Writing a custom eclipse debugger

Question

EDIT: There must be some way I can approach this without writing a whole new debugger. I'm currently looking into ways to build on top of the existing java debugger. If anyone has any ideas on how to grab information the Java debugger already has (about stack frames, variables, raw data etc.), that would be really helpful.

--

What I'm trying to do is I have this framework/API built on Java, and I would like to write an eclipse plugin debugger that is customized to my framework. Here is a simple example:

I have two classes, one called scope and one called variable. The scope holds a map of variables. The code is all in java, but I'm using this scope-variable relationship almost like a new language, and would like a variable debug tab that gives me a list of currently active scopes with the variables that are currently stored inside. Here is some code:

import java.util.Hashtable;

public class Scope {
    private Hashtable<String, Variable> variableList = new Hashtable<String, Variable>();

   // constructor 
    public Scope(){

    }

    public void put(String key, Variable v){
        variableList.put(key, v);
    }

    public Variable get(String key){
        return variableList.get(key);
    }


}

public class Variable {

    private String value;
    private String name;

    public Variable(String aName, String aValue){
        name = aName;
        value = aValue;
    }

    public String getValue(){
        return value;
    }

    public String getName(){
        return name;
    }

    public void setValue(String aValue){
        value = aValue;
    }
}

This is obviously an extremely simple example, but I would like to accomplish something similar to this where I can get a variables window, set a breakpoint, and have a "debugger" list out my active scope objects and the variable objects inside.

I've been trying to read and understand: http://www.eclipse.org/articles/Article-Debugger/how-to.html

and its pretty dense (as well as extremely outdated), but I will try to take some time to understand it. I just wanted to see if anyone had any high level recommendations on how to approach this type of problem, as I have little experience developing plugins in eclipse or making debuggers.

Thanks!

Answer 1

Not an easy task. That article is still the main reference, I think. Old, but not outdated. Try to digest it, and preferably to make it work. Before it, you should have a minimal experience developing Eclipse plugins.

There are many pieces in the picture, but the first thing you must understand is that when Eclipse is debugging something (assuming we are using the standard debug model), we have two separate "worlds": the Eclipse side, and the interpreter side (or, if you prefer, the "local" and "remote" sides).

Int the Eclipse side, the programming involves a cooperation between some Eclipse core classes and some classes of your own, which extend or implement some Eclipse classes/interfaces:

• A "launchConfigurationType" (extension point in your plugin.xml) which causes the apparition of a new custom configuration when you click "Debug As -> New Configuration); this goes togetther with some "launchConfigurationTabGroups" definition that defines the "Tabs" dialogs that will appear in your custom launch configuration (eg) (each Tab will have its own class typically).

• The launchConfigurationType is typically associated to a LaunchDelegate class, which is sort of your bootstrap class: it has the responsability of creating and starting a running/debugging instance, both on the Eclipse side and on the "interpreter" (or "remote") side.

• On the Eclipse side, the running/debugging instance is represented by a IDebugTarget object and its children (the implementation is your responsability); this is created by the LaunchDelegate and "attached" to the remotely running process at launching time.

• The remote side, the interpreter or program you are actually debugging, can be anything: a binary executable, a perl script, some app running in a some site (perhaps also a local Java program; but, even in this case, this would probably run in its own JVM, not in the debugging Eclipse JVM!). Your IDebugTarget object must know how to communicate to the "remote interpreter" (eg, by TCP) and perform the typical debugger tasks (place breakpoints, step, run, ask for variables, etc) - but the protocol here is up to you, it's entirely arbitrary.

• What is not arbitrary is the hierarchy of your custom classes that the running Eclipse debugger will use: these should have a IDebugTarget as root, and should implement "The debug model" (see figure in article). As said above, the IDebugTarget object is who understands how to make the translation between the EClipse side and the remote side (see this image)