Indeed -- what other self papers would you recommend? -- Dave Paola
On Mar 13, 2013, at 6:52 PM, Casey Ransberger <[email protected]> wrote: > Actually that paper answered a lot of questions I had about stuff that I want > to be able to do in Squeak eventually. I thought I'd read all of the Self > papers, but it looks like I missed this one. Thanks for the question, Dave, > and thanks for the answer, Robert! > > On Wed, Mar 13, 2013 at 3:45 PM, David Paola <[email protected]> wrote: > Thanks both of you for your answers :-) that self paper is *exactly* what I > am looking for. > > Happy hacking! > > -- > Dave Paola > > On Mar 12, 2013, at 6:47 PM, Robert Krahn <[email protected]> wrote: > >> Btw. the most influencing work for Lively's persistency mechanism comes from >> Self, see the excellent paper Annotating Objects for Transport to Other >> Worlds, >> >> >> On Tue, Mar 12, 2013 at 5:34 PM, Robert Krahn <[email protected]> wrote: >> Hi, Dave -- >> >> Thanks for the question, this is actually a really fascinating topic :) >> >> First, we wrote up some general information about it (that let's you >> interactively try out things ;) here: >> http://lively-kernel.org/repository/webwerkstatt/documentation/Serialization-Overview.xhtml >> and here: >> http://lively-kernel.org/repository/webwerkstatt/documentation/Serialization-Interface.xhtml >> >> I guess the "hairy" part was/is how to deal with "native" objects. JS browser >> environments introduce functions and state that are not implemented / >> represented in the JS context but hidden. The DOM and DOM nodes are an >> example >> for that -- you cannot get or modify all the state that would be necessary to >> capture or restablish a document / world. >> >> The solution that we came up with and that works very well is to implement a >> general JS serializer that walks an object graph starting from root objects. >> When certain objects are encountered - e.g. DOM nodes - we make an exception >> (this is what the serialization plugins that are mentioned in the worlds >> above >> are for) and store not their full object representation but just "what we >> need >> to know". >> >> The creation of objects from a serialization works accordingly >> create/instantiate objects + run custom init code for the "exceptions". >> >> The shortcomings of this approach are the following: >> - On the application development level you still need to be a bit careful >> what >> objects you reference. Direct pointers to DOM nodes for example won't break >> the serialization but when you deserialize you need custom init logic to >> make things work as expected again. >> - The stored representations become big (x-xxx MBs) really quickly. >> Implementing optimizations using the plugin approach is possible but >> requires additional work. >> >> This deals with the "state" of a JS application / Lively world. Another point >> that you mention is to capture running computations. From a certain level of >> abstraction this is actually the same thing but since JS has incomplete >> metprogramming capabilities (you are not able to reflect on closures, e.g.) >> the "hidden state" problem comes up again. For Lively practically this has >> little impact since in the "reactive" browser environment Lively don't have >> to >> implement a "main" function. Anyway, we dealt with the problem and came up >> with a solution. I will describe that in an upcoming post. >> >> Please let me know if you have questions or want a more technical answer. >> >> Best, >> Robert >> >> >> >> On Mon, Mar 11, 2013 at 5:51 PM, David Paola <[email protected]> wrote: >> Hi lively kernel folks, >> >> I've spent the past month or so digging around in several language VMs -- >> CPython, Rubinius, Topaz, Pypy, etc in an attempt to add the equivalent of >> the original Smalltalk "snapshot" VM primitive. Obviously I have been naive. >> >> I've learned a lot, above all else that I'm not giving up. I have a decent, >> academic understanding of compilers, interpreters, VMs (and a foggy >> understanding of JITs), and was curious if anyone could clarify how the >> lively kernel serializes the world into JSON. Was this hairy? What were the >> hardest parts? >> >> I realize everyone has a full time job and can't hand-hold a newbie, so any >> direction at all would be appreciated. I tried to pick apart the Squeak >> source code but without a background in the Squeak architecture, it was >> fruitless. >> >> Thanks so much for your energy on lively kernel, I'm looking forward to >> hearing more and possibly contributing in the future. >> >> -dave >> >> More info: >> >> I realize that the "high level" idea of snapshotting a running VM basically >> involves serializing the object memory, bytecode, and instruction pointer, >> and then deserializing that on "resume". Most of the issues I'm encountering >> lead me to believe I have an incomplete understanding. >> >> -- >> Dave Paola >> >> _______________________________________________ >> lively-kernel mailing list >> [email protected] >> http://lists.hpi.uni-potsdam.de/listinfo/lively-kernel >> >> > > > _______________________________________________ > lively-kernel mailing list > [email protected] > http://lists.hpi.uni-potsdam.de/listinfo/lively-kernel > > > _______________________________________________ > lively-kernel mailing list > [email protected] > http://lists.hpi.uni-potsdam.de/listinfo/lively-kernel
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