How to embed xml in xml

Question

I need to embed an entire well-formed xml document within another xml document. However, I would rather avoid CDATA (personal distaste) and also I would like to avoid the parser that will receive the whole document from wasting time parsing the embedded xml. The embedded xml could be quite significant, and I would like the code that will receive the whole file to treat the embedded xml as arbitrary data.

The idea that immediately came to mind is to encode the embedded xml in base64, or to zip it. Does this sound ok?

I'm coding in C# by the way.

Answer 1

I would encode it in your favorite way (e.g. base64 or HttpServerUtility::UrlEncode, ...) and then embed it.

Answer 2

You could convert the XML to a byte array, then convert it to binary64 format. That will allow you to nest it in an element, and not have to use CDATA.

Answer 3

It seems that serialization is the recommended method.

Answer 4

The W3C-approved way of doing this is XInclude. There is an implementation for .Net at http://mvp-xml.sourceforge.net/xinclude/

Answer 5

Just a quick note, I have gone the base64 route and it works just fine but it does come with a stiff performance penalty, especially under heavy usage. We do this with document fragments upto 20MB and after base64 encoding they can take upwards of 65MB (with tags and data), even with zipping.

However, the bigger issue is that .NET base64 encoding can consume up-to 10x the memory when performing the encoding/decoding and can frequently cause OOM exceptions if done repeatedly and/or done on multiple threads.

Someone, on a similar question recommended ProtoBuf as an option, as well as Fast InfoSet as another option.

Answer 6

Depending on how you construct the XML, one way is to not care about it and let the framework handle it.

XmlDocument doc = new XmlDocument(); 
doc.LoadXml("<?xml version=\"1.0\" encoding=\"utf-8\" ?><helloworld></helloworld>");
string xml = "<how><are><you reply=\"i am fine\">really</you></are></how>";
doc.GetElementsByTagName("helloworld")[0].InnerText = xml;

The output will be something like a HTMLEncoded string:

<?xml version="1.0" encoding="utf-8"?>
<helloworld>&lt;how&gt;&lt;are&gt;&lt;you
  reply="i am fine"&gt;really&lt;/you&gt;&lt;/are&gt;&lt;/how&gt;
</helloworld>

Answer 7

If you don't need the xml declaration (first line of the document), just insert the root element (with all childs) into the tree of the other xml document as a child of an existing element. Use a different namespace to seperate the inserted elements.

Answer 8

I use Comments for this :

<!-- your xml text -->

[EDITED]
If the embedded xml with comments, replace it with a different syntax.

<?xml version="1.0" encoding="iso-8859-1" ?>
<xml>
    <status code="0" msg="" cause="" />
    <data>
        <order type="07" user="none" attrib="..." >
        <xmlembeded >
            <!--
                <?xml version="1.0" encoding="iso-8859-1" ?>
                <xml>
                <status ret="000 "/>
                <data>
                <allxml_here />
                <!** embedeb comments **>
                </data>
                <xml>
            -->
        </xmlembeded >
        </order>
        <context sessionid="12345678" scriptname="/from/..."  attrib="..." />
    </data>
</xml>

Answer 9

Can't you use XSLT for this? Perhaps using xsl:copy or xsl:copy-of? This is what XSLT is for.