XML DOM parser raises error on namespaces due to coding error

X-NODEREF or X-DOCUMENT SAVE raise error "Attempt to re-declare namespace" or similar, if ABL code tries to declare different URNs for default namespace. This is especially likely to happen when using CREATE-NODE-NAMESPACE method and adding 'xmlns' attributes via SET-ATTRIBUTE at the same time.

Sep 17, 2019
Knowledge

Title

URL Name

XML-DOM-parser-raises-error-on-namespaces-due-to-coding-error

Article Number

000180871

Environment

Product: OpenEdge Version: 10.2B, 11.x, 12.x OS: All supported platforms Other: XML,

Question/Problem Description

Code creates XML documents via DOM parser (X-DOCUMENT, X-NODEREF objects)
Migrating code to newer OpenEdge release, it starts raising error
"X-NODEREF or X-DOCUMENT SAVE got an error: Attempt to re-declare namespace prefix '' for namespace '<name 1>' in element '<element>'. It is already declared for namespace '<name 2>'. (9082)" (in OE 10.2B) or
"X-NODEREF or X-DOCUMENT SAVE got an error: An attempt is made to create or change an object in a way which is incorrect with respect to namespaces. (9082)" (in OE 11.6.x)

Steps to Reproduce

Clarifying Information

Code worked in releases before 10.2B.

Error (9082) is a placeholder message, the actual error text comes from the XML parser embedded in the AVM. The different error texts are a result of different versions of the parser being used in different OpenEdge releases.

Error Message

X-NODEREF or X-DOCUMENT SAVE got an error: Attempt to re-declare namespace prefix '' for namespace '<name 1>' in element '<element>'. It is already declared for namespace '<name 2>'. (9082) (older OE releases) X-NODEREF or X-DOCUMENT SAVE got an error: An attempt is made to create or change an object in a way which is incorrect with respect to namespaces. (9082) (current OE releases)

Defect Number

Enhancement Number

Cause

Due to coding error, there is indeed a conflict in namespace declarations for the default namespace.

Example 1.:

DEFINE VARIABLE hDoc  AS HANDLE   NO-UNDO.
DEFINE VARIABLE hRoot AS HANDLE   NO-UNDO.
DEFINE VARIABLE lcXML AS LONGCHAR NO-UNDO.


CREATE X-DOCUMENT hdoc.
CREATE X-NODEREF hRoot.
hDoc:CREATE-NODE-NAMESPACE(hRoot, "defaultnamespace", "Order", "ELEMENT").
hDoc:APPEND-CHILD(hRoot).
hRoot:SET-ATTRIBUTE("xmlns", "othernamespace").
hdoc:SAVE ("longchar",lcXML).

DELETE OBJECT hroot.
DELETE OBJECT hdoc.

Example 2.:

DEFINE VARIABLE hDoc AS HANDLE NO-UNDO.
DEFINE VARIABLE hItem AS HANDLE NO-UNDO.
    
CREATE X-DOCUMENT hDoc.
CREATE X-NODEREF hItem.
    
hDoc:CREATE-NODE-NAMESPACE(hItem, 'http://your_URL','siiLR:_some_thing_','element').
hItem:SET-ATTRIBUTE('xmlns:siiLR', 'http://different_URL').

hDoc:APPEND-CHILD(hItem).

hDoc:SAVE("file","test.xml").

DELETE OBJECT hItem. 
DELETE OBJECT hDoc.

The CREATE-NODE-NAMESPACE() method will add a namespace to the default namespace (with blank prefix). The SET-ATTRIBUTE() method, by adding an xmlns attribute without namespace prefix, attempts to do the same, but with a different URN.
This is invalid according to XML standards - a namespace may be declared multiple times, but if that is done it must use the same URN at all times.

This is expected behavior.
OpenEdge releases prior to 10.2B may have allowed the code above to run without error, but that is due to defects -> failing to enforce XML standards.

Resolution

When redeclaring the namespace, make sure the same URN is used at all times.

Alternatively, avoid re-declaring the default namespace where possible.
Either use CREATE-NODE() instead of CREATE-NODE-NAMESPACE() or remove the SET-ATTRIBUTE("xmlns",...) statements.

Workaround

Notes

Keyword Phrase

Last Modified Date

9/17/2019 10:15 AM

XML DOM parser raises error on namespaces due to coding error

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