[mapguide-users] ODBC Point features failure

Mon Jul 9 09:17:27 EDT 2007

Hi Dave, 

I tried turning off the ODBC connection pooling - this has no affect - 
still times out after about 1 minute with that error message.    I will 
experiment with the various timeouts in mapguide and see if that helps. 

Meanwhile,   I am using the SQL Server ODBC driver, not the Native SQL 
Server driver - the latter cannot be used because of a problem identified 
by someone else recently - the Native driver has a problem reading SQL 
Server tables.   I was thinking that the Native driver may solve this 
issue, but it doesn't work at all.  Here's the error: 

<2007-07-06T16:37:40>                   Administrator
 Error: An exception occurred in FDO component.
        Invalid length 0 for column type VARCHAR, must be &gt; 0 
 StackTrace:
  - MgFeatureServiceHandler.ProcessOperation line 83 file 
c:\build_bond_area\mapguide_open_source_v1.2\build_18.1\mgdev\server\src\services\feature\FeatureServiceHandler.cpp
  - MgOpDescribeSchemaAsXml.Execute line 107 file 
c:\build_bond_area\mapguide_open_source_v1.2\build_18.1\mgdev\server\src\services\feature\OpDescribeSchemaAsXml.cpp
  - MgServerDescribeSchema.DescribeSchema line 500 file 
c:\build_bond_area\mapguide_open_source_v1.2\build_18.1\mgdev\server\src\services\feature\ServerDescribeSchema.cpp
  - MgServerDescribeSchema.ExecuteDescribeSchema line 173 file 
c:\build_bond_area\mapguide_open_source_v1.2\build_18.1\mgdev\server\src\services\feature\ServerDescribeSchema.cpp 
An exception occurred in FDO component.
Invalid length 0 for column type VARCHAR, must be &gt; 0 

This one does seem to be a mapguide bug - there are no tables in our 
schema which have a varchar length less than 10 - it seems not to be able 
to read the varchar type properly. 

Any ideas on this one? 

Thanks

Ian Elsinga

"Dave Wilson" <dave.wilson at autodesk.com> 
Sent by: mapguide-users-bounces at lists.osgeo.org
07/06/2007 12:50 PM
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RE: [mapguide-users] ODBC Point features failure

By default there are a series of timeouts that are set that could be 
affecting what you are seeing. Adjusting the timeouts completely depends 
on the behavior of the users.

For example as a developer working on a map you may want to significantly 
increase the timeout settings to allow connections to last for 20 min or 
more whereas a user on the production server may spend no more than 5 or 
10 min querying a map so holding connections for too long is a waste or 
can potentially not free up resources for other users.

Most of the default settings hold a session for about 20 min. So after you 
let your map sit for 20 min you will have to refresh it. However below the 
main timeout settings there is Connection Pooling taking place within FDO. 
These connections are held for 10 min (600 seconds) and then released. You 
may want to try and up this to 20 min to match the other timeouts. However 
in testing we have never seen the link failure error that I am aware of.

A communication link failure seems more like something external to FDO has 
dropped the connection rather than FDO dropping the connection. FDO is 
trying to use a connection that is no longer valid for some reason. Is 
there a proxy server or firewall or router in between your MapGuide server 
and your database server that could be dropping the connection? I’ve done 
some Google searches and one possibility is that your DSN has connection 
pooling enabled and it may be that the connection is dropped by SQLServer 
by the time you try to reuse it. It’s not clear yet if it’s actually a 
MapGuide bug.

The Google searches weren’t very informative. You might try to search msdn 
instead.

Dave

From: mapguide-users-bounces at lists.osgeo.org 
[mailto:mapguide-users-bounces at lists.osgeo.org] On Behalf Of 
IElsinga at fac.bm
Sent: Thursday, July 05, 2007 11:05 AM
To: MapGuide Users Mail List
Subject: RE: [mapguide-users] ODBC Point features failure

Hi Dave, thanks for the responses... 

I didn't know about the error log - there are indeed error messages like 
the following: 

<2007-07-05T13:54:45>                         fac 
 Error: Failed to stylize layer: Points 
        An exception occurred in FDO component. 
        RDBMS: [Microsoft][ODBC SQL Server Driver]Communication link 
failure 
 StackTrace: 
  - MgStylizationUtil.StylizeLayers line 923 file 
c:\build_bond_area\mapguide_open_source_v1.2\build_18.1\mgdev\server\src\services\mapping\StylizationUtil.cpp 
       Failed to stylize layer: Points 
An exception occurred in FDO component. 
RDBMS: [Microsoft][ODBC SQL Server Driver]Communication link failure 

Why would there be a Communications link failure?  We have lots of 
processes which communicate to that particular database continually.   It 
seems that something inside the FDO provider times out and it thinks it 
can no longer access SQL Server.   

If I restart the mapguide service and re-open the site, it initially 
works.  If I let it just sit there for a few minutes, without doing any 
zooming or panning or clicking, then when I try to zoom after that, the 
points disappear - and that error message above is in the error log.   So 
it seems that something in the FDO provider is timing out - it is allowing 
the connection to timeout perhaps and it doesn't re-establish it? 

Thanks for your help, 

Ian Elsinga

"Dave Wilson" <dave.wilson at autodesk.com> 
Sent by: mapguide-users-bounces at lists.osgeo.org 
07/05/2007 11:36 AM 

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RE: [mapguide-users] ODBC Point features failure

Are there any errors logged in the server error log? It seems to me 
something is causing the provider to die? Usually there is at least 1 
error logged before something like this can happen. 

What coordinate system is your data in and what coordinate system is your 
map in? 

Have you tried using the DWF Viewer/Autodesk Design Review? I’m curious if 
it’s the data or something in the viewer behavior. 

Regards, 
Dave 

"Dave Wilson" <dave.wilson at autodesk.com> 
Sent by: mapguide-users-bounces at lists.osgeo.org 
07/04/2007 06:47 PM 

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RE: [mapguide-users] ODBC Point features failure

In house testing with a feature source containing almost 10,000 features 
appears to work fine. 

How much memory on your system? What is the OS? Do you have properties 
selected on your layer? How many other layers are in your map? 

Regards, 
Dave 

From: mapguide-users-bounces at lists.osgeo.org 
[mailto:mapguide-users-bounces at lists.osgeo.org] On Behalf Of 
IElsinga at fac.bm
Sent: Wednesday, July 04, 2007 10:33 AM
To: mapguide-users at lists.osgeo.org
Subject: [mapguide-users] ODBC Point features failure 

I am using MGOS 1.2 RC2 and am experiencing a problem with an ODBC 
connected to SQL Server point source.    Points are displayed initially, 
but then eventually they are not displayed any longer.  Opening a new web 
browser does not help.  The only way I can get them to come back is to 
restart the MapGuide windows service - then the points will come back - 
for a few minutes of interaction.   

I am bringing back 1000 points from a SQL Server database.    This 
behaviour was the same in 1.2 RC1. 

This will obviously make mapguide unusable for our purposes - is there a 
problem with the ODBC FDO?   

I will be grateful for any assistance!   

Ian Elsinga_______________________________________________
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