Web Debug Protocols Comparison

[mcollins]

Since Opera's Scope protocol has now been announced, I wanted to
understand how it compared to V8 and DBGP for Web debugging, so I
tried to put together a quick comparison of features, which I've
uploaded here:

http://spreadsheets.google.com/ccc?key=tHjhsEJWVzXUR_Ix7wvTNBQ

First impressions are that Scope has much more complete support for
the whole Web runtime debugging, which includes CSS/DOM inspection,
and console logging service. Scope's event model also seems more
thorough than the others. V8's debugger protocol seems to have the
most functionality for pure javascript debugging, but obviously lacks
any features for other aspects of Web debugging. DBGP is a lowest-
common-denominator protocol, but still has some interesting features
that are not present in either Scope or V8, most notably the ability
for a client to get/list breakpoints from the debug engine.

mc

[David Storey]

I asked on our list regarding the "?" in the spreadsheet for step
into, etc:

"we are lacking comments in the message definitions, for ThreadMode
it
should be:

command ContinueThread(ThreadMode) returns Default = 2;

message ThreadMode
{
required uint32 runtimeID = 1;
required uint32 threadID = 2;
// on of "run", "step-into-call", "step-next-line", "step-out-of-
call"
required string mode = 3;
}
"
Hopefully that helps? If you have any questions please let me know.

[Mike Collins]

Thanks David, I assumed that Scope had the ability to do stepping, since dragonfly does it, just didn't see it in the docs, hence the '?'.

I am curious as to the reasons behind the implementation details though. DBGP implements step into/out/over as separate commands, Scope and V8 as arguments to a 'continue' command.  Not sure if the difference is technical or just a stylistic one.

mc

[Attila Szegedi]

On 2009.07.08., at 2:19, Mike Collins wrote:

> DBGP implements step into/out/over as separate commands, Scope and
> V8 as arguments to a 'continue' command. Not sure if the difference
> is technical or just a stylistic one.

Stylistic.

Attila.