[mapguide-users] ODBC Point features failure

Fri Jul 6 11:50:47 EDT 2007

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 FDO is trying to use a connection that is no longer valid for some reason.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> 
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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 

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 6:25 AM
To: MapGuide Users Mail List
Cc: MapGuide Users Mail List; mapguide-users-bounces at lists.osgeo.org
Subject: RE: [mapguide-users] ODBC Point features failure 

I noticed that when it stops working, there are no more SQL statements being sent to the database.  (Discovered by using SQL Profiler).   

Ian Elsinga
Senior Client/Server Application Developer
First Atlantic Commerce
Bermuda

mailto:ielsinga at fac.bm
Phone : (441) 294-4640
Primary Fax : (441) 295-6855 
Secondary Fax : (441) 295-6708

http://www.firstatlanticcommerce.com

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IElsinga at fac.bm 
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07/05/2007 09:15 AM 

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RE: [mapguide-users] ODBC Point features failure

Thanks for the response - there is 4GB of RAM on the mapguide server which is running Windows Server 2003.  There are no properties selected and there are only two layers.   It is pulling data via ODBC from SQL Server on another server which is configured similarly.   

I can use the map for a few minutes, zooming, panning, clicking on points, etc., but then the points disappear for no reason and the only way I can get them back is to restart the mapguide service.   

Is this a bug I should report somewhere? 

Thanks, 

Ian Elsinga
Senior Client/Server Application Developer
First Atlantic Commerce
Bermuda

mailto:ielsinga at fac.bm
Phone : (441) 294-4640
Primary Fax : (441) 295-6855 
Secondary Fax : (441) 295-6708

http://www.firstatlanticcommerce.com

---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
The information in this Internet e-mail, including attachments, contains information that is confidential and may be protected by attorney client privileges. This email, including attachments, constitutes non-public information intended only for the use of the designated recipient(s) to which it is addressed and may contain legal or financial information which is privileged, confidential or subject to copyright. Access by any other person to this Internet e-mail is not authorized. If you are not the intended recipient, please delete this Internet e-mail, including attachments, immediately and notify the sender by return email. Any disclosure of this Internet e-mail, including attachments, or of the parties to it, or copying, distribution or any action taken or omitted to be taken in reliance on it is prohibited, and may be unlawful.

"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!   

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