[mapguide-users] RE: Tooltip performance

[Andy Morsell]

Why is each FeatureSource for each layer queried when it is only the
top-most layer in the display priority that should display the tooltip?
 

Andy 


  _____  

From: Trevor Wekel [mailto:trevor.wekel at autodesk.com] 
Sent: Friday, November 17, 2006 9:54 AM
To: Campbell, Keith A; users at mapguide.osgeo.org
Subject: [mapguide-users] RE: Tooltip performance


Hi Keith,
 
You are correct with the basic flow of events for generating the tooltips.
The AJAX client sends the map coordinates of the point along with the map
name to the Web Extensions.  The Web Extensions in turn, forwards this
information to the Server.  Once at the server, all of the layers in the map
are queried to see if they have any features underneath the point.  Since
every layer is queried, the performance will depend on the number of layers
in the Map.  Each FeatureSource for each layer will be queried.  If you have
a number of layers from external databases, the database will be queried for
each layer.
 
Feature Service connection pooling and caching may help.  These are
controlled by the following settings in serverconfig.ini and should be
accessible from Server Admin.
 
[FeatureServiceProperties]
DataConnectionPoolSize = 20
DataConnectionPoolExcludedProviders = OSGeo.SDF,OSGeo.SHP
DataConnectionPoolEnabled = 1
DataCacheSize = 100
CacheSize = 100
 
Just as a side note, I think MapGuide 6.x handles tooltip generation client
side.  I don't think it goes back to the server so it will be less affected
by server load.
 
Thanks,
Trevor

  _____  

From: Campbell, Keith A [mailto:keith.campbell at atkinsglobal.com] 
Sent: Friday, November 17, 2006 6:53 AM
To: users at mapguide.osgeo.org
Subject: Tooltip performance



I'm finding that the performance of the tooltips is varying greatly and I'd
like to understand what is going on behind the scenes and therefore what
factors are affecting this.

Presumably when the cursor s moved over the map, a mouseover event is
triggered and this sends the position information and state of the layers is
sent back to the server via an xmlhttprequest. The web extensions are used
to identify what object on what layer is at the map location, and the
tooltip data is queried and returned to the client, which is then displayed.
So factors affecting this process will be what is happening on the client
machine, the network, and the server at the time the process occurs.

The performance seems to change a great deal from very good to unacceptably
slow (the user would give up). I find this change strange because other
applications (e.g. MapGuide 6.x) run from the same client to the same server
are not varying nearly as much. It is also strange in that the initial
request for the layout and subsequent requests for layer data are not
particularly slow when the tooltips are. Are there any settings which can be
altered to improve this? This kind of unreliability could almost rule this
technology out in my view.

Keith 



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