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JavaTM Platform Debugger Architecture

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Architecture Overview

The JavaTM Platform Debugger Architecture is structured as follows:
             Components                         Debugger Interfaces

                /    |--------------|
               /     |     VM       |
 debuggee ----(      |--------------|  <------- JVMDI - Java VM Debug Interface
               \     |   back-end   |
                \    |--------------|
                /           |
 comm channel -(            |  <--------------- JDWP - Java Debug Wire Protocol
                \           |
                     |--------------|
                     | front-end    |
                     |--------------|  <------- JDI - Java Debug Interface
                     |      UI      |
                     |--------------|

What is the Java Platform Debugger Architecture (JPDA)?

JPDA is a multi-tiered debugging architecture that allows tools developers to easily create debugger applications which run portably across platforms, virtual machine (VM) implementations and SDK versions.

JPDA consists of three layers:

JVMDI - Java VM Debug Interface
Defines the debugging services a VM provides.
JDWP - Java Debug Wire Protocol
Defines the communication between debuggee and debugger processes.
JDI - Java Debug Interface
Defines a high-level Java language interface which tool developers can easily use to write remote debugger applications.

Reference implementation

In addition to the specification of these interfaces, Sun Microsystems also provides a reference implementation, which consists of: This provides a layered implementation in which any layer may be substituted.

Using JPDA

A debugger developer may hook into JPDA at any layer. Since the JDI is the highest level and easiest to use we encourage developers to use this interface. Suppose a company develops a debugger using JDI. They can use it with the reference implementation and it will automatically work with the VMs and platforms Sun supports. It can also work, for example, with the reference implementation front-end and a debuggee running another company's VM that implements JDWP (which might use or by-pass JVMDI).

Some debuggers are built on top of lower layers, JDWP (for example if the front-end is not written in the Java language) or JVMDI (for specialized debuggers which need low-level functionality).


Components

debuggee

Java Virtual Machine (VM)

back-end

communications channel

 

front-end

 

User Interface (UI)

 


Debugger Interfaces

Java Virtual Machine Debugger Interface (JVMDI)

Java Debug Wire Protocol (JDWP)

Java Debug Interface (JDI)



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