View source for Xml (XmlDoc function)

{{Template:XmlDoc:Xml subtitle}}
[[Category:XmlDoc methods|Xml function]]
[[Category:XmlDoc API methods]]
<!--DPL?? Category:XmlDoc methods|Xml function: Serialize XmlDoc as UTF-8 string-->
<!--DPL?? Category:XmlDoc API methods|Xml (XmlDoc function): Serialize XmlDoc as UTF-8 string-->
<!--DPL?? Category:System methods|Xml (XmlDoc function): Serialize XmlDoc as UTF-8 string-->

This function converts an XmlDoc to its textually represented XML document
(this process is called '''serialization''',
because the text representation of a document is called the '''serial'''
form).
==Syntax==
{{Template:XmlDoc:Xml syntax}}
===Syntax terms===
<table class="syntaxTable">
<tr><th>utf8Str</th>
<td>The string serialization of the XmlDoc, encoded in UTF-8. </td></tr>
<tr><th>doc</th>
<td>XmlDoc expression, whose content is serialized. </td></tr>
<tr><th>options</th>
<td>Any combination of the following options (but single occurrences only): <br> <ul> <li><b>AllowXmlDecl</b> or <b>NoXmlDecl</b>
<p class="code">AllowXmlDecl, the default, produces the XML declaration (that is, <?xml&thinsp.version=...?>) if the declaration was set (see [[Version (XmlDoc property)|Version]]). NoXmlDecl omits the XML declaration. <li><b>Indent</b> <i><b>n</b></i>
Inserts space characters (and line-ends, as described for the next option) into the serialized string such that if the string is broken at the line-ends and displayed as a tree, the display of each lower level in the subtree is indented ''n'' spaces from the previous level's starting point.
If serialized output with an Indent value of 2 is displayed as a tree, the spacing is as in the following: <pre>     <top>       <leaf1 xx="yy">value</leaf1>       <sub>         <leaf2>value</leaf2>       </sub>     </top> </pre> <i>n</i> is a non-negative integer, and it maximum value (as of ''Sirius Mods'' version 7.0) is 254.
One of the line-end options, below, must also be specified. <li>One of the '''line-end options''' below, to provide line breaks in the output after any of the following is serialized: <ul> <li>An element start-tag, if it has any non-text node children <li>An empty element tag, or an empty element end-tag <li>A processing instruction (PI) <li>A comment <li>A text node, if it has any siblings </ul>
</p>
<table class="syntaxNested">
<tr><th>CR</th>
<td>Insert a carriage-return character as the line-end sequence in the above cases. </td></tr>
<tr><th>LF</th>
<td>Insert a linefeed character as the line-end sequence in the above cases. </td></tr>
<tr><th>CRLF</th>
<td>Insert a carriage-return character followed by a linefeed character as the line-end sequence in the above cases. </td></tr>
</table>
<p class="code"><br> <li><b>NoEmptyElt</b>
This indicates that an empty element is serialized with its start tag followed by an end tag. For example: <pre>     <middleName></middleName> </pre> If this option is not specified, the default is to serialize an empty element with an empty element tag: <pre>     <middleName/> </pre> <li><b>OmitNullElement</b>
An Element node that has no children and no Attributes will not be serialized, unless it is the top level Element in the subtree being serialized. The serialization of a child-less and Attribute-less Element is omitted, even if the Element's serialization would contain Namespace declarations in its start tag.
If an Element node has no Attributes, but has (only) Element children (one or more), and all of its children are Attribute-less and child-less, then that parent Element is serialized, even though its content in the serialization is empty. That parent is serialized with a start tag and an end tag (and an inserted line separator, if called for by the serializing method's parameter options).
For example, if the Print method display of a particular XmlDoc object is the following when OmitNullElement is ''not'' specified: <pre>     <top>        <middle>           <empty/>           <p:empty2 xmlns:p="uri:stuff"/>        </middle>     </top> </pre>
Here is the display of the XmlDoc with the OmitNullElement option specified: <pre>     <top>        <middle>        </middle>     </top> </pre>
The OmitNullElement option is available as of ''Sirius Mods'' version 7.3. <li><b>SortCanonical</b>
This indicates that namespace declarations (based on the prefix being declared) and attributes (based on the namespace URI followed by the local name) are serialized in sorted order. This can be useful, for instance, when using the Xml method to serialize a portion of an XML document for a signature.
The sort order for namespace declarations and attributes is from lowest to highest, and it uses the Unicode code ordering (for example, numbers are lower than letters).
This option was added in ''Sirius Mods'' version 6.9 as a step towards support for canonicalization. As of version 7.0, comprehensive support for canonicalized serialization is provided by the Serial method ExclCanonical option ([[??]] refid=exclcan.). </ul></td></tr>
</p>
</table>
==Usage notes==

<ul>
<li>Options may be specified in any case, for example, you can use
either <tt>NoXmlDecl</tt> or <tt>noxmldecl</tt>, interchangeably.
<li>The <i>XmlDoc</i> method object must be well-formed (that is,
it must contain an Element node).
For more information about well-formed documents, see [[??]] refid=welform..
<li>Since the result of the Xml function has UTF-8 encoding, you
cannot treat it as an EBCDIC string: for example, printing the string
will not produce displayable characters.
The "See Also" section below mentions some methods for obtaining
an EBCDIC serialization of an XmlDoc.
<li>You can use the Print method
(??[[Print (XmlDoc/XmlNode subroutine)|Print]])
to display a document on the terminal,
or to '''capture''' a displayable version of a document, but Print is
used to insert line breaks and optional indentation, which may not be an
accurate serialization of an XmlDoc.
<li>Using one of the line-end character options (CR, LF, CRLF) produces output
that is analogous to the BothCompact option of the Print method.
<li>If one of the line-end
(<tt>CR</tt>, <tt>LF</tt>, <tt>CRLF</tt>) options or if
<tt>Indent</tt> is specified, and an element to be serialized has the
<tt>xml:space="preserve"</tt> attribute, then
within the serialization of that element and its descendants, no line-end
(nor indentation) characters are inserted to provide readability.

In addition, the <tt>xml:space="default"</tt> attribute has no effect
under these options:
specified by itself, it does not influence serialization, nor
does it cause resumption of readability line-ends or indents if they were
suspended by a containing <tt>xml:space="preserve"</tt>.
<li>As of version 6.7, the Xml method uses the hexadecimal
character references specified in the XML Canonicalization specification
(:hp0 color=SirLink.http://www.w3.org/TR/xml-c14n:ehp0.)  to
display the following characters:
<ul>
<li>For Attribute nodes: tab, carriage return, and linefeed
<li>For Text nodes: carriage return
</ul>

Since the character references are not subject to the standard XML whitespace
normalization ([[??]] refid=normwhi.),
a serialized document (or subtree) that is then deserialized
will retain this whitespace.

These character references are used:
<dl>
<dt>tab
<dd>&amp;#x9;
<dt>CR
<dd>&amp;#xD;
<dt>LF
<dd>&amp;#xA;
</dl>

The EBCDIC and corresponding ASCII encodings of the characters is:
<dl>
<dt>&thinsp.
<dd>EBCDIC     ASCII
<dt>tab
<dd>X'05'           X'09'
<dt>CR
<dd>X'0D'           X'0D'
<dt>LF
<dd>X'25'           X'0A'
</dl>
<li>As of ''Sirius Mods'' version 7.6, ''Attribute values'' are always serialized
within double-quotation-mark (<tt>"</tt>) delimiters,
and a double-quotation mark character in an attribute value is serialized
as <tt>&amp;quot;</tt>.
Prior to version 7.6, this convention was not strictly observed.

</ul>
==Examples==
<ul>
<li>The [[Janus Sockets]]R documents the HttpRequest object, whose
AddXml method has nearly the same options as the Xml function;
the following fragment serializes an XmlDoc and sends it
as a request to a Web server.

Note that if you use the Xml function and $Sock_Send directly,
instead of using an HTTP helper object, always use
the BINARY option of $Sock_Send, because the
result of the
Xml function is UTF-8, rather than EBCDIC.
<p class="code">%httpreq object HttpRequest
%httpresp object HttpResponse
%doc object XmlDoc
%httpreq = New
%doc = New
%doc:LoadXml('<inquire><stock>IBM</stock>' With -
   <dateRange/></inquire>', 'NoEmptyElt')

%httpreq:URL = 'foo.com/bar'
%httpreq:AddXml(%doc)
%httpresp = %httpreq:Post('HTTP_CLIENT')
</p>
<li>The following fragment is a simple example for serializing an XmlDoc, which
could then, for example, be sent on a transport such as MQ:
<p class="code">%s Longstring
%s = %doc:Xml
</p>
</ul>

===Request-Cancellation Errors===
<ul>
<li>XmlDoc does not contain an Element.
<li><i>Options</i> is invalid.
<li>Insufficient free space exists in CCATEMP.
</ul>


==See also==
{{Template:XmlDoc:Xml footer}}

<ul>
<li>Use ??[[Print (XmlDoc/XmlNode subroutine)|Print]] to display an XML document for debugging.
<li>Use ??[[Serial (XmlDoc/XmlNode function)|Serial]] with the EBCDIC option to obtain an EBCDIC serialization of
an XML document.
<li>Use ??[[WebSend (XmlDoc subroutine)|WebSend]]
to serialize an XmlDoc and send it as an HTTP response using [[Janus Web Server]].
<li>The string deserialization functions are ??[[LoadXml (XmlDoc/XmlNode function)|LoadXml]]
and ??[[WebReceive (XmlDoc function)|WebReceive]].
</ul>