How to use binary data with XML?

[Jonathan Borden]

Roger L. Costello wrote:
>I have a few questions on using binary data (e.g., gif, jpeg images)
>with XML.
>
>(1)  Binary data isn't actually put in an XML file, correct? i.e., the
>binary data is _not_ inline, correct?  An XML file just contains ASCII
>text, correct?

    Binary data can be embedded inline using base64 encoding. I have placed
a demo of a MIME -> XML converter, XMTP, which demonstrates this at
test-xmtp at jabr.ne.mediaone.net. If you send an E-mail with a binary image
attachment, it will convert the multipart MIME message into XML (with inline
binary parts) and E-mail you back the response.

>
>(2)  Just like in HTML, binary data is _referenced_ by the XML document,
>correct?
>

This article discusses uses of binary data and XML.

http://www.xml.com/xml/pub/98/07/binary/binary.html

>(3) Is this the correct way of using binary data:
>
>DTD:
>
><!NOTATION jpeg PUBLIC "JPEG">
><!NOTATION gif PUBLIC "GIF">
>
><!ENTITY bostonGIF SYSTEM "http://www.maps.com/boston.gif" NDATA gif>
><!ENTITY bostonJPEG SYSTEM "http://www.maps.com/boston.jpeg" NDATA jpeg>
>
><!ELEMENT map (image)>
><!ELEMENT image EMPTY>
><!ATTLIST image
>              src  ENTITY #REQUIRED
>              desc CDATA  #IMPLIED>
>
>XML:
>
><map>
>    <image src="bostonGIF"
>           desc="Map of Boston"/>
></map>
>
>Here we see an XML document _referencing_ a file containg binary data.
>The binary data is not actually inline.  Is this how it's done?  /Roger
>

    With <image src="..."> src refers to a link to an external binary data
object. It is the job of the software which traverses the link to get you
the data. The URL http://www.maps.com/boston.gif will be identified by its
NOTATION internally as well as via its MIME Content-Type: when the link is
traversed via the HTTP protocol.

Jonathan Borden
http://jabr.ne.mediaone.net




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