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<div class=Section1>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Bringing back those concepts would be a great boost to Smalltalk
in general.<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'>Sean<o:p></o:p></span></p>
<p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";
color:#1F497D'><o:p> </o:p></span></p>
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<div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0cm 0cm 0cm'>
<p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span
style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>
squeak-dev-bounces@lists.squeakfoundation.org [mailto:squeak-dev-bounces@lists.squeakfoundation.org]
<b>On Behalf Of </b>john<br>
<b>Sent:</b> Friday, January 22, 2010 8:50 PM<br>
<b>To:</b> The general-purpose Squeak developers list<br>
<b>Subject:</b> Re: [squeak-dev] Smalltalk vs Eclipse<o:p></o:p></span></p>
</div>
</div>
<p class=MsoNormal><o:p> </o:p></p>
<p class=MsoNormal>Actually, Firewall depended upon the complete separation of
program under development from development environment. The small executable
work was follow on to show that one could, for example, implement the unix
command mv and deploy an optimized 24k image. Needless to say, it loaded and
ran very fast.<o:p></o:p></p>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal>Much of this work was predicated upon the Package, Cluster,
Subsystem, Program model used by Team/V. Packages, Clusters, Subsystems and
Programs were subclasses of Scoped Module. A Subsystem was an aggregation of
Packages (identified by a top level cluster) that defined a complete namespace
once reconciled with its import list. A program was a collection of Subsystems
whose imports transitively closed. The development environment would open a
system browser upon a top level Program. That program could be the development
environment itself, or a program under development. Firewall included the
capability of allowing the program under development to be a distinct process
reachable through a socket. Dale Heinreichs of Metacello fame, was a key
developer on the Cascade toolset that implemented all this functionality and
more in the buried Jigsaw project.<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal>Putting the core connectivity to a Program in the vm solved
the bootstrap problem. The problem relates to debugging a program that has only
the necessary runtime artifacts, but not the semantic model from which it was
compiled. Once connected, remote compilers, debuggers, browsers and workspaces
could load the corresponding program model and do their work through a very
minimal compiled in connection interface.<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal>From the very beginnings of Team/V, the development tools
acted only upon the semantic model, not the classes and methods themselves. Due
to corporate pressure to hide certain sections of code, most developers never
new they had full support for Namespaces via Subsystems, or that their
development image was modeled as a Program.<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal>Sigh.<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal>John Sarkela :-}><o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><o:p> </o:p></p>
<div>
<div>
<p class=MsoNormal>On Jan 22, 2010, at 1:04 PM, Eliot Miranda wrote:<o:p></o:p></p>
</div>
<p class=MsoNormal><br>
<br>
<o:p></o:p></p>
<p class=MsoNormal style='margin-bottom:12.0pt'>Hi Ralph,<o:p></o:p></p>
<div>
<p class=MsoNormal>On Thu, Jan 21, 2010 at 10:40 PM, Ralph Boland <<a
href="mailto:rpboland@gmail.com">rpboland@gmail.com</a>> wrote:<o:p></o:p></p>
<p class=MsoNormal>Lest I confuse you let me state that I STRONGLY prefer using
the<br>
Smalltalk (Squeak in my case) development environment to using<br>
Eclipse. It is also worth pointing out that Eclipse is a development<br>
environment that works with multiple languages whereas in<br>
Smalltalk the development tool and development language are<br>
intimately connected so to compare the two is to compare apples<br>
and oranges.<br>
<br>
Nevertheless there are advantages to both and I wonder to what<br>
extent I can have my cake and eat it too (that would be an orapple<br>
cake I suppose). I should also point out that my discussion is abstract;<br>
I am asking if it would have been better if Smalltalk had<br>
been designed the way I propose and not should some Smalltalk,<br>
say Squeak, now be modified to be so.<br>
<br>
The thing, particular to this discussion, about Eclipse that I like<br>
is that the Eclipse (image I will call it) is separate from the<br>
application (image I will call it). In Smalltalk the two images are<br>
combined. This means that a lot of code is encorporated<br>
into your application image that you may not want.<br>
Of course, before you release your application you can run a<br>
stripping program or process that strips out code that is not<br>
used in your application. (I have never done this but my<br>
understanding is that this is possible.)<br>
<br>
Never having done this I assume that stripping is not that<br>
satisfactory because there is much code that cannot be<br>
stripped out; certainly unused methods and likely unused<br>
classes as well; the dynamic nature of Smalltalk means that<br>
much necessary information to determine that a method or<br>
class is not used is not available so such methods and classes<br>
must be included in the application release.<br>
Some may argue, that with all the memory processing power<br>
available today, who cares; but I care. For example, I would<br>
like to be able to put a Smalltalk application into a linux pipe<br>
as in:<br>
<br>
a | b > c<br>
<br>
where a or b or both are applications written in Smalltalk.<br>
Similarly I would like to use Smalltalk applications in bash (Linux)<br>
shells scripts or use it in other scripting languages. So it<br>
may be important that my image not be unnecessarily<br>
large as getting it started may take longer than what it<br>
does once it is started.<br>
Of course I could use GNU Smalltalk for this but is it really<br>
necessary that I know/use two smalltalks?<br>
<br>
I think the Eclipse model suggests an improvement to Smalltalk.<br>
It seems to me that when you run Smalltalk ideally you would<br>
run two images. One would be the development environment image<br>
and the other would be the application image. When you started<br>
a new project you would choose from a selection of start images<br>
each including some subset of the development classes you<br>
expect to need. There would also be a capability to copy entire<br>
methods/classes/applications/other from the development image to the<br>
application image. Note that in this model there would be need to search<br>
the code base of either image (or both). For example, I may want
to find<br>
implementors/senders of method #doSomething in the development
image,<br>
the application image, or both. I think being able to search the
application<br>
code base only is especially useful.<br>
<br>
An interesting example is if you were working on the development image<br>
itself. In this case you would of course make as your application a copy<br>
of the development image (and its changes file). Now, in principle you
need<br>
not worry about many of the situations in which you get into an infinite loop<br>
because you have broken the development environment itself in some way<br>
such as putting a halt message somewhere that get called every time the<br>
debugger is called.<br>
Yes, but what if your are modifying the debugger itself? Well you need
some<br>
kind of command such as:<br>
<br>
#runAsDevelopmentEnvironmentOn: image changesFile: file
"A<br>
metacircular interpreter anybody?"<br>
<br>
I am not sure who this message is sent to.<br>
<br>
I am not actually sure if this is a good idea either. Perhaps if you<br>
want to work on the development<br>
environment you start your image with a special flag or simply no<br>
application image.<br>
The development image then becomes editable and there is no<br>
application image; The<br>
development image and application image become one as is the situation now.<br>
<br>
There are doubtless many problems I am not seeing here and even<br>
many ways this may be a good idea that I have not considered.<br>
<br>
Either way I would like to hear what they are.<br>
<br>
How much of an effort would be involved in modifying some version<br>
of Smalltalk (say Squeak) to work this way? (I have NO plans to do
this!)<br>
<br>
How much of a benefit would such a version of Smalltalk really be?<br>
<br>
Has this been done before, perhaps in some other language, and what<br>
were the results?<o:p></o:p></p>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal>I can't speak in detail to the Firewall work done at
Digitalk by people like Steve Messick, but they did get stuff done in the late
90's, although I don't think anything was productised. I think they made
the mistake of focussing on being able to produce very small executables rather
than just separating the development and deployment images. I think Steve
was able to produce a tiny executable that only contained SmallInteger and
hence was able to eliminate tagged pointers and method lookup. But the
focus on optimization was I think a step too far. One thing I remember
was that the communications stub in the deployment image was in the VM, not in
Smalltalk code, again I think a mistake. Can anyone from Digitalk put flesh on
these bones?<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal>We spent a lot of time discussing doing this in the
VisualWorks team about 10 years ago but as far as I'm aware none of it was
realised. Splitting tools UIs from the image under development (the
target image) was a major design goal behind OpenTalk, the distributed
messaging framework that Xu Wang did. We had the idea of the Model in an
MVC triad being the interface between the UI and target images, the natural
point at which one would define an API narrow enough to be efficiently
distributed. If the API is designed appropriately one would be exchanging
symbols (class names, selectors etc) not complex objects (classes, compiled
methods) and that because symbols and numbers are immutable they can be passed
by value.<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal>We had the idea of the model being split in two, one half
being specific to a tool and the same whether one was in a single image or in
the ui/target pair, and the other half being an adaptor to either the local
image or the remote target. This adaptor would have sat between a model
and some complex object graph (like the class hierarchy) and defined the entire
API through which the object graph was accessed, narrowing the interface to
make it suitable for distribution, and doumenting the interface to make it
easier to understand. Vassili named these things between the model and an
object graph TTIBs for "The Things In Between".<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal>We very much wanted to produce a set of tools in a tools UI
image that could be targetted either at itself or at a remote target, and
wanted to be able to attach the tools image to a remote target dynamically
(which we called "dynamic capitation", for dynamically gaining a
head) so that one could have full debuggability on a remote image deployed in
the field. Alas we never managed to get the priority of the project high
enough to actually commit major resources to it. There were always more
pressing more mundane things to do. Frustration at not doing things like
this was in part behind my leaving Cincom. Xu got quite far with a
prototype, demonstrating things like a distributed inspector that allowed one
to walk though an object graph spanning more than one image. The
inspector would change colour to indicate which machine the current object was
one.<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal>Personally I think that Smalltalk is the ideal vehicle for
this kind of approach. We have lightweight remote messaging which is
relatively easy to implement. We have UI architectures which are
relatively well-decomposed and amenable to distribution. We have a
reified exception system which is not pushed down into hidden execution
machinery and which has resume semantics. We now have a much faster much
more reliable internet. We could relatively easily add things like
delegation which can enable interesting interleaving of tools and target images
(see below). I think we could have something truly revolutionary, the
ability to interact with a remote headless image that contains no development
tools or UI frameworks and only a relatively small communications module
(remote messaging interface). This would enable us to get to images of a
few 10s or 100s of kilobytes. I fervently hope you work on this.
Lots of people want this. I was reading Colin's <a
href="http://www.wiresong.ca/air/">Thin Air</a> pages on wiresong yesterday and
what he wants is realised by this.<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal>If you do work on this remember your goals. The most
important thing is incremental deliverables and useful progress. Don't
focus on whizzy optimisations or cool demos (such as the inspector changing
colour). Dn't focus on arbitrarily complex topologies of remote images. Instead
focus on building a robust, well-engineered remote tools framework that just
allows one to do what one can do today in a browser and debugger, but remotely
between two images. I would start with browser, debugger and stripper,
where stripper would be something that allowed you to eliminate code from the
target image using the UI image to discover what was there and what was needed
or not, i.e. remote stripping, not the much trickier auto-stripping.<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal>On delegation I think one really cool thing is to wrap
remote objects with local development-only code. In a deployed image I
would expect there to be no inspectorClass methods or debugPrintOn: messages
etc. The target is lean and mean. Anything not needed for
deployment except that which supports adequate remote messaging is absent.
So one wants to be able to add methods that add debugging features to
remote objects, and delegation is the way. If the local handle on a
remote object is wrapped by a delegate, the delegate can implement the
debugging methods. Catching doesNotUnderstand: in the target mage can
allow one to intercept computations in the target and resume them in the
development image. So when connecting a tools image to a target one would
layer tools and UI code upon objects in the target but that code would reside
only in the tools image.<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal>Naming conventions in packaging, like splitting a Foo
package into Foo-Deployment & Foo-Development could help in making this
kind of split easy to navigate and conceptualise. So after producing the
tools/target split I would next focus on packaging tools, including analysis of
call graphs etc to help automating the deployment/development split.<o:p></o:p></p>
</div>
<div>
<p class=MsoNormal><o:p> </o:p></p>
</div>
<div>
<p class=MsoNormal>Anyway, enough waffle. It's great to hear this idea
again. Go for it!<o:p></o:p></p>
</div>
<blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0cm 0cm 0cm 6.0pt;
margin-left:4.8pt;margin-right:0cm'>
<p class=MsoNormal style='margin-bottom:12.0pt'><br>
(Constructive) comments most welcome.<br>
<br>
Regards,<br>
<span style='color:#888888'><br>
Ralph Boland</span><o:p></o:p></p>
</blockquote>
</div>
<p class=MsoNormal style='margin-bottom:12.0pt'><o:p> </o:p></p>
</div>
<p class=MsoNormal><o:p> </o:p></p>
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