Thank you for your response.
Actually I work on creating a SOE service for doing utility network analyst.
I want to get the network information like barriers, flags, disable layers , etc from the application and set them to my netsolver and solve the network base on these information. For accessing these information I need to access to NetAnalysisExt and for accessing this extention I need to access to application.In the other word, if I have access to application I can find the networkanalysisExt by CLSID like this code:
pID = new UID();
pID.Value = "esriEditorExt.UtilityNetworkAnalysisExt";
pNetAnalysisExt = (INetworkAnalysisExt)app.FindExtensionByCLSID(pID);
And then I can get barriers, flags, disable layers from pNetAnalysisExt and set to my netsolver and solve the network.
In addition, I try to use FindExtensionByCLSID of SOExtManager but it returns null value:
ESRI.ArcGIS.Carto.IMapServer3 mapServer = (ESRI.ArcGIS.Carto.IMapServer3)serverObjectHelper.ServerObject;
IServerObjectExtensionManager pSOExtManager = mapServer as IServerObjectExtensionManager;
INetworkAnalysisExt NetAnalysisExt = (INetworkAnalysisExt)pSOExtManager.FindExtensionByCLSID("UtilityNetworkAnalysisExt");
Maybe because the UtilityNetworkAnalysisExt in not a valid extension for ArcGIS Server.
So I try to find a way to access to application to get the NetAnalysisExt from that. If it is not accessible, any way that can help me to access to NetAnalysisExt can be very useful.