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From hu jing <huj....@gmail.com>
Subject Re: [GSoC] Proposal For jdb command line debugger tool.
Date Thu, 02 Apr 2009 12:55:35 GMT
Thank for your suggestion.We hava decided to using JDI to implement the
command line debugger.

2009/4/2 Oliver Deakin <oliver.deakin@googlemail.com>

> I see your point about performance, and of course the proposal is yours :)
> However I would put forward the following arguments in favour of using Java
> and JDI:
> - JDI is _the_ spec'ed public API for Java debugging, JDWP only describes
> the protocol. To write a jdb tool that uses JDWP directly sounds a lot like
> you will end up rewriting JDI in C code before actually writing the jdb
> tool, and that is not the remit for the project. Rewriting an API that
> already exists in Java (and is supported by another project - Eclipse) does
> not sound like a good idea.
> - JDI provides a solid spec to code to. You can take a JDI based agent to
> another Java runtime and it should work, so any additional function you add
> to the new jdb tool will immediately be available to use on all runtimes by
> launching your tool on that runtime.
> - I would argue that performance for a command line debugger is not a major
> issue. In a GUI environment, where multiple stack traces, variable displays
> and other data are being refreshed regularly, performance would be more
> important. However, in the simplified command line environment the need for
> super-fast processing of packets becomes a non-issue as there is so much
> less going on simultaneously.
> - A Java based tool is a lot more portable and easier to maintain. We also
> already have an intelligent launcher setup in Harmony which will
> automatically launch your executable Java class for a tool, so going down
> the Java route will fit neatly into the tools design we already have in the
> project.
> I hope you can see my point about JDWP vs. JDI for this tool. Good luck
> writing the proposal - don't forget the deadline is tomorrow!
> Regards,
> Oliver
> WenDong Zhang wrote:
>> Hi Oliver:
>> We did consider implementing this tool based on JDI, we have a
>> misunderstanding on between C/C++'s efficiency and Java's usability
>> for this project. We considered the implementation too extremely,
>> there is a long chain from JVMTI to JDB: JVMTI - JDWP - JDI - JDB.
>> JDI encapsulate JDWP and we don't need to care about the protocol
>> detail: command, package, data type and so on. Maybe we should use the
>> software architecture's principle: add a midware to our implements to
>> decouple the dependence and more transparent to users even it may
>> cause a few of efficient problems.
>> 2009/4/1 Oliver Deakin <oliver.deakin@googlemail.com>:
>>> Hi, and welcome to Harmony!
>>> hu jing wrote:
>>>> Hi all,
>>>>   I am interested in the "jdb command line debugger tool". I find Sun
>>>> jdb
>>> Great!
>>>> is not very friendly to developers. I want to add some useful function
>>>> to
>>>> this tool. Such as, Auto-complete command line, smart format for the
>>>> user
>>>> input. And we can also supply some interfaces to further development.
>>>>   Wen Dong(zwd2005@gmail.com) and I want to participate in this tool
>>>> development. We are from the same laboratory of the Department of
>>>> Computer
>>>> Science of Nanjing University. We worked together for two years and now
>>>> we
>>>> are both interns in IBM CDL. I think we can work out the debugger tool
>>>> pretty.
>>> I don't know what the rules are for co-working on a project - I believe
>>> each
>>> project has to be an individual effort. You could ask on the GSoC
>>> discussion
>>> mailing list (mailing lists and other useful info can be found here [1]).
>>>>   The popular architecture is JPDA(Java Platform Debugger Architecture).
>>>> JPDA contains three parts: JVMTI, JDWP and JDI. JVMTI(Java Virtual
>>>> Machine
>>>> Tool Interface) supply a set of native interface supplied by JVM. The
>>>> development based on the JVMTI level is complex and hard to be extended
>>>> and
>>>> modified. JDWP supplies a standard protocol for the communication
>>>> between
>>>> the debugger and debuggee. And it also provides the socket interface.
>>>> JDI
>>>> is
>>>> debug interface. It is mostly implemented in Java. JVMTI and JDWP are
>>>> based
>>>> native code. We want to implement the java command line debugger tool in
>>>> C/C++ considering efficiency. We will use JDWP interface for development
>>>> efficiency and Portability.
>>> Have you considered coding the tool in Java and using JDI to access all
>>> the
>>> required functions? I think it will be more portable, easier to maintain,
>>> and will fit more naturally with the other command line tools we have in
>>> Harmony.
>>>>   The following is our main idea for this tool:
>>>>   1.format the user input.
>>>>   2.validate the command arguments.
>>>>   3.Create connection between debugger and JVM, and here we can use the
>>>> JDWP Transport Interface. Based on the JDWP, We create packages
>>>> containing
>>>> the command information and send packages to JVM by using the transport
>>>> interface. JVM will process these packages and send the feedback to the
>>>> debugger. And we will process this information.
>>>>   4.print the message on the console.
>>>> Schedule:
>>>>      We can work 20 hours each week.
>>>>      April 4 ~ April 30: Be family with JDWP and JDWP Transport
>>>> Interface.
>>>>      May 1 ~ May 22: meet our mentors, read the documentation and get
>>>> some
>>>> suggestions from our mentors.
>>>>      May 23 ~ May 30: to determine the final framework and algorithm
>>>> details, divide the work with my partners.
>>>>      June 1 ~ June 30: coding.
>>>>      July 1 ~ July 5: integration, test and debug for mid-term
>>>> evaluations.
>>>>      July 6 ~ August 11: process the debug, documentation and
>>>> integration.
>>>>      August 12 ~ August 24: write test unit, debug and final release.
>>> Looks like a good plan. You need to clear up the issue of working with a
>>> partner - if that is a possibility, or you can decide on one of you to
>>> work
>>> on the project alone, then please draft a submission in the GSoC tool [2]
>>> as
>>> soon as possible. The deadline for submissions is Friday 3rd April.
>>> Regards,
>>> Oliver
>>> [1]
>>> http://socghop.appspot.com/document/show/program/google/gsoc2009/faqs
>>> [2] http://socghop.appspot.com/
>>>> Jing Hu , WenDong Zhang.
>>> --
>>> Oliver Deakin
>>> Unless stated otherwise above:
>>> IBM United Kingdom Limited - Registered in England and Wales with number
>>> 741598. Registered office: PO Box 41, North Harbour, Portsmouth,
>>> Hampshire
>>> PO6 3AU
> --
> Oliver Deakin
> Unless stated otherwise above:
> IBM United Kingdom Limited - Registered in England and Wales with number
> 741598. Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire
> PO6 3AU

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