Hi Folks,
Below I have summarized
our discussion on XML and media types (MIME). Please let me know if there
are any inaccuracies in the summary. /Roger
A Summary of XML and Media Types (MIME)
What is XML’s MIME Type?
At this URL is a list of the 350 different MIME types:
http://www.iana.org/assignments/media-types/
In this list you will see two different MIME types for
XML:
application/xml
text/xml
The later MIME type (text/xml) has been deprecated. Thus, the official MIME
type for XML is:
application/xml
Note the format for expressing MIME types – it contains
two parts, separated by a slash:
type/subtype
The Editor used to Create the XML
Determines its MIME Type
Interestingly, you may have a document which contains XML
and yet its MIME type may not be application/xml.
For example, take this simple XML:
<?xml version="1.0"?>
<root>
Blah
</root>
and put it into Word (save it as a .doc file). The
MIME type is:
application/msword
Conversely, if you put the same XML into Notepad, the
MIME type is:
application/xml
Why is that? Why is it that if you put XML into one
editor (Word)
you get a MIME type that is specific to the editor, whereas if you put XML into
another editor (Notepad)
you get a MIME type that is independent of the editor?
The answer is this: when the XML
is put into Word,
the Word
application wraps the XML with a bunch of Word-specific stuff (the
wrapper stuff is not visible). Consequently, the Word
document isn't
something you can feed directly into an XML parser.
Conversely, Notepad does not wrap the
XML with anything. The document is pure XML, it can be fed directly into
an XML parser, and thus it has a MIME type of application/xml.
Suppose that you put the XML into Wordpad, what is its MIME
type?
Answer: it depends on how you save the file. If you
save it as a text document (SaveAs = Text Document) then the MIME type will be application/xml. If you
save it as Rich Text (SaveAs = Rich Text) then the editor will wrap the XML in
some stuff, and the MIME type will be different – it will be text/richtext.
Lastly, suppose that you put the XML into Notepad
and then compress it using Winzip, what is its MIME type?
Answer: application/zip
Further Information
Elliotte Rusty Harold has written an excellent article on
this subject:
http://www-128.ibm.com/developerworks/xml/library/x-mxd2.html
Acknowledgements
I would like to gratefully acknowledge the excellent
inputs from these people:
Mitch Amiano
Dave Pawson
Bryan Rasmussen
Henri Sivonen
