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<h1><a name="title" id="title"></a>Describing Media Content of
Binary Data in XML</h1>
<h2><a name="w3c-doctype" id="w3c-doctype"></a>W3C Working Group
Note 4 May 2005</h2>
<dl>
<dt>This version:</dt>
<dd><a href=
"http://www.w3.org/TR/2005/NOTE-xml-media-types-20050504">http://www.w3.org/TR/2005/NOTE-xml-media-types-20050504</a></dd>
<dt>Latest version:</dt>
<dd><a href=
"http://www.w3.org/TR/xml-media-types">http://www.w3.org/TR/xml-media-types</a></dd>
<dt>Previous version:</dt>
<dd><a href=
"http://www.w3.org/TR/2005/NOTE-xml-media-types-20050502">http://www.w3.org/TR/2005/NOTE-xml-media-types-20050502</a></dd>
<dt>Editors:</dt>
<dd>Anish Karmarkar, Oracle</dd>
<dd>Ümit Yalçınalp, SAP</dd>
</dl>
<p class="copyright"><a href=
"http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a>&nbsp;©&nbsp;2005&nbsp;<a href="http://www.w3.org/"><acronym title="World Wide Web Consortium">W3C</acronym></a><sup>®</sup>
(<a href="http://www.csail.mit.edu/"><acronym title=
"Massachusetts Institute of Technology">MIT</acronym></a>, <a href=
"http://www.ercim.org/"><acronym title=
"European Research Consortium for Informatics and Mathematics">ERCIM</acronym></a>,
<a href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved.
W3C <a href=
"http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
<a href=
"http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>
and <a href=
"http://www.w3.org/Consortium/Legal/copyright-documents">document
use</a> rules apply.</p>
</div>
<hr />
<div>
<h2><a name="abstract" id="abstract"></a>Abstract</h2>
<p>This document addresses the need to indicate the content-type
associated with binary element content in an XML document and the
need to specify, in XML Schema, the expected content-type(s)
associated with binary element content. It is expected that the
additional information about the content-type will be used for
optimizing the handling of binary data that is part of a Web
services message.</p>
</div>
<div>
<h2><a name="status" id="status"></a>Status of this Document</h2>
<p><em>This section describes the status of this document at the
time of its publication. Other documents may supersede this
document. A list of current W3C publications and the latest
revision of this technical report can be found in the <a href=
"http://www.w3.org/TR/">W3C technical reports index</a> at
http://www.w3.org/TR/.</em></p>
<p>This document is a <a href=
"http://www.w3.org/2004/02/Process-20040205/tr.html#q74">W3C
Working Group Note</a>. This document includes the resolution of
the comments received on the <a href=
"http://www.w3.org/TR/2004/WD-xml-media-types-20041102/">Last Call
Working Draft</a> previously published. The comments on this
document and their resolution can be found in the <a href=
"http://dev.w3.org/cvsweb/%7Echeckout%7E/2002/ws/desc/issues/wsd-issues.html">
Web Services Description Working Group's issues list</a>.</p>
<p>There is no technical difference between this document and the 2
May 2005 version; the acknowledgement section has been updated to
thank external contributors. A <a href="diff.html">diff-marked
version against the previous version of this document</a> is
available.</p>
<p>It has been produced jointly by the <a href=
"http://www.w3.org/2000/xp/Group/">XML Protocol Working Group</a>,
and the <a href="http://www.w3.org/2002/ws/desc/">Web Services
Description Working Group</a>, which are part of the <a href=
"http://www.w3.org/2002/ws/Activity">Web Services Activity</a>.</p>
<p>No further work on this topic is planned at this point. Errors
in this document can be reported to the public <a href=
"mailto:public-ws-media-types@w3.org">public-ws-media-types@w3.org</a>
mailing list (<a href=
"http://lists.w3.org/Archives/Public/public-ws-media-types/">public
archive</a>).</p>
<p>Publication as a Working Group Note does not imply endorsement
by the W3C Membership. This is a draft document and may be updated,
replaced or obsoleted by other documents at any time. It is
inappropriate to cite this document as other than work in
progress.</p>
</div>
<div class="toc">
<h2><a name="contents" id="contents"></a>Table of Contents</h2>
<p class="toc">1 <a href="#introduction">Introduction</a><br />
&nbsp;&nbsp;&nbsp;&nbsp;1.1 <a href="#notational">Notational
Conventions</a><br />
&nbsp;&nbsp;&nbsp;&nbsp;1.2 <a href=
"#requirements">Requirements</a><br />
2 <a href="#declaration">Attributes for Declaring
Content-Type</a><br />
&nbsp;&nbsp;&nbsp;&nbsp;2.1 <a href=
"#contentType">xmime:contentType Attribute</a><br />
&nbsp;&nbsp;&nbsp;&nbsp;2.2 <a href=
"#expectedContentTypes">xmime:expectedContentTypes
Attribute</a><br />
3 <a href="#usage">Declaring Content-Type for Binary Data</a><br />
&nbsp;&nbsp;&nbsp;&nbsp;3.1 <a href="#role">Role of
xmime:expectedContentTypes Schema Annotation Attribute</a><br />
4 <a href="#more-ex">Examples</a><br />
&nbsp;&nbsp;&nbsp;&nbsp;4.1 <a href="#static">Binary Data with
Known Media Type</a><br />
&nbsp;&nbsp;&nbsp;&nbsp;4.2 <a href="#example-with-q-param">Binary
Data with Preferred Media Type</a><br />
5 <a href="#normative-references">Normative References</a><br />
6 <a href="#informative-references">Informative
References</a><br /></p>
<h3><a name="appendices" id="appendices"></a>Appendices</h3>
<p class="toc">A <a href="#ack">Acknowledgements</a><br />
B <a href="#schema">Schema</a><br /></p>
</div>
<hr />
<div class="body">
<div class="div1">
<h2><a name="introduction" id="introduction"></a>1
Introduction</h2>
<p>Data sent and received over the Web typically uses the MIME
media type defined by <a href="#rfc2046">[IETF RFC 2046]</a>, as
the type system. For example, "image/jpeg", "application/pdf".
There is a need to indicate the content-type of the XML element
content, for example, in messages sent and received by Web
services. There is also a need to express the content-type
information using <a href="#XMLSchemaP2">[XML Schema:
Datatypes]</a> and <a href="#XMLSchemaP2">[XML Schema:
Datatypes]</a>, which is the type system used by <a href=
"#wsdl20part1">[WSDL 2.0 Part 1]</a>. This would allow XML-based
applications, such as Web services, to utilize the widely deployed
and supported MIME media type infrastructure.</p>
<p><a href="#XOP">[XOP]</a> and <a href="#MTOM">[MTOM]</a> enables
one to serialize binary content (element content that is in a
canonical lexical representation of the <em>xs:base64Binary</em>
type) in an optimized way using MIME packaging. There is a desire
to specify the content-type information of such binary element
content in a standard way in the <a href="#XMLInfoSet">[XML
Information Set]</a> and not just in the optimized serialization of
that Infoset.</p>
<p>This document specifies:</p>
<ul>
<li>
<p>An attribute (<em>xmime:contentType</em>) to indicate the
content-type of an XML element content whose type is
<em>xs:base64Binary</em> or <em>xs:hexBinary</em>. The value of the
attribute is a valid content-type string (e.g., "text/xml;
charset=utf-16"). This attribute specifies the content-type of the
element content on which it occurs.</p>
</li>
<li>
<p>A XML Schema annotation attribute
(<em>xmime:expectedContentTypes</em>) to indicate, in XML Schema,
the expected content-type(s) for an element content whose type is
<em>xs:base64Binary</em> or <em>xs:hexBinary</em>.</p>
</li>
</ul>
<p>The XML Schema annotation, <em>xmime:expectedContentTypes</em>,
specifies the expected range of values for the
<em>xmime:contentType</em> attribute and the expected range of
content-type for the binary element content.</p>
<p>Note that the use of this mechanism, in particular the
<em>xmime:contentType</em> attribute, does not require the
implementation, in whole or in part, of XML Schema. In the absence
of XML Schema the type information (xs:base64Binary or
xs:hexBinary) may have to be provided via other mechanisms; for
example, using <em>xsi:type</em>.</p>
<div class="div2">
<h3><a name="notational" id="notational"></a>1.1 Notational
Conventions</h3>
<p>The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL"
in this document are to be interpreted as described in <a href=
"#rfc2119">[IETF RFC 2119]</a>.</p>
<p>This specification uses properties from the XML Information Set
(see <a href="#XMLInfoSet">[XML Information Set]</a>). Such
properties are denoted by square brackets, e.g. [namespace
name].</p>
<p>This specification uses namespace prefixes that are listed in
Table 1. Note that the choice of any namespace prefix is arbitrary
and not semantically significant (see <a href="#XMLInfoSet">[XML
Information Set]</a>).</p>
<a name="tabnsprefixes" id="tabnsprefixes"></a>
<table border="1" summary=
"Mapping of prefixes used in this document to their associated namespace name">
<caption>Table 1. Prefixes and Namespaces used in this
specification</caption>
<tbody>
<tr>
<th>Prefix</th>
<th>Namespace</th>
<th>Definition</th>
</tr>
<tr>
<td>xmime</td>
<td>http://www.w3.org/2005/05/xmlmime</td>
<td>Defined by this specification</td>
</tr>
<tr>
<td>xs</td>
<td>"http://www.w3.org/2001/XMLSchema"</td>
<td>Defined in the W3C XML Schema specifications <a href=
"#XMLSchemaP1">[XML Schema: Structures]</a>, <a href=
"#XMLSchemaP2">[XML Schema: Datatypes]</a>.</td>
</tr>
<tr>
<td>xsi</td>
<td>"http://www.w3.org/2001/XMLSchema-instance"</td>
<td>Defined in the W3C XML Schema specification <a href=
"#XMLSchemaP1">[XML Schema: Structures]</a>.</td>
</tr>
</tbody>
</table>
<p>Namespace names of the general form "http://example.org/..." and
"http://example.com/..." represent application or context-dependent
URIs (see <a href="#rfc3986">[IETF RFC 3986]</a>).</p>
<p>All parts of this specification are normative, with the
exception of examples and sections explicitly marked as
"Non-Normative".</p>
</div>
<div class="div2">
<h3><a name="requirements" id="requirements"></a>1.2
Requirements</h3>
<p>This section describes the set of requirements that this
document addresses.</p>
<ol class="enumar">
<li>
<p>Define how to indicate the content-type of an XML element
content whose type is <em>xs:base64Binary</em> or
<em>xs:hexBinary</em>. This is meta-data that may be, but not
required to, used by tools to infer the specific content-type of
binary data.</p>
</li>
<li>
<p>Define how to indicate the expected content-type(s) of XML
element content whose type is <em>xs:base64Binary</em> or
<em>xs:hexBinary</em> in XML Schema. This information is needed to
define the set of content-type that a binary data may have. For
example, a Web services application may be willing to indicate that
the binary data represents an image, but leaves it to a document
instance to further specify whether it is "jpeg", or "gif". This
meta-data is not required to be present.</p>
</li>
<li>
<p>Define the acceptable format of content-type values.</p>
</li>
<li>
<p>Define the relationship between the expected and the actual
value of the content-type declared for binary data in XML
documents.</p>
</li>
</ol>
</div>
</div>
<div class="div1">
<h2><a name="declaration" id="declaration"></a>2 Attributes for
Declaring Content-Type</h2>
<p>This section defines two global <em>attribute information
item</em>s for declaring the content-type of binary data and
expected content-type(s) of binary data in XML Schema to address
requirements (1) and (2) above. Their usage is addressed in Section
<a href="#usage"><b>3 Declaring Content-Type for Binary
Data</b></a>.</p>
<div class="div2">
<h3><a name="contentType" id="contentType"></a>2.1
xmime:contentType Attribute</h3>
<p>The <code>xmime:contentType</code> <em>attribute information
item</em> has the following Infoset properties:</p>
<ul>
<li>
<p>A [local name] of <code>contentType</code>.</p>
</li>
<li>
<p>A [namespace name] of "http://www.w3.org/2005/05/xmlmime".</p>
</li>
</ul>
<p>The type of the <code>xmime:contentType</code> <em>attribute
information item</em> is <em>xs:string</em> with a minimum length
of three and all leading and trailing white space characters are
ignored.</p>
<p>The [normalized value] of the <code>xmime:contentType</code>
<em>attribute information item</em> MUST be a valid Content-Type
string, e.g., "image/png", "text/xml; charset=utf-16" as defined by
<a href="#rfc2045">[IETF RFC 2045]</a> and indicates the
content-type of the [owner element]. Note that [normalized value]
consists of normalized attribute value as defined by <a href=
"#XMLInfoSet">[XML Information Set]</a> and does not mean that two
equivalent values of <code>xmime:contentType</code> will
necessarily be equal.</p>
<p>The <code>xmime:contentType</code> <em>attribute information
item</em> allows Web services applications to optimize the handling
of the binary data defined by a <em>binary element information
item</em> and should be considered as meta-data. The presence of
the <code>xmime:contentType</code> attribute does not changes the
value of the element content.</p>
</div>
<div class="div2">
<h3><a name="expectedContentTypes" id=
"expectedContentTypes"></a>2.2 xmime:expectedContentTypes
Attribute</h3>
<p>The <code>xmime:expectedContentTypes</code> <em>attribute
information item</em> has the following Infoset properties:</p>
<ul>
<li>
<p>A [local name] of <code>expectedContentTypes</code>.</p>
</li>
<li>
<p>A [namespace name] of
<code>http://www.w3.org/2005/05/xmlmime</code>.</p>
</li>
</ul>
<p>The type of the <code>xmime:expectedContentTypes</code>
<em>attribute information item</em> is <em>xs:string</em>.</p>
<p>The value and the meaning of the
<code>xmime:expectedContentTypes</code> attribute is similar to the
value allowed for the <code>'Accept'</code> HTTP header defined by
HTTP 1.1 specification, Section 14.1 (see <a href="#rfc2616">[IETF
RFC 2616]</a>) and MUST follow the production rules defined in that
section except for the following:</p>
<ol class="enumar">
<li>
<p>The prefix <em>"Accept:"</em> MUST NOT be used.</p>
</li>
<li>
<p>The rule <em>qdtext</em> is changed from: <code>qdtext = &lt;any
TEXT except&lt;"&gt;&gt;</code> to: <code>qdtext = &lt;any CHAR
except&lt;"&gt;&gt;</code> This change is made to disallow
non-US-ASCII OCTETs.</p>
</li>
</ol>
<p>The <code>xmime:expectedContentTypes</code> <em>attribute
information item</em> is intended to be used as part of XML Schema
annotation for a <em>binary element information item</em>
declaration (see <a href="#usage"><b>3 Declaring Content-Type for
Binary Data</b></a>). This <em>attribute information item</em> is
meant to allow XML Schema authors to indicate the range of media
types and/or associated parameters that are acceptable for the
binary data. It serves as a static constrain on the
<code>xmime:contentType</code>. Users of this <em>attribute
information item</em> are urged to avoid using wild cards (for
example, "image/*") as it may lead to interoperability problems. If
the set of expected media types is not known, the use of
<code>xmime:expectedContentTypes</code> is NOT RECOMMENDED.</p>
</div>
</div>
<div class="div1">
<h2><a name="usage" id="usage"></a>3 Declaring Content-Type for
Binary Data</h2>
<p>Documents that want to specify additional content-type
information for binary data SHOULD denote this by using a
<em>binary element information item</em>. A <em>binary element
information item</em> is an <em>element information item</em>
defined with the following additional constraints.</p>
<ul>
<li>
<p>An OPTIONAL <code>xmime:contentType</code> <em>attribute
information item</em> as described above in <a href=
"#contentType"><b>2.1 xmime:contentType Attribute</b></a> .</p>
</li>
<li>
<p>The <em>character information items</em> comprising the
[children] of the <em>element information item</em> MUST conform to
the lexical constraints of <em>xs:base64Binary</em> or
<em>xs:hexBinary</em>.</p>
</li>
</ul>
<p>If the media type identified by the value of an
<code>xmime:contentType</code> attribute information item is a text
based media type then the value of the
<code>xmime:contentType</code> attribute information item SHOULD
include a <code>charset</code> parameter.</p>
<p>For authoring convenience, two types
<code>xmime:base64Binary</code> and <code>xmime:hexBinary</code>
are defined in <a href="#schema"><b>B Schema</b></a></p>
<div class="exampleOuter">
<div class="exampleHeader"><a name="eg-ct-required" id=
"eg-ct-required"></a>Example 1: Element with binary content and
xmime:contentType attribute</div>
<div class="exampleInner">
<pre>
&lt;?xml version="1.0" ?&gt;
&lt;xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
           xmlns:tns="http://example.com/ct-required"
           xmlns:xmime="http://www.w3.org/2005/05/xmlmime"
           targetNamespace="http://example.com/ct-required"&gt;

    &lt;xs:import namespace="http://www.w3.org/2005/05/xmlmime"
                schemaLocation="http://www.w3.org/2005/05/xmlmime"/&gt;

    &lt;!-- This element has binary content and requires the xmime:contentType
         attribute that indicates the content-type of the binary element --&gt;
    &lt;xs:element name="MyBinaryData"&gt;
      &lt;xs:complexType&gt;
        &lt;xs:simpleContent&gt;
          &lt;xs:extension base="xs:base64Binary" &gt;
            &lt;xs:attribute ref="xmime:contentType" use="required"/&gt;
          &lt;/xs:extension&gt;
        &lt;/xs:simpleContent&gt;
      &lt;/xs:complexType&gt;
    &lt;/xs:element&gt;

&lt;/xs:schema&gt;

</pre></div>
</div>
<div class="div2">
<h3><a name="role" id="role"></a>3.1 Role of
xmime:expectedContentTypes Schema Annotation Attribute</h3>
<p>The <code>xmime:expectedContentTypes</code> attribute is used
for annotating XML Schema to indicate the expected range of
content-type of the binary element content and the expected range
of values for <code>xmime:contentType</code> attribute.</p>
<p>The value of the <code>xmime:contentType</code> attribute, if
present, SHOULD be within the range specified by the
<code>xmime:expectedContentTypes</code> annotation attribute, if
specified in the schema. See Section 14.1 of <a href=
"#rfc2616">[IETF RFC 2616]</a> on how to interpret content-type
ranges that may be defined with respect to actual content. When the
<code>xmime:expectedContentTypes</code> annotation attribute
contains a wild card ("*") or a list of acceptable content-type
separated by commas (","), the schema SHOULD require the
<code>xmime:contentType</code> attribute to be present.</p>
<p>Applications that need to specify expected content-type SHOULD
use the schema annotation to declare the range of expected values.
<code>xmime:expectedContentTypes</code> annotation attribute MAY be
used in conjunction with the declaration of <em>binary element
information item</em>s or with complex type definitions that are
derived from <em>xs:base64Binary</em> or <em>xs:hexBinary</em> in
XML Schema. If the <code>xmime:expectedContentTypes</code>
annotation attribute is used in both the <em>binary element
information item</em> declaration as well as definition of the
complex type which the <em>binary element information item</em>
belongs to, then the expected range of values defined for the
<em>binary element information item</em> MUST be a subset of the
expected range of values defined for the complex type.</p>
<p>The <code>xmime:expectedContentTypes</code> annotation can be
used in conjunction with either type or element declarations.
Certain data-binding frameworks which use static type mappings can
be more specific if the <code>xmime:expectedContentTypes</code>
annotation is applied to the complexType declarations instead of
the element declarations using those types. For this reason, the
use of expectedContentTypes on element declarations using named
complex types is not recommended. An example is provided in Example
6.</p>
<p>The example below consists of a type definition,
<code>PictureType</code>, and an element declaration,
<code>Picture</code>. The <code>xmime:contentType</code> attribute
is required to be present and specifies the content-type of the
binary content. The schema annotation attribute
<code>xmime:expectedContentTypes</code> specifies that the media
type of the binary content is 'image', and the subtype name is
either 'jpeg' or 'png'.</p>
<div class="exampleOuter">
<div class="exampleHeader"><a name="eg-wildcard" id=
"eg-wildcard"></a>Example 2: Schema declaring an element with
binary content and expected media type of "image/jpeg" or
"image/png"</div>
<div class="exampleInner">
<pre>
&lt;?xml version="1.0" ?&gt;
&lt;xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
           xmlns:tns="http://example.com/wildcard"
           xmlns:xmime="http://www.w3.org/2005/05/xmlmime"
           targetNamespace="http://example.com/wildcard"&gt;

    &lt;xs:import namespace="http://www.w3.org/2005/05/xmlmime"
                schemaLocation="http://www.w3.org/2005/05/xmlmime"/&gt;


    &lt;xs:complexType name="PictureType"&gt;
       &lt;xs:simpleContent&gt;
           &lt;xs:restriction base="xmime:base64Binary" &gt;
               &lt;xs:attribute ref="xmime:contentType" use="required" /&gt;
           &lt;/xs:restriction&gt;
       &lt;/xs:simpleContent&gt;
    &lt;/xs:complexType&gt;

    &lt;!-- This element designates the range of values
         that the element definition will accept    --&gt;
    &lt;xs:element name="Picture" type="tns:PictureType"
                xmime:expectedContentTypes="image/jpeg, image/png"/&gt;

&lt;/xs:schema&gt;

</pre></div>
</div>
<p>The example document instance below conforms to the element
declaration of <code>Picture</code> and specifies that the binary
content is of type "image/png".</p>
<div class="exampleOuter">
<div class="exampleHeader"><a name="eg-wildcard-instance" id=
"eg-wildcard-instance"></a>Example 3: Document instance containing
element with binary content-type "image/png"</div>
<div class="exampleInner">
<pre>
&lt;?xml version="1.0" ?&gt;
&lt;Picture xmlns="http://example.com/wildcard"
           xmlns:xmime="http://www.w3.org/2005/05/xmlmime"
           xmime:contentType="image/png"&gt;/aWKKapGGyQ=&lt;/Picture&gt;

</pre></div>
</div>
</div>
</div>
<div class="div1">
<h2><a name="more-ex" id="more-ex"></a>4 Examples</h2>
<div class="div2">
<h3><a name="static" id="static"></a>4.1 Binary Data with Known
Media Type</h3>
<p>The examples in this section consists of a binary elements whose
media type is known in advance to be "image/jpeg".</p>
<p>In <a href="#eg-static">Example</a> 4, a fixed media type is
specified by declaring it with an annotation in conjunction with
the complex type definition. The attribute
<code>xmime:contentType</code> is not used as the media type of the
binary data is know in advance.</p>
<div class="exampleOuter">
<div class="exampleHeader"><a name="eg-static" id=
"eg-static"></a>Example 4: Element with binary content, known media
type and no xmime:contentType attribute</div>
<div class="exampleInner">
<pre>
&lt;?xml version="1.0" ?&gt;
&lt;xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
           xmlns:tns="http://example.com/know-type"
           xmlns:xmime="http://www.w3.org/2005/05/xmlmime"
           targetNamespace="http://example.com/know-type"&gt;

    &lt;xs:import namespace="http://www.w3.org/2005/05/xmlmime"
            schemaLocation="http://www.w3.org/2005/05/xmlmime"/&gt;

    &lt;xs:simpleType name="JPEGPictureType"
            xmime:expectedContentTypes="image/jpeg"&gt;
        &lt;xs:restriction base="xs:base64Binary"/&gt;
    &lt;/xs:simpleType&gt;

    &lt;xs:element name="JPEGPicture" type="tns:JPEGPictureType"/&gt;

&lt;/xs:schema&gt;

</pre></div>
</div>
<p>In <a href="#eg-static-with-ct">Example</a> 5, a fixed media
type is specified by declaring it with an annotation in conjunction
with the element declaration. The attribute
<code>xmime:contentType</code> is optionally used in document
instances to indicate the media type of the binary data.</p>
<div class="exampleOuter">
<div class="exampleHeader"><a name="eg-static-with-ct" id=
"eg-static-with-ct"></a>Example 5: Element with binary content,
known media type and optional xmime:contentType attribute</div>
<div class="exampleInner">
<pre>
&lt;?xml version="1.0" ?&gt;
&lt;xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
           xmlns:tns="http://example.com/know-type"
           xmlns:xmime="http://www.w3.org/2005/05/xmlmime"
           targetNamespace="http://example.com/know-type"&gt;

    &lt;xs:import namespace="http://www.w3.org/2005/05/xmlmime"
            schemaLocation="http://www.w3.org/2005/05/xmlmime"/&gt;

    &lt;xs:element name="JPEGPicture" type="xmime:base64Binary"
            xmime:expectedContentTypes="image/jpeg" /&gt;

&lt;/xs:schema&gt;

</pre></div>
</div>
</div>
<div class="div2">
<h3><a name="example-with-q-param" id=
"example-with-q-param"></a>4.2 Binary Data with Preferred Media
Type</h3>
<p>This example illustrates that binary data with media type
'image/jpeg' is preferred but binary data with media type of
'image/tiff' is also allowed (with a lower preference).</p>
<div class="exampleOuter">
<div class="exampleHeader"><a name="eg-preferred" id=
"eg-preferred"></a>Example 6: Element with binary content and
preferred media type</div>
<div class="exampleInner">
<pre>
&lt;?xml version="1.0" ?&gt;
&lt;xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
           xmlns:tns="http://example.com/preferred-type"
           xmlns:xmime="http://www.w3.org/2005/05/xmlmime"
           targetNamespace="http://example.com/preferred-type"&gt;

    &lt;xs:import namespace="http://www.w3.org/2005/05/xmlmime"
            schemaLocation="http://www.w3.org/2005/05/xmlmime"/&gt;


    &lt;xs:complexType name="JPEGPreferredPictureType"
            xmime:expectedContentTypes="image/jpeg;q=1.0, image/tiff;q=0.8"&gt;
        &lt;xs:simpleContent&gt;
            &lt;xs:restriction base="xmime:base64Binary" &gt;
                &lt;xs:attribute ref="xmime:contentType" use="required" /&gt;
            &lt;/xs:restriction&gt;
        &lt;/xs:simpleContent&gt;
    &lt;/xs:complexType&gt;

    &lt;xs:element name="JPEGPeferredPicture"
            type="tns:JPEGPreferredPictureType"/&gt;

&lt;/xs:schema&gt;

</pre></div>
</div>
</div>
</div>
<div class="div1">
<h2><a name="normative-references" id="normative-references"></a>5
Normative References</h2>
<dl>
<dt class="label"><a name="XMLSchemaP1" id="XMLSchemaP1"></a>XML
Schema: Structures</dt>
<dd><a href=
"http://www.w3.org/TR/2004/REC-xmlschema-1-20041028/"><cite>XML
Schema Part 1: Structures Second Edition</cite></a>, H. Thompson,
D. Beech, M. Maloney, and N. Mendelsohn, Editors. World Wide Web
Consortium Recommendation, 28 October 2004. (See
http://www.w3.org/TR/2004/REC-xmlschema-1-20041028/.)</dd>
<dt class="label"><a name="XMLSchemaP2" id="XMLSchemaP2"></a>XML
Schema: Datatypes</dt>
<dd><a href=
"http://www.w3.org/TR/2004/REC-xmlschema-2-20041028/"><cite>XML
Schema Part 2: Datatypes Second Edition</cite></a>, P. Byron and A.
Malhotra, Editors. World Wide Web Consortium Recommendation, 28
October 2004. (See
http://www.w3.org/TR/2004/REC-xmlschema-2-20041028/.)</dd>
<dt class="label"><a name="rfc3986" id="rfc3986"></a>IETF RFC
3986</dt>
<dd><a href="http://www.ietf.org/rfc/rfc3986.txt"><cite>Uniform
Resource Identifiers (URI): Generic Syntax</cite></a>, T.
Berners-Lee, R. Fielding, L. Masinter, January 2005. (See
http://www.ietf.org/rfc/rfc3986.txt.)</dd>
<dt class="label"><a name="rfc2045" id="rfc2045"></a>IETF RFC
2045</dt>
<dd><a href="http://www.ietf.org/rfc/rfc2045.txt"><cite>RFC 2045 -
Multipurpose Internet Mail Extensions (MIME) Part One: Format of
Internet Message Bodies</cite></a>, N. Freed, N. Borenstein,
November 1996. (See http://www.ietf.org/rfc/rfc2045.txt.)</dd>
<dt class="label"><a name="rfc2046" id="rfc2046"></a>IETF RFC
2046</dt>
<dd><a href="http://www.ietf.org/rfc/rfc2046.txt"><cite>RFC 2046 -
Multipurpose Internet Mail Extensions (MIME) Part Two: Media
Types</cite></a>, N. Freed, N. Borenstein, November 1996. (See
http://www.ietf.org/rfc/rfc2046.txt.)</dd>
<dt class="label"><a name="rfc2616" id="rfc2616"></a>IETF RFC
2616</dt>
<dd><a href=
"http://www.w3.org/Protocols/rfc2616/rfc2616.html"><cite>Hypertext
Transfer Protocol--HTTP 1.1</cite></a>, R. Fielding, J. Gettys, J.
Mogul, H. Frystyk, L. Masinter, P. Leach, T. Berners-Lee, June
1999. (See http://www.w3.org/Protocols/rfc2616/rfc2616.html.)</dd>
<dt class="label"><a name="rfc2119" id="rfc2119"></a>IETF RFC
2119</dt>
<dd><a href="http://www.ietf.org/rfc/rfc2119.txt"><cite>Key words
for use in RFCs to Indicate Requirement Levels</cite></a>, S.
Bradner, Author. Internet Engineering Task Force, June 1999. (See
http://www.ietf.org/rfc/rfc2119.txt.)</dd>
<dt class="label"><a name="XMLInfoSet" id="XMLInfoSet"></a>XML
Information Set</dt>
<dd><a href=
"http://www.w3.org/TR/2001/REC-xml-infoset-20011024/"><cite>XML
Information Set (Second Edition)</cite></a>, J. Cowan and R. Tobin,
World Wide Web Consortium Recommendation, 4 February 2004. (See
http://www.w3.org/TR/2001/REC-xml-infoset-20011024/.)</dd>
</dl>
</div>
<div class="div1">
<h2><a name="informative-references" id=
"informative-references"></a>6 Informative References</h2>
<dl>
<dt class="label"><a name="wsdl20part1" id="wsdl20part1"></a>WSDL
2.0 Part 1</dt>
<dd><a href=
"http://www.w3.org/TR/2004/WD-wsdl20-20040803/"><cite>Web Services
Description Language (WSDL) Version 2.0 Part 1: Core
Language</cite></a>, Roberto Chinnici, Martin Gudgin, Jean-Jacques
Moreau, Jeffrey Schlimmer, Sanjiva Weerawarana, World Wide Web
Consortium Working Draft 3 August 2004 (See
http://www.w3.org/TR/2004/WD-wsdl20-20040803/.)</dd>
<dt class="label"><a name="XOP" id="XOP"></a>XOP</dt>
<dd><a href=
"http://www.w3.org/TR/2005/REC-xop10-20050125/"><cite>XML-binary
Optimized Packaging</cite></a>, Martin Gudgin, Noah Mendelsohn,
Mark Nottingham, Herve Ruellan, W3C Recommendation, 25 January 2005
(See http://www.w3.org/TR/2005/REC-xop10-20050125/.)</dd>
<dt class="label"><a name="MTOM" id="MTOM"></a>MTOM</dt>
<dd><a href=
"http://www.w3.org/TR/2005/REC-soap12-mtom-20050125/"><cite>SOAP
Message Transmission Optimization Mechanism</cite></a>, Martin
Gudgin, Noah Mendelsohn, Mark Nottingham, Herve Ruellan, W3C
Recommendation, 25 January 2005 (See
http://www.w3.org/TR/2005/REC-soap12-mtom-20050125/.)</dd>
</dl>
</div>
</div>
<div class="back">
<div class="div1">
<h2><a name="ack" id="ack"></a>A Acknowledgements</h2>
<p>This document is developed by the participants of the joint
media types task force formed by <a href=
"http://www.w3.org/2002/ws/desc/">Web Services Description</a> and
<a href="http://www.w3.org/2000/xp/Group/">XML Protocol</a> Working
Groups. Participants of the taskforce, specifically Martin Gudgin,
and Mark Nottingham are gratefully acknowledged.</p>
<p>The authors would also like to thank the commentors, in
particular Joe Fialli, Larry Massinter, and Henry Thompson.</p>
</div>
<div class="div1">
<h2><a name="schema" id="schema"></a>B Schema</h2>
<div class="exampleInner">
<pre>
&lt;?xml version="1.0" ?&gt;
&lt;xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
           xmlns:xmime="http://www.w3.org/2005/05/xmlmime"
           targetNamespace="http://www.w3.org/2005/05/xmlmime" &gt;

  &lt;xs:attribute name="contentType"&gt;
    &lt;xs:simpleType&gt;
      &lt;xs:restriction base="xs:string" &gt;
      &lt;xs:minLength value="3" /&gt;
      &lt;/xs:restriction&gt;
    &lt;/xs:simpleType&gt;
  &lt;/xs:attribute&gt;

  &lt;xs:attribute name="expectedContentTypes" type="xs:string" /&gt;

  &lt;xs:complexType name="base64Binary" &gt;
    &lt;xs:simpleContent&gt;
        &lt;xs:extension base="xs:base64Binary" &gt;
            &lt;xs:attribute ref="xmime:contentType" /&gt;
        &lt;/xs:extension&gt;
    &lt;/xs:simpleContent&gt;
  &lt;/xs:complexType&gt;

  &lt;xs:complexType name="hexBinary" &gt;
    &lt;xs:simpleContent&gt;
        &lt;xs:extension base="xs:hexBinary" &gt;
            &lt;xs:attribute ref="xmime:contentType" /&gt;
        &lt;/xs:extension&gt;
    &lt;/xs:simpleContent&gt;
  &lt;/xs:complexType&gt;

&lt;/xs:schema&gt;
</pre></div>
</div>
</div>
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