR 223: Scripting for the JavaTM Platform API as the interface javax.script.ScriptContext. According to the specification each script has own context. Script context provides accessibility of entities from inside of the script, including:

• Set of Attributes. Attribute is the named Java object, whose name is String.
• Set of Bindings. Bindings is the mapping of key/value pairs, all of whose keys are Strings, i.e it is a set of the named Java objects.
• Error Writer - a Writer used to display error output.
• Reader - a Reader to be used by the script to read input.
• Writer - a Writer for scripts to use when displaying output.

Both Attributes and Bindings are associated with a scope. Each scope is identified by the int value. There are two predefined scopes ENGINE_SCOPE (int value = 100) and GLOBAL_SCOPE (int value = 200). There are no way to find symbolic names for other user-defined scopes.

There are predefined names that are defined as Java language String constants in the interface javax.script.ScriptEngine:

Java Constant Name	Java Constant Value	Comments
ARGV	"javax.script.argv"	an array of positional arguments that are passed to a script.
ENGINE	"javax.script.engine"	the name of the ScriptEngine implementation.
ENGINE_VERSION	"javax.script.engine_version"	the version of the ScriptEngine implementation.
FILENAME	"javax.script.filename"	the name of the file being executed.
LANGUAGE	"javax.script.language"	the full name of Scripting Language supported by the implementation.
LANGUAGE_VERSION	"javax.script.language_version"	the version of the scripting language supported by the implementation.
NAME	"javax.script.name"	the short name of the scripting language. The name is used by the ScriptEngineManager to locate a ScriptEngine with a given name in the getEngineByName method.

Also, there are pseudo-variables generated by the JavaFX Script compiler:

JavaFX Constant Name	Comments
__DIR__	A URL of the directory where the JavaFX module .class file is placed. This value is based on the value of the __FILE__ pseudo-variable. The expression new java.net.URL(__FILE__, ".") is used to calculate that value (See specification of the constructor URL(URL context, String spec)).
__FILE__	A URL of the JavaFX module .class file.
__ARGS__	A sequence of positional arguments that are passed to a script. Note, elements of the sequence are the same as elements of the array ARGV that is mentioned in the previous table.

JSR 45

Whether the JSR 45: Debugging Support for Other Languages has any relations or impacts on the JavaFX debugging?

JavaFX Script Language and JavaFX Programs

Resources:

• JavaFX API
• Java API of JavaFX

Debugging a program written on a object-oriented language

Debugging a program written on a declarative language

Debugging human interfaces of the JavaFX Programs

Debugging a GUI

• View of the GUI Components. The view lets to investigate hierarchical trees of the GUI components, including their properties and relations.
• Event log.
• User action recorder.
• User action generator. Should be possible to synchronize the generator with the GUI preview.

Debugging an Audio UI

Debugging a Voice UI

Resources: Voice User Interface (VUI)

Debugging a JavaFX program on other Java platforms

Java ME

Java TV

Debugging Complex Strings

Debugging Triggers

Debugging Binding

Debugging a Program with Loadable Recourses

TODO TRANSLATION_KEY, I18N artifacts

Debugging Threads

Debugging Remote Application

Debugging Distributed Application

Proposing Solutions

Related Documents

• [#1] How do I debug an applet?
• [#2] How can I run/debug a program in NetBeans with certain environment variables set to necessary values?
• [#3] How can I run/debug a program in NetBeans with certain Java system properties set to certain values?
• [#4] Debugging NetBeans with the NetBeans debugger
• [#5] NetBeans Debugger Project
• [#6] Java Platform Debugger Architecture - FAQs
• [#7] JSR 45: Debugging Support for Other Languages This specification establishes standardized tools for correlating JavaTM virtual machine byte code to source code of languages other than the JavaTM programming language.
• [#8] JSR 292: Supporting Dynamically Typed Languages on the JavaTM Platform Add a new bytecode, invokedynamic, that supports efficient and flexible execution of method invocations in the absence of static type information.

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