WMS provider hangs for 2 minutes for unavailable request

[ChristineBao]

Reported from Autodesk Customer: He uses MapGuide to connect to WMS server and create maps. Sometimes the WMS server is not stable, it can deals with GetCapabilities request, but cannot respond to GetMap request. The customer complains that the map will hands up for minutes if WMS is offline, and he wants quicker return in this case.

[ChristineBao]

Tech Assessment WMS blocks for return from server till 2 minutes timeout. FdoOwsDelegate.cpp shows:

    FdoPtr<FdoOwsHttpHandler> httpHandler = FdoOwsHttpHandler::Create(mbUrl, bGet, mbRequestString, mbUserName, mbPasswd, mbProxyHost, mbProxyPort, mbProxyUserName, mbProxyPassword);
        
    // Here we use 2 mins as the default value for "connection" timeout.
    httpHandler->SetConnectionTimeout (60 * 2);

    // The Perform call won't return util beginning receiving http content.
    // If there are any connection related problems, exceptions
    // thrown out here
    httpHandler->Perform();

The hard-coded timeout value should be pulled outside so that user can configure it according to their needs. FDO connection has a capability SupportsTimeout(), and Get/SetConnectionTimeout(). So they can be used to config the time out value for WMS provider.

[ChristineBao]

Attach ​http://trac.osgeo.org/fdo/attachment/ticket/772/FDO_WMSTimeout.patch for review.

Some note:

1. The default timeout value for OWS is 120 seconds. If user does not set ConnectionTimeout, the default value is still 120 seconds.
2. Currently no provider supports timeout, so after the fixing only WMS provider is affected and can use ConnectionTimeout.

[ChristineBao]

Related ticket in MapGuide ​http://trac.osgeo.org/mapguide/attachment/ticket/1793/.

[ChristineBao]

Submit r6219 in trunk to fix this ticket.

[ChristineBao]

Submit r6340 to integrate the fix to Reeses SP2.