We’ve never supported or tested with the native driver that I am aware of so I 
can’t help on that front.

 

I’m not sure how to tackle this since we don’t know the conditions to reproduce 
the original communication link failure error.

 

The following MS article may yield something:

 

http://support.microsoft.com/kb/827422/en-us

 

Are you using IP address or name to connect to the server? Is the port the 
default 1433? I assume your SQL Server is configured to listen on TCP/IP.

 

What version of MDAC is on your server? It’s supposed to be 2.8 in 2003.

 

If the timeout is really only a minute then that doesn’t match any MapGuide 
timeouts that I’m aware of.

 

Dave

 

From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED]
Sent: Monday, July 09, 2007 7:17 AM
To: MapGuide Users Mail List
Subject: RE: [mapguide-users] ODBC Point features failure

 


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" <[EMAIL PROTECTED]> 
Sent by: [EMAIL PROTECTED] 

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: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED]
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" <[EMAIL PROTECTED]> 
Sent by: [EMAIL PROTECTED] 

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" <[EMAIL PROTECTED]> 
Sent by: [EMAIL PROTECTED] 

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: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED]
Sent: Wednesday, July 04, 2007 10:33 AM
To: [email protected]
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!   


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