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Subject: [ebxml-msg] Issue73: http://schemas.xmlsoap.org/soap/envelopenamespace

While writing my previous email (on issue 56) to Dick, I recognised an assumption not supported in the document (I think).  I've been assuming the receiver MUST (at least SHOULD) validate a message against the ebXML Messaging schema.  If that's not supported by our documentation and the SOAP envelope schema, we're in a whole world of security hurt.  (Just for example, code is often written assuming something is in the DOM tree because the schema requires its presence.  That code fails in ugly ways when those assumptions are violated by an non validating XML parser.)  Due to the changes currently proposed resolving issue 73, I don't think we have the assurance of XML validation if we ever did in the past.
Two things determine whether or not an XML instance is validated against a schema.  First, the parser responsible for reading the instance must be configured to perform validation.  I don't recall whether or not SOAP requires such a parser configuration.  Second, the specific elements of interest must be declared within a processContents="strict" block.  Without strict interpretation of the block, a validating parser MAY or MUST (depending on the precise declaration) skip the block.
The schema found at [1] does not match our hacked version at [2] in one important way: The one we threw together for our own use required validation of the SOAP extension elements found in the Envelope and Header.  [2] instead uses processContents="lax".  This means a validating parser MAY skip the contents of the Header and Envelope elements.
[1] http://schemas.xmlsoap.org/soap/envelopenamespace
[2] http://www.oasis-open.org/committees/ebxml-msg/schema/envelope.xsd
To make the suggested change to our msg-header.xsd file, we must change the document in a few more ways than previously suggested.  In addition to removing mention of our specific schema location for the SOAP namespace, we must STRONGLY RECOMMEND the XML parser be configured to interpret processContents="lax" as processContents="strict".   (I'd prefer MUST to avoid long sentences describing requirements in this area for any level of security assurance.)  If the SOAP specification doesn't do this for us already, we should also require the XML parser to validate received documents.

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