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Hi.
>
> The previous also suggests that grammars and protocols are fundamentally
> different; and begs the question as to whether they can be reasonable
> compared.
>
> But let's try another conjecture: "All exchanges require a protocol." If
> there were no protocol, then it would be only luck that caused an
> exchange
> to occur. But maybe luck is ok... So let me modify the above to be: "All
> purposeful exchanges require a protocol." Another: "Exchange protocols
> may
> be implicit as well as explicit." Must protocols be binary? Can't
> protocols
> be unary? Terniary? Etc... Can protocols be passive?
Is this another way of saying that to exchange meaning we need both a
channel for communication and a meaningful context in which the
information exchange can take place. And I suppose also a way to
interpret the information once we have it, though I'm unclear if that can
be fully decoupled from context.
> Ok... so there must be a protocol, and there may be a grammar (to
> interpret
> the result of the exchange). What happens if you put building debris or
> garden debris out for the trash collector? I'm guessing it wouldn't be
> picked up. Why? Besides a protocol, he uses a "grammar" to interpret
> things
> which you are exchanging.
I heard (I have no idea if this is true) that in Switzerland they use a
special blue garbage bag. In order for your garbage to be picked up, it
needs to be in one of these bags. The bags are purchased at sepcial
outlets and the purchase price includes the cost of pickup service.
Pickup for sorted recyclables is free.
I'm going to hazard that the blue bags are part of the protocol, although
to the extent that the garbage collectors perform "validation" based on
bag color, maybe they can be seen as grammar.
>
> -----Original Message-----
> From: Roger L. Costello [mailto:costello@mitre.org]
> Sent: Friday, January 14, 2005 8:42 AM
> To: 'XML Developers List'
> Subject: RE: [xml-dev] A bunch of components, but no mandated
> organization -
> reasonable?
>
> Hi Folks,
>
> Many thanks for the outstanding messages!
>
> Yesterday Michael Kay made an insightful observation. He noted that
> there
> can be an effective exchange of information when there exists a
> "protocol"
> between the exchanging parties:
>
>> Of course it's possible to set up a system in which anyone who receives
>> a
>> customer record is expected to interpret it as meaning "please update
>> the
>> information you hold on this customer". Equally, it's possible to set
>> up a
>> system in which anyone who receives a customer record is expected to
>> interpret it as meaning "please phone this customer and find out what he
>> wants". Any bunch of bits you send me is meaningful if we've agreed a
>> protocol, and meaningless otherwise.
>
> Thus, if there exists a protocol between us then I can dynamically
> assemble
> a bunch of components and send them to you. And you will be able to
> dynamically understand my assembly!
>
> Let me give some concrete examples.
>
> Example - Trash Collection
>
> Every Wednesday morning I bring all my trash out to the front of my
> house.
> During the day a trash collector comes along and picks up the trash.
> When I
> return home in the evening the trash is gone.
>
> Information (trash) was exchanged. And it occurred without a-priori
> knowledge by either party of the specific transaction that would occur.
> The
> exchange was possible because:
>
> (1) Each party understood the components (containers of trash), and
>
> (2) There existed a protocol between the sender (me) and the receiver
> (the
> trash collector).
>
> The protocol employed: "I give, you take".
>
> Example - Browsers
>
> I have created some HTML pages and placed them on my web site. When your
> browser visits my web site it will make effective use of the stuff that I
> have put in my HTML pages.
>
> Again, information was exchanged. And it without a-priori knowledge by
> either party of the specific transaction that would occur. The exchange
> was
> possible because:
>
> (1) Each party understood the components (HTML documents), and
>
> (2) There existed a protocol between the sender (my web server) and the
> receiver (your browser).
>
> The protocol employed: "I give, you take".
>
> I suspect that the "I give, you take" protocol is a common, powerful
> protocol. Can you think of other common, powerful protocols?
>
> Summary: Transferring Information using a Shared Grammar versus a Shared
> Protocol
>
> Given a bunch of components, how can the information in those components
> be
> effectively transferred between you and I? We seem to be narrowing in on
> two approaches:
>
> 1. Shared Grammar: craft an XML Schema that completely lays out the order
> and number of occurrences of each component. That is, completely specify
> the grammar for the components. The grammar (XML Schema) is then the
> contract between sender and receiver.
>
> 2. Shared Protocol: define an exchange protocol. The form of the
> assembly
> of components that are sent is unspecified and irrelevant.
>
> [Tangential comment: there is a philosopher, Karl Popper, who wrote
> (paraphrasing), "The quickest way to move a science forward is through
> the
> use of provocative conjectures". In the spirit of Karl Popper I thus
> make
> the following provocative conjecture.]
>
> Conjecture: Information exchange using shared protocols is a superior
> approach to information exchange using shared grammars.
>
> In other words, when you create an XML Schema simply declare a bunch of
> independent components, but don't mandate any particular ordering of
> them.
>
> [Another tangential comment: Popper says that after making a conjecture
> it
> is important to test the conjecture. So, let's test the conjecture.]
>
> Test 1: Support for information exchange in a dynamically changing
> environment: the Shared Protocol approach is a "loosely coupled"
> approach.
> That is, the nature of the "payload" is irrelevant (I use the term
> "payload"
> here as it just dawned on me that HTTP is a "protocol" and the
> information
> transferred using the HTTP protocol is called a "payload").
>
> Conversely, the Shared Grammar approach is not well-suited to dynamic
> environments. Witness the great amount of effort and coordination that
> is
> required to alter an XML Schema.
>
> Test 2: ??? (What are some other tests that might be applied to the two
> approaches?)
>
> /Roger
>
>
>
>
>
>
>
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>
>
>
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--
.:||:._.:||:._.:||:._.:||:._.:||:._.:||:._.:||:._.:||:._.:||:._.:||:._.:||:.
Nathan Young
A: ncy1717
E: natyoung@cisco.com
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