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Robert Tolksdorf wrote:
<p>I was not able to open your dSelf documents?
<p>What jar means? Is it ps, pdf, doc. What is it?
<br>I work in a Sun station/.
<p>[being new to the list, I am not sure about conventions - if this
<br>should be answered directly, please tell]
<p>Jecel Assumpcao Jr
<br>> Wow! Congratulations on this excelent work!
<br>> At a presentation I gave on Monday I was asked if any academic groups
<br>> were working on Self implementations and I said "no". I am very glad
<br>> that I was wrong about that.
<br>> After reading the dself.pdf I would like to make some slight
<br>> corrections. There were, in fact, previous papers on distributed
<br>> but they were written in Portuguese and so wouldn't have been of
<br>> help to you. My key insight in the later papers was that not only
<br>> primitive objects but any immutable objects could be copied without
<br>> affecting the execution semantics. My system is a multiuser one and
<br>> any given "session" most objects (those belonging to other users)
<br>> read-only and can be replicated instead of using remote references.
<p>Have you tried to push the papers through the Altavista Babelfish?
<p>Concerning replication: Right now, there are two sorts of things in
<br>dSelf, the one are references, the others are primitive objects (such
<br>as the number 1). The primtive objects are located at _every_ dSelf
<br>VM, so in some sense, they are in fact replicas (one can also say that
<br>eg. the Java-standard classes are replicated on every JVM). Of course,
<br>true replica need some sort of consistency management, which we
<br>currently do not need, as primitve objects are immutable (cf. the java
<br>standard classes). There is going to be another diploma theses that
<br>deals with the issue. In fact, the work on it should start this week.
<p>My view is that we should introduce something like in Replicated Obliq
<br>by MacIntyre, where remote, replicated and simple (ie. primitive)
<br>objects are distinguished and the environment offers means to change
<br>the "class" of objects along those three kinds.
<br>> Your use of "<-" versus "=" in slot declarations seems strange.
<br>> think that the stack examples are quite right: you change slots defined
<br>> with "=" ("parent", for example). You use the "clone" method but
<br>> not defined anywhere (you don't mention the traditional "traits
<br>> clonable" object, for example).
<p>we should have mentioned (and might add a footnote), that these
<br>examples use a pseudo code. The reason for that was to show simple
<br>code instead of lots of _addslots messages whose explanation would
<br>have cluttered the flow of the text.
<br>> Several of the things you mention as missing in dSelf were actually
<br>> dropped in Self 3.0. I found it strange that you wrote that Self
<br>> doesn't have local methods, but I just tried it in Self 4.1.2 and
<br>> indeed get the error: "syntax error - local slots not implemented
<br>> How strange.
<p>We took 4.x as reference. The assumption of downward compatibilty
<br>seems to be quite wrong...
<br>> In tinySelf 1 I explored parallel (but not distributed) execution
<br>> Self but got stuck in trying to lock things automatically. It is
<br>> easy problem to solve.
<p>We currently have this ad-hoc solution with locking objects. The
<br>mentioned diploma-thesis shall also deal with the issue of finding
<br>suited model for concurrency in self and implementing it. in dSelf,
<br>have implicitly concurrency by two people (or a shell) starting two
<br>dself-VMs that then do run concurrently, although there is no forking
<br>within a dself vm.
<br>> Once again: good work!
<p>Thanks. [I include Kai in the cc, as he did the implementation and a
<br>lot of design decisions]
<p>> -- Jecel
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<br>Dr.-Ing. Robert Tolksdorf
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