[Standards] Regarding capitalization of base64 type in Jabber-RPC (XEP-0009)

Gerard Maas gerard.maas at gmail.com
Tue Sep 27 13:59:15 UTC 2011

Hi all,

We are currently developing Jabber-RPC based interactions in a distributed

We use the base64 type to transmit binary data over the wire and we are
facing a compatibility issue between  client and server implementations:

The capitalization of the 'Base64' element seems to be inconsistent across
the different documents related to the standard.

The XEP-0009 document [1] provides a schema that describes Base64 with
capital 'B'. It also has a disclaimer saying:

"There is no official XML schema for XML-RPC. The main body of this schema
has been borrowed
from an unofficial schema representation contained in the book "Processing
XML With Java" by Elliotte Rusty Harold,
as located at:

That document [2] presents a DTD and an XSD as definitions for the XML-RPC

The DTD declares base64 in lowercase :

<!ELEMENT base64           (#PCDATA)>

While the schema declares Base64 in uppercase:

<xsd:element name="Base64"        type="xsd:base64Binary"/>

Also, while looking at the complete XSD type definition, "Base64" is the
only entry which does not follow the 'start with lowercase'  pattern
 observed in the rest of the type declarations:

<xs:element name="i4"            type="xs:int"/>
<xs:element name="int"           type="xs:int"/>
<xs:element name="string"        type="ASCIIString"/>
<xs:element name="double"        type="xs:decimal"/>
<xs:element name="Base64"        type="xs:base64Binary"/>
<xs:element name="boolean"       type="NumericBoolean"/>
<xs:element name="dateTime.iso8601" type="xs:dateTime"/>
<xs:element name="array"         type="ArrayType"/>
<xs:element name="struct"        type="StructType"/>

The question is: is "Base64"  (in uppercase) a typo in the schema or is it
the correct definition for it and must be respected by the implementations?

Many thanks,

Gerard Maas.

[1] http://xmpp.org/extensions/xep-0009.html
[2] http://www.ibiblio.org/xml/books/xmljava/chapters/ch02s05.html

Disclaimer: I joined the list to discuss this issue. My excuses if this has
been handled before, though I would appreciate the final conclusion of any
previous discussions.
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