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> -----Original Message----- > From: Roger L. Costello [mailto:costello@m...] > Sent: Wednesday, January 12, 2005 8:45 AM > To: 'XML Developers List' > Subject: A bunch of components, but no mandated > organization - reasonable? > > Hi Folks, > > Suppose that: > > 1. There exist a collection of "components", and each > component is well-defined and understood. > > 2. There does NOT exist any rules which specify how the > components should be assembled. > > If I assemble some of the components into a certain > structure, and send the structure to you, will you be able to > understand my structure? Regarding the multiple references to "you": Is "you" a person, or a machine, or both? Kind Regards, Joseph Chiusano Booz Allen Hamilton Strategy and Technology Consultants to the World > Let me be a bit more concrete. Suppose that: > > 1. There exist a collection of information components, and > each information component is well-defined and understood. > Some examples of information components might include - a > missile information component (this component provides > information about a missile, such as its direction, speed, > warhead type, etc), an aircraft information component (this > component provides information about an aircraft, such as its > altitude, wingspan, speed, etc). > > 2. There does NOT exist any rules which specify how the > information components should be assembled. In other words, > there is no grammar which dictates how the components must be > bound together. > > If I assemble some of the information components into a > certain structure, and send the structure to you, will you be > able to understand my information structure? > > Can information be transmitted in a world where the building > blocks are understood, but no grammar exists? > > Is a grammar necessary for information transfer? > > Let me give a simple example. Suppose that: > > 1. There exists these three components - A, B, C. And > everyone knows the meaning of each component. > > 2. There are no rules that specify how A, B, or C should be > organized, nor the number of occurrences of each. > > Suppose that I create this message: AACABBAC. And I send it > to you. Will you be able to understand my message? > > Consider the English language. Suppose that: > > 1. The English language was just comprised of a bunch of > words (and each word is understood), ... > > 2. ... but there was no English grammar. > > If I compose a sentence using these words, will you be able > to understand my sentence? > > Consider XML Schemas. Suppose that: > > 1. An XML Schema declares a bunch of independent elements > (i.e., components) and each component is understood. For > example, here's a Book component: > > <xsd:element name="Book"> > <xsd:complexType> > <xsd:all> > <xsd:element name="Title" type="xsd:string"/> > <xsd:element name="Author" type="xsd:string"/> > <xsd:element name="Date" type="xsd:date"/> > <xsd:element name="ISBN" type="xsd:string"/> > <xsd:element name="Publisher" type="xsd:string"/> > </xsd:all> > </xsd:complexType> > </xsd:element> > > Here's a BookCover component: > > <xsd:element name="BookCover"> > <xsd:complexType> > <xsd:choice> > <xsd:element > name="Hardcover"><xsd:complexType/></xsd:element> > <xsd:element > name="Softcover"><xsd:complexType/></xsd:element> > </xsd:choice> > </xsd:complexType> > </xsd:element> > > Everyone understands the meaning of each component in the Schema. > > 2. But there is no declaration tying the components together, > e.g., there is no overarching element declaration that > relates the Book component with the BookCover component. > > If I create an XML instance document using the components and > send the instance document to you, will you be able to > understand my data? > > /Roger > > > > > ----------------------------------------------------------------- > The xml-dev list is sponsored by XML.org > <http://www.xml.org>, an initiative of OASIS > <http://www.oasis-open.org> > > The list archives are at http://lists.xml.org/archives/xml-dev/ > > To subscribe or unsubscribe from this list use the subscription > manager: <http://www.oasis-open.org/mlmanage/index.php> > >
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