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[XML-DEV Mailing List Archive Home] [By Thread] [By Date] [Recent Entries] [Reply To This Message] Re: ASN.1 is an XML Schema Language (Fix those lists!)and Bina
On Sat, 1 Nov 2003 23:16:03 -0500
"Alessandro Triglia" <sandro@m...> wrote:
> Rich Salz ha scritto:
> >
> > I think you misunderstand Simon. Does ASN.1/X.694 have the
> > equivalent of a "text node"? For example:
> > <foo>this is <item>1<item> line of text with
> > <item>2</item> numbers in it.</foo>
> >
> > What about
> > <foo>A second line with <item>1<item>, <item>2</item>, no,
> > <item>3</item> numbers.</foo>
> >
> > In XML Schema, those match the same definition of foo. How
> > do you write the equivalent in ASN.1/X.694?
Please note the question. The answer doesn't address it.
> ASN.1 supports mixed content in the "Extended XML encoding rules"
> (EXTENDED-XER).
>
> You can write a type definition such as the following:
>
> ----------------------
> MyElementTypeWithMixedContent ::= [EMBED-VALUES] SEQUENCE {
> embed-values SEQUENCE OF UTF8String,
> an-attribute [ATTRIBUTE] INTEGER,
> another-attribute [ATTRIBUTE] UTF8String,
> a-child-element AnotherElementType,
> another-child-element INTEGER
> }
> ----------------------
>
> [EMBED-VALUES] and [ATTRIBUTE] are examples of "XER encoding
> instructions".
>
> The [EMBED-VALUES] encoding instruction assigned to the SEQUENCE type
> causes the multiple strings of the "embed-values" component (the first
> component of the SEQUENCE) to provide the text that is interleaved
> with the child elements (before the first one, between each pair, and
> after the last one). In this example, there are two (mandatory) child
> elements ("a-child-element" and "another-child-element"), so there
> must be exactly three strings(possibly empty) in the SEQUENCE OF
> UTF8String.
But that isn't mixed content. Not in the XML sense. If I *must* write
<p>String <b>emphasized</b> the end.</p> But I *want* to write
<p>String <b>some <i>real nonsense</i>, no?</b> Or perhaps
<b>not</b>.</p>
Classic document-style mixed content. Very useful stuff if, for
instance, you're embedding documentation into a product description.
The example provided, if I understand it correctly, cannot support that.
ASN.1 as a non-mixed-content schema language for XML that has the
ability to generate [unparsable, disastrously fragile*] compact binary
structures has interesting use cases. An inability to support mixed
content means it isn't a replacement for DTDs, WXS, or RNG, all of which
do have that capability.
Amy!
* she didn't really say that, did she?
--
Amelia A. Lewis amyzing {at} talsever.com
According to Business Week, in the 1990s the ratio between a chief
executive's salary and the takehome pay of the typical, feckless,
whining grunt on the shopfloor rose from 85:1 to 475:1. (In the UK,
which is seeing a vigorous popular backlash against "fat cat" pay
packets, the ratio is 24:1).
-- The Register
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