FOLLOWUP: [mapguide-internals] DBXML upgrade for MapGuide 2.3

[Steve Dang]

Hi Andreas,

MapGuide extensively uses MgByteReader::ToStringUtf8 which has not been changed for a long while. So, if there is a problem with it, then we'd better fix it.

By comparing 2.3.10 and 2.5.16, I saw the implementation of XmlDocument::setContent(const std::string &content) has been changed. Perhaps, debugging into this method may help find the problem (there was some problem with this method in the past).

I assume this new problem exists in both 32 and 64 bit environments.

Thanks,
Steve.

-----Original Message-----
From: mapguide-internals-bounces at lists.osgeo.org [mailto:mapguide-internals-bounces at lists.osgeo.org] On Behalf Of Andreas Morf
Sent: Saturday, June 12, 2010 8:04 AM
To: 'MapGuide Internals Mail List'
Subject: FOLLOWUP: [mapguide-internals] DBXML upgrade for MapGuide 2.3

Hi all,
I have a running mgserver (from trunk) using dbxml-2.5.16, geos-3.2.2 which
I set up because of the strange  behaviour described in ticket 1376
(trac.osgeo.org/mapguide/ticket/1376).

Besides several small fixes which are caused by xerces update to v3 a
strange malfunction interrupted my work for quite a few time:

When running mgserver on emtpy/new repositories the new dbxml-files are
created, but all the documents in the site repository were available but
empty (preconfigured users, roles...)
After some investigations i found a place to correct this behaviour:

In MgDev\Server\src\Services\Resource\ResourceContentManager.cpp at line 175
the content is added to the xmlDoc to store:

    xmlDoc.setContent(document);

    // Add the resource content.

    XmlUpdateContext updateContext = xmlMan.createUpdateContext();

    PutDocument(resource, xmlDoc, updateContext);

If adding the following statement before that:

    std::string cont = std::string(document);

and using 'setContent(cont);' instead, everything works ok (so the
copy-constructor created a suitable string).

So it seems that the 'const string& document' which is created with
'content->ToStringUtf8(contentDoc);' from a MgByteReadre is not in a correct
state...
Also it is strange that 'cout << document' is resulting with reasonable
output to the screen...

Any idea about how and where to find the source of the problem?

Andreas


-----Ursprüngliche Nachricht-----
Von: mapguide-internals-bounces at lists.osgeo.org
[mailto:mapguide-internals-bounces at lists.osgeo.org] Im Auftrag von Rohit
Razdan
Gesendet: Freitag, 11. Juni 2010 21:25
An: MapGuide Internals Mail List
Betreff: [mapguide-internals] DBXML upgrade for MapGuide 2.3

Hi all,
As part of my GSOC project I have been attempting to make the
build/installation experience of MapGuide better on Linux. As part of this
attempt, I have been trying to use 'native' 3rd party OEMs where possible
and this mail is with regards to DBXML.

The version we are using right now is DBXML 2.3.10 with xerces 2.7. The
latest version is 2.5.16 compiled with Xerces 3.0.1 but requires Xerces
above 2.7.[1] MapGuide also uses Xerces sources and the code breaks if
Xerces is upgraded to anything above 2.7 (a summary of changes is at [2]).
Xerces is already an installable package on Ubuntu and there has been talk
of including DBXML as well. On CentOS, Xerces 2.7 is available. But DBXML is
not an installable package on Ubuntu or CentOS.

Now ideally we would want our user to install Xerces from the standard
repos, build/install DBXML ( I plan on creating rpm/debs for it ) and
build/install MapGuide independently from its dependencies.  But this would
involve updating the code base to the new standards. I am working on the
changes now and right now the changes *appear* to be not so major. The
issues I have faced till now [3] are only from the changes in Xerces but it
is entirely possible that upgrading from DBXML 2.3 to DBXML 2.5 would bring
its own changes.

So the options that we have right now are:-

   - Upgrade to DBXML 2.5 along with the latest Xerces. This would be a step
   in our aim of making MapGuide installation easy and standard.
   - Upgrade to DBXML 2.5 but retain Xerces 2.7 . This would be counter
   intuitive to our stated goals of independent 3rd part dependencies
   installation. In fact given that Xerces is available as a package, it
makes
   more sense to upgrade Xerces first.
   - Upgrade to DBXML 2.4 which uses Xerces 2.8. This also breaks the code,
   but the fix appears to be pretty easy. Just including a header file that
was
   previously automatically included. [3]
   - Package current DBXML 2.3 as an rpm/deb and continue to use Xerces 2.7.

Rohit

LINKS
[1]
http://www.oracle.com/technology/software/products/berkeley-db/xml/index.htm
l.DBXML
download and changelog info.
[2] http://xerces.apache.org/xerces-c/migrate-archive-3.html . (Xerces
migration issue list)
[3] As part of a very preliminary look, the errors I have seen till now are
related to

   - "When using SAX2, including XMLReaderFactory to use createXMLReader
   doesn't include xercesc/parsers/SAX2XMLReaderImpl.hpp anymore."
   - "A number of DOM interfaces (DOMBuilder, DOMWriter, DOMInputSource,
   etc.) were replaced as part of the the final DOM Level 3 specification
   conformance work."

Of course more are to be expected. I am not familiar enough with the source
as of now.
_______________________________________________
mapguide-internals mailing list
mapguide-internals at lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/mapguide-internals

_______________________________________________
mapguide-internals mailing list
mapguide-internals at lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/mapguide-internals