Tooltip performance

[Trevor Wekel]

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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