Re: [friam] Classification of actor languages

"Mark S. Miller" <[email protected]> Mon, 16 Feb 2015 17:11:53 -0800
Newsgroups gmane.comp.lang.e.general
Message-ID <CABHxS9gu2ouaORNAnOB_nTLrJ_vec5kPaNHp94xyjDGXuX-Rag@mail.gmail.com>
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The security of actors that we have previously discussed derives from the
locality laws. Do types somehow relate to the locality laws? If not, are we
talking about a distinct set of security properties?


On Mon, Feb 16, 2015 at 1:44 PM, Carl Hewitt <[email protected]> wrote:

>  Actors need types in order to be able to securely send messages.
>
>
>
> Cheers,
>
> Carl
>
>
>
> *From:* friam-/[email protected] [mailto:friam-/[email protected]]
> *Sent:* Monday, February 16, 2015 12:50
>
> *To:* friam
> *Cc:* Discussion of E and other capability languages
> *Subject:* Re: [friam] Classification of actor languages
>
>
>
> It is not at all obvious to me what you even mean by these terms. Can you
> define them in terms of, for example, the Hewitt-Baker Actor laws, the
> Clinger Actor semantics, or something equally foundational?
>
>
>
> As for conventional use of these terms, they mean many subtly different
> things in different contexts, so it is again not obvious precisely what y=
ou
> even intend to mean. For example, the main context I would expect to borr=
ow
> from, Java and C#, you explicitly say do not mean the same thing as you b=
y
> "interface".
>
>
>
>
>
>
>
>
>
>
>
> On Mon, Feb 16, 2015 at 12:46 PM, Carl Hewitt <[email protected]> wrote:
>
>   Hi Mark,
>
>
>
> It is obvious that an Actor needs to be able to implement multiple
> interfaces.
>
> However, it is important to avoid mistakes that were made in Java and C#.
>
> For example,
>
> =C2=B7       It must be possible to have the **same** message receiver
> signature in
>
> two different interfaces implemented by the same Actor.
>
> =C2=B7       It must not be possible **externally** to cast an address fo=
r one
> interface
>
> to an address for another interface.
>
>
>
> Cheers,
>
> Carl
>
>
>
> *From:* friam-/[email protected] [mailto:friam-/[email protected]]
> *Sent:* Monday, February 16, 2015 12:38
> *To:* friam
>
>
> *Cc:* Discussion of E and other capability languages
> *Subject:* Re: [friam] Classification of actor languages
>
>
>
> Carl, what do you mean by "interface" here? It doesn't sound like any
> foundational concept I know of from my long study of Actors.
>
>
>
>
>
>
>
> On Mon, Feb 16, 2015 at 12:34 PM, Carl Hewitt <[email protected]> wrote:
>
>   Hi Tom,
>
>
>
> It should **not** be the case that having an address for
>
> an interface to an Actor automatically enables sending messages
>
> to other interfaces of the Actor. The only way to obtain
>
> addresses for other interfaces is for them to be communicated
>
> in messages by the Actor.
>
>
>
> In this respect, Java and C# are **not** proper Actor programming
> languages
>
> because it is possible to **externally** cast from one interface of an
> Actor to another :-(
>
>
>
> Cheers,
>
> Carl
>
>
>
>
>
> *From:* friam-/[email protected] [mailto:friam-/[email protected]] *On Behalf
> Of *Tom Van Cutsem
> *Sent:* Monday, February 16, 2015 12:24
> *To:* friam-/[email protected]
> *Cc:* Discussion of E and other capability languages
> *Subject:* Re: [friam] Classification of actor languages
>
>
>
> Hi Carl,
>
>
>
> 2015-02-14 1:19 GMT+01:00 Carl Hewitt <[email protected]>:
>
>   Of course, an Actor can implement multiple interfaces.
>
>
>
> I am wondering how a =E2=80=9Cfacet=E2=80=9D relates to an interface.
>
>
>
> Indeed, an actor can implement multiple interfaces, but this typically
> means that anyone having a reference to the actor can send any message fr=
om
> the union of all interface methods. By contrast, in a vat with multiple
> facets, a reference to a facet provides access to only the methods expose=
d
> by that facet. Thus, facets make it easier to restrict authority.
>
>
>
> Of course, one could encode facets in a pure actor model, by passing a
> token designating the facet as part of the message. The actor can be
> programmed to dispatch the message to an internal object only if the toke=
n
> matches. But this would be an encoding of the vat model in a pure actor
> model.
>
>
>
> Cheers,
>
> Tom
>
> --
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>
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>
>
> --
>
>     Cheers,
>     --MarkM
>
> --
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> You received this message because you are subscribed to the Google Groups
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>
>
>
>
> --
>
>     Cheers,
>     --MarkM
>
> --
> You received this message because you are subscribed to the Google Groups
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> To unsubscribe from this group and stop receiving emails from it, send an
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> --
> You received this message because you are subscribed to the Google Groups
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--=20
    Cheers,
    --MarkM

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<div dir=3D"ltr">The security of actors that we have previously discussed d=
erives from the locality laws. Do types somehow relate to the locality laws=
? If not, are we talking about a distinct set of security properties?<div><=
br></div></div><div class=3D"gmail_extra"><br><div class=3D"gmail_quote">On=
 Mon, Feb 16, 2015 at 1:44 PM, Carl Hewitt <span dir=3D"ltr">&lt;<a href=3D=
"mailto:[email protected]" target=3D"_blank">[email protected]</a>&gt;</s=
pan> wrote:<br><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex=
;border-left:1px #ccc solid;padding-left:1ex">





<div lang=3D"EN-US" link=3D"blue" vlink=3D"purple">
<div>
<p class=3D"MsoNormal"><span style=3D"font-size:11.0pt;font-family:&quot;Mi=
crosoft Sans Serif&quot;,sans-serif;color:black">Actors need types in order=
 to be able to securely send messages.=C2=A0
<u></u><u></u></span></p>
<p class=3D"MsoNormal"><span style=3D"font-size:11.0pt;font-family:&quot;Mi=
crosoft Sans Serif&quot;,sans-serif;color:black"><u></u>=C2=A0<u></u></span=
></p>
<p class=3D"MsoNormal"><span style=3D"font-size:11.0pt;font-family:&quot;Mi=
crosoft Sans Serif&quot;,sans-serif;color:black">Cheers,<u></u><u></u></spa=
n></p>
<p class=3D"MsoNormal"><span style=3D"font-size:11.0pt;font-family:&quot;Mi=
crosoft Sans Serif&quot;,sans-serif;color:black">Carl<u></u><u></u></span><=
/p>
<p class=3D"MsoNormal"><span style=3D"font-size:11.0pt;font-family:&quot;Mi=
crosoft Sans Serif&quot;,sans-serif;color:black"><u></u>=C2=A0<u></u></span=
></p>
<p class=3D"MsoNormal" style=3D"margin-left:.5in"><b><span style=3D"font-si=
ze:11.0pt;font-family:&quot;Calibri&quot;,sans-serif">From:</span></b><span=
 style=3D"font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif"> <a =
href=3D"mailto:friam-/[email protected]" target=3D"_blank">friam@googlegroups=
.com</a> [mailto:<a href=3D"mailto:friam-/[email protected]" target=3D"_blank=
">friam-/[email protected]</a>]
<br>
<b>Sent:</b> Monday, February 16, 2015 12:50</span></p><div><div class=3D"h=
5"><br>
<b>To:</b> friam<br>
<b>Cc:</b> Discussion of E and other capability languages<br>
<b>Subject:</b> Re: [friam] Classification of actor languages<u></u><u></u>=
</div></div><p></p><div><div class=3D"h5">
<p class=3D"MsoNormal" style=3D"margin-left:.5in"><u></u>=C2=A0<u></u></p>
<div>
<p class=3D"MsoNormal" style=3D"margin-left:.5in">It is not at all obvious =
to me what you even mean by these terms. Can you define them in terms of, f=
or example, the Hewitt-Baker Actor laws, the Clinger Actor semantics, or so=
mething equally foundational?<u></u><u></u></p>
<div>
<p class=3D"MsoNormal" style=3D"margin-left:.5in"><u></u>=C2=A0<u></u></p>
</div>
<div>
<p class=3D"MsoNormal" style=3D"margin-left:.5in">As for conventional use o=
f these terms, they mean many subtly different things in different contexts=
, so it is again not obvious precisely what you even intend to mean. For ex=
ample, the main context I would expect
 to borrow from, Java and C#, you explicitly say do not mean the same thing=
 as you by &quot;interface&quot;.<u></u><u></u></p>
</div>
<div>
<p class=3D"MsoNormal" style=3D"margin-left:.5in"><u></u>=C2=A0<u></u></p>
</div>
<div>
<p class=3D"MsoNormal" style=3D"margin-left:.5in"><u></u>=C2=A0<u></u></p>
</div>
<div>
<p class=3D"MsoNormal" style=3D"margin-left:.5in"><u></u>=C2=A0<u></u></p>
</div>
<div>
<p class=3D"MsoNormal" style=3D"margin-left:.5in"><u></u>=C2=A0<u></u></p>
</div>
</div>
<div>
<p class=3D"MsoNormal" style=3D"margin-left:.5in"><u></u>=C2=A0<u></u></p>
<div>
<p class=3D"MsoNormal" style=3D"margin-left:.5in">On Mon, Feb 16, 2015 at 1=
2:46 PM, Carl Hewitt &lt;<a href=3D"mailto:[email protected]" target=3D"_b=
lank">[email protected]</a>&gt; wrote:<u></u><u></u></p>
<blockquote style=3D"border:none;border-left:solid #cccccc 1.0pt;padding:0i=
n 0in 0in 6.0pt;margin-left:4.8pt;margin-right:0in">
<div>
<div>
<p class=3D"MsoNormal" style=3D"margin-left:.5in">
<span style=3D"font-size:11.0pt;font-family:&quot;Microsoft Sans Serif&quot=
;,sans-serif;color:black">Hi Mark,</span><u></u><u></u></p>
<p class=3D"MsoNormal" style=3D"margin-left:.5in">
<span style=3D"font-size:11.0pt;font-family:&quot;Microsoft Sans Serif&quot=
;,sans-serif;color:black">=C2=A0</span><u></u><u></u></p>
<p class=3D"MsoNormal" style=3D"margin-left:.5in">
<span style=3D"font-size:11.0pt;font-family:&quot;Microsoft Sans Serif&quot=
;,sans-serif;color:black">It is obvious that an Actor needs to be able to i=
mplement multiple interfaces.</span><u></u><u></u></p>
<p class=3D"MsoNormal" style=3D"margin-left:.5in">
<span style=3D"font-size:11.0pt;font-family:&quot;Microsoft Sans Serif&quot=
;,sans-serif;color:black">However, it is important to avoid mistakes that w=
ere made in Java and C#.</span><u></u><u></u></p>
<p class=3D"MsoNormal" style=3D"margin-left:.5in">
<span style=3D"font-size:11.0pt;font-family:&quot;Microsoft Sans Serif&quot=
;,sans-serif;color:black">For example,</span><u></u><u></u></p>
<p style=3D"margin-left:.5in"><span style=3D"font-size:11.0pt;font-family:S=
ymbol;color:black">=C2=B7</span><span style=3D"font-size:7.0pt;color:black"=
>=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0
</span><span style=3D"font-size:11.0pt;font-family:&quot;Microsoft Sans Ser=
if&quot;,sans-serif;color:black">It must be possible to have the *<b>same</=
b>* message receiver signature in
</span><u></u><u></u></p>
<p style=3D"margin-left:.5in"><span style=3D"font-size:11.0pt;font-family:&=
quot;Microsoft Sans Serif&quot;,sans-serif;color:black">two different inter=
faces implemented by the same Actor.</span><u></u><u></u></p>
<p style=3D"margin-left:.5in"><span style=3D"font-size:11.0pt;font-family:S=
ymbol;color:black">=C2=B7</span><span style=3D"font-size:7.0pt;color:black"=
>=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0
</span><span style=3D"font-size:11.0pt;font-family:&quot;Microsoft Sans Ser=
if&quot;,sans-serif;color:black">It must not be possible *<b>externally</b>=
* to cast an address for one interface</span><u></u><u></u></p>
<p style=3D"margin-left:.5in"><span style=3D"font-size:11.0pt;font-family:&=
quot;Microsoft Sans Serif&quot;,sans-serif;color:black">to an address for a=
nother interface.</span><u></u><u></u></p>
<p class=3D"MsoNormal" style=3D"margin-left:.5in">
<span style=3D"font-size:11.0pt;font-family:&quot;Microsoft Sans Serif&quot=
;,sans-serif;color:black">=C2=A0</span><u></u><u></u></p>
<p class=3D"MsoNormal" style=3D"margin-left:.5in">
<span style=3D"font-size:11.0pt;font-family:&quot;Microsoft Sans Serif&quot=
;,sans-serif;color:black">Cheers,</span><u></u><u></u></p>
<p class=3D"MsoNormal" style=3D"margin-left:.5in">
<span style=3D"font-size:11.0pt;font-family:&quot;Microsoft Sans Serif&quot=
;,sans-serif;color:black">Carl</span><u></u><u></u></p>
<p class=3D"MsoNormal" style=3D"margin-left:.5in">
<span style=3D"font-size:11.0pt;font-family:&quot;Microsoft Sans Serif&quot=
;,sans-serif;color:black">=C2=A0</span><u></u><u></u></p>
<p class=3D"MsoNormal" style=3D"margin-left:1.0in">
<b><span style=3D"font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-ser=
if">From:</span></b><span style=3D"font-size:11.0pt;font-family:&quot;Calib=
ri&quot;,sans-serif">
<a href=3D"mailto:friam-/[email protected]" target=3D"_blank">friam@googlegro=
ups.com</a> [mailto:<a href=3D"mailto:friam-/[email protected]" target=3D"_bl=
ank">friam-/[email protected]</a>]
<br>
<b>Sent:</b> Monday, February 16, 2015 12:38<br>
<b>To:</b> friam</span><u></u><u></u></p>
<div>
<div>
<p class=3D"MsoNormal" style=3D"margin-left:.5in"><br>
<b>Cc:</b> Discussion of E and other capability languages<br>
<b>Subject:</b> Re: [friam] Classification of actor languages<u></u><u></u>=
</p>
</div>
</div>
<div>
<div>
<p class=3D"MsoNormal" style=3D"margin-left:1.0in">
=C2=A0<u></u><u></u></p>
<div>
<p class=3D"MsoNormal" style=3D"margin-left:1.0in">
Carl, what do you mean by &quot;interface&quot; here? It doesn&#39;t sound =
like any foundational concept I know of from my long study of Actors.<u></u=
><u></u></p>
<div>
<p class=3D"MsoNormal" style=3D"margin-left:1.0in">
=C2=A0<u></u><u></u></p>
</div>
<div>
<p class=3D"MsoNormal" style=3D"margin-left:1.0in">
=C2=A0<u></u><u></u></p>
</div>
</div>
<div>
<p class=3D"MsoNormal" style=3D"margin-left:1.0in">
=C2=A0<u></u><u></u></p>
<div>
<p class=3D"MsoNormal" style=3D"margin-left:1.0in">
On Mon, Feb 16, 2015 at 12:34 PM, Carl Hewitt &lt;<a href=3D"mailto:hewitt@=
irobust.org" target=3D"_blank">[email protected]</a>&gt; wrote:<u></u><u><=
/u></p>
<blockquote style=3D"border:none;border-left:solid #cccccc 1.0pt;padding:0i=
n 0in 0in 6.0pt;margin-left:4.8pt;margin-top:5.0pt;margin-right:0in;margin-=
bottom:5.0pt">
<div>
<div>
<p class=3D"MsoNormal" style=3D"margin-left:1.0in">
<span style=3D"font-size:11.0pt;font-family:&quot;Microsoft Sans Serif&quot=
;,sans-serif;color:black">Hi Tom,</span><u></u><u></u></p>
<p class=3D"MsoNormal" style=3D"margin-left:1.0in">
<span style=3D"font-size:11.0pt;font-family:&quot;Microsoft Sans Serif&quot=
;,sans-serif;color:black">=C2=A0</span><u></u><u></u></p>
<p class=3D"MsoNormal" style=3D"margin-left:1.0in">
<span style=3D"font-size:11.0pt;font-family:&quot;Microsoft Sans Serif&quot=
;,sans-serif;color:black">It should *<b>not</b>* be the case that having an=
 address for
</span><u></u><u></u></p>
<p class=3D"MsoNormal" style=3D"margin-left:1.0in">
<span style=3D"font-size:11.0pt;font-family:&quot;Microsoft Sans Serif&quot=
;,sans-serif;color:black">an interface to an Actor automatically enables se=
nding messages</span><u></u><u></u></p>
<p class=3D"MsoNormal" style=3D"margin-left:1.0in">
<span style=3D"font-size:11.0pt;font-family:&quot;Microsoft Sans Serif&quot=
;,sans-serif;color:black">to other interfaces of the Actor. The only way to=
 obtain</span><u></u><u></u></p>
<p class=3D"MsoNormal" style=3D"margin-left:1.0in">
<span style=3D"font-size:11.0pt;font-family:&quot;Microsoft Sans Serif&quot=
;,sans-serif;color:black">addresses for other interfaces is for them to be =
communicated</span><u></u><u></u></p>
<p class=3D"MsoNormal" style=3D"margin-left:1.0in">
<span style=3D"font-size:11.0pt;font-family:&quot;Microsoft Sans Serif&quot=
;,sans-serif;color:black">in messages by the Actor.</span><u></u><u></u></p=
>
<p class=3D"MsoNormal" style=3D"margin-left:1.0in">
<span style=3D"font-size:11.0pt;font-family:&quot;Microsoft Sans Serif&quot=
;,sans-serif;color:black">=C2=A0</span><u></u><u></u></p>
<p class=3D"MsoNormal" style=3D"margin-left:1.0in">
<span style=3D"font-size:11.0pt;font-family:&quot;Microsoft Sans Serif&quot=
;,sans-serif;color:black">In this respect, Java and C# are *<b>not</b>* pro=
per Actor programming languages</span><u></u><u></u></p>
<p class=3D"MsoNormal" style=3D"margin-left:1.0in">
<span style=3D"font-size:11.0pt;font-family:&quot;Microsoft Sans Serif&quot=
;,sans-serif;color:black">because it is possible to *<b>externally</b>* cas=
t from one interface of an Actor to another :-(</span><u></u><u></u></p>
<p class=3D"MsoNormal" style=3D"margin-left:1.0in">
<span style=3D"font-size:11.0pt;font-family:&quot;Microsoft Sans Serif&quot=
;,sans-serif;color:black">=C2=A0</span><u></u><u></u></p>
<p class=3D"MsoNormal" style=3D"margin-left:1.0in">
<span style=3D"font-size:11.0pt;font-family:&quot;Microsoft Sans Serif&quot=
;,sans-serif;color:black">Cheers,</span><u></u><u></u></p>
<p class=3D"MsoNormal" style=3D"margin-left:1.0in">
<span style=3D"font-size:11.0pt;font-family:&quot;Microsoft Sans Serif&quot=
;,sans-serif;color:black">Carl</span><u></u><u></u></p>
<p class=3D"MsoNormal" style=3D"margin-left:1.0in">
<span style=3D"font-size:11.0pt;font-family:&quot;Microsoft Sans Serif&quot=
;,sans-serif;color:black">=C2=A0</span><u></u><u></u></p>
<p class=3D"MsoNormal" style=3D"margin-left:1.0in">
<span style=3D"font-size:11.0pt;font-family:&quot;Microsoft Sans Serif&quot=
;,sans-serif;color:black">=C2=A0</span><u></u><u></u></p>
<p class=3D"MsoNormal" style=3D"margin-left:1.5in">
<b><span style=3D"font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-ser=
if">From:</span></b><span style=3D"font-size:11.0pt;font-family:&quot;Calib=
ri&quot;,sans-serif">
<a href=3D"mailto:friam-/[email protected]" target=3D"_blank">friam@googlegro=
ups.com</a> [mailto:<a href=3D"mailto:friam-/[email protected]" target=3D"_bl=
ank">friam-/[email protected]</a>]
<b>On Behalf Of </b>Tom Van Cutsem<br>
<b>Sent:</b> Monday, February 16, 2015 12:24<br>
<b>To:</b> <a href=3D"mailto:friam-/[email protected]" target=3D"_blank">fria=
[email protected]</a><br>
<b>Cc:</b> Discussion of E and other capability languages<br>
<b>Subject:</b> Re: [friam] Classification of actor languages</span><u></u>=
<u></u></p>
<div>
<div>
<p class=3D"MsoNormal" style=3D"margin-left:1.5in">
=C2=A0<u></u><u></u></p>
<div>
<p class=3D"MsoNormal" style=3D"margin-left:1.5in">
Hi Carl,<u></u><u></u></p>
<div>
<p class=3D"MsoNormal" style=3D"margin-left:1.5in">
=C2=A0<u></u><u></u></p>
<div>
<p class=3D"MsoNormal" style=3D"margin-left:1.5in">
2015-02-14 1:19 GMT+01:00 Carl Hewitt &lt;<a href=3D"mailto:hewitt@irobust.=
org" target=3D"_blank">[email protected]</a>&gt;:<u></u><u></u></p>
<blockquote style=3D"border:none;border-left:solid #cccccc 1.0pt;padding:0i=
n 0in 0in 6.0pt;margin-left:4.8pt;margin-top:5.0pt;margin-right:0in;margin-=
bottom:5.0pt">
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<span style=3D"font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;=
color:#1f497d">Of course, an Actor can implement multiple interfaces.</span=
><u></u><u></u></p>
<p class=3D"MsoNormal" style=3D"margin-left:1.5in">
<span style=3D"font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;=
color:#1f497d">=C2=A0</span><u></u><u></u></p>
<p class=3D"MsoNormal" style=3D"margin-left:1.5in">
<span style=3D"font-size:11.0pt;font-family:&quot;Calibri&quot;,sans-serif;=
color:#1f497d">I am wondering how a =E2=80=9Cfacet=E2=80=9D relates to an i=
nterface.</span><u></u><u></u></p>
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</div>
</blockquote>
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=C2=A0<u></u><u></u></p>
</div>
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<p class=3D"MsoNormal" style=3D"margin-left:1.5in">
Indeed, an actor can implement multiple interfaces, but this typically mean=
s that anyone having a reference to the actor can send any message from the=
 union of all interface methods. By contrast, in a vat with multiple facets=
, a reference to a facet provides
 access to only the methods exposed by that facet. Thus, facets make it eas=
ier to restrict authority.<u></u><u></u></p>
</div>
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<p class=3D"MsoNormal" style=3D"margin-left:1.5in">
=C2=A0<u></u><u></u></p>
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Of course, one could encode facets in a pure actor model, by passing a toke=
n designating the facet as part of the message. The actor can be programmed=
 to dispatch the message to an internal object only if the token matches. B=
ut this would be an encoding of
 the vat model in a pure actor model.<u></u><u></u></p>
</div>
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<p class=3D"MsoNormal" style=3D"margin-left:1.5in">
=C2=A0<u></u><u></u></p>
</div>
<div>
<p class=3D"MsoNormal" style=3D"margin-left:1.5in">
Cheers,<u></u><u></u></p>
</div>
<div>
<p class=3D"MsoNormal" style=3D"margin-left:1.5in">
Tom<u></u><u></u></p>
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=C2=A0<u></u><u></u></p>
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-- <u></u><u></u></p>
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=C2=A0 =C2=A0 Cheers,<br>
=C2=A0 =C2=A0 --MarkM<u></u><u></u></p>
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<u></u><u></u></p>
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<p class=3D"MsoNormal" style=3D"margin-left:.5in">=C2=A0 =C2=A0 Cheers,<br>
=C2=A0 =C2=A0 --MarkM<u></u><u></u></p>
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</div><div class=3D"HOEnZb"><div class=3D"h5">


<p></p>

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</div></div></blockquote></div><br><br clear=3D"all"><div><br></div>-- <br>=
<div class=3D"gmail_signature">=C2=A0 =C2=A0 Cheers,<br>=C2=A0 =C2=A0 --Mar=
kM</div>
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