Modifying Web.Config handlers section generates extra unneeded entries

Question

I've written a command line tool that deploys HTTP Handlers to an applications Web.Config file using a combination of System.Configuration, System.Web.Configuration and Microsoft.Web.Administration since it needs to register the handlers for both Classic and Integrated Modes as I don't know what mode end users will be using for their IIS deployments.

My issue is that is that when the tool is run the <handlers> section under <system.webServer> gets filled with the following extra unecessary entries as well as the entries I wanted to add:

<add name="rules-Integrated" path="*.rules" verb="*" type="System.ServiceModel.Activation.HttpHandler, System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" preCondition="integratedMode" />
<add name="xoml-Integrated" path="*.xoml" verb="*" type="System.ServiceModel.Activation.HttpHandler, System.ServiceModel, Version=3.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" preCondition="integratedMode" />
<add name="ISAPI-dll" path="*.dll" verb="*" modules="IsapiModule" resourceType="File" requireAccess="Execute" allowPathInfo="true" />
<add name="TraceHandler-Integrated" path="trace.axd" verb="GET,HEAD,POST,DEBUG" type="System.Web.Handlers.TraceHandler" preCondition="integratedMode" />
<add name="WebAdminHandler-Integrated" path="WebAdmin.axd" verb="GET,DEBUG" type="System.Web.Handlers.WebAdminHandler" preCondition="integratedMode" />
<add name="AssemblyResourceLoader-Integrated" path="WebResource.axd" verb="GET,DEBUG" type="System.Web.Handlers.AssemblyResourceLoader" preCondition="integratedMode" />
<add name="PageHandlerFactory-Integrated" path="*.aspx" verb="GET,HEAD,POST,DEBUG" type="System.Web.UI.PageHandlerFactory" preCondition="integratedMode" />
<add name="SimpleHandlerFactory-Integrated" path="*.ashx" verb="GET,HEAD,POST,DEBUG" type="System.Web.UI.SimpleHandlerFactory" preCondition="integratedMode" />
<add name="WebServiceHandlerFactory-Integrated" path="*.asmx" verb="GET,HEAD,POST,DEBUG" type="System.Web.Services.Protocols.WebServiceHandlerFactory, System.Web.Services, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" preCondition="integratedMode" />
<add name="HttpRemotingHandlerFactory-rem-Integrated" path="*.rem" verb="GET,HEAD,POST,DEBUG" type="System.Runtime.Remoting.Channels.Http.HttpRemotingHandlerFactory, System.Runtime.Remoting, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" preCondition="integratedMode" />
<add name="HttpRemotingHandlerFactory-soap-Integrated" path="*.soap" verb="GET,HEAD,POST,DEBUG" type="System.Runtime.Remoting.Channels.Http.HttpRemotingHandlerFactory, System.Runtime.Remoting, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" preCondition="integratedMode" />
<add name="CGI-exe" path="*.exe" verb="*" modules="CgiModule" resourceType="File" requireAccess="Execute" allowPathInfo="true" />
<add name="rules-ISAPI-2.0" path="*.rules" verb="*" modules="IsapiModule" scriptProcessor="C:\Windows\Microsoft.NET\Framework\v2.0.50727\aspnet_isapi.dll" requireAccess="Script" preCondition="classicMode,runtimeVersionv2.0,bitness32" />
<add name="rules-64-ISAPI-2.0" path="*.rules" verb="*" modules="IsapiModule" scriptProcessor="C:\Windows\Microsoft.NET\Framework64\v2.0.50727\aspnet_isapi.dll" requireAccess="Script" preCondition="classicMode,runtimeVersionv2.0,bitness64" />
<add name="xoml-ISAPI-2.0" path="*.xoml" verb="*" modules="IsapiModule" scriptProcessor="C:\Windows\Microsoft.NET\Framework\v2.0.50727\aspnet_isapi.dll" requireAccess="Script" preCondition="classicMode,runtimeVersionv2.0,bitness32" />
<add name="xoml-64-ISAPI-2.0" path="*.xoml" verb="*" modules="IsapiModule" scriptProcessor="C:\Windows\Microsoft.NET\Framework64\v2.0.50727\aspnet_isapi.dll" requireAccess="Script" preCondition="classicMode,runtimeVersionv2.0,bitness64" />
<add name="ASPClassic" path="*.asp" verb="GET,HEAD,POST" modules="IsapiModule" scriptProcessor="%windir%\system32\inetsrv\asp.dll" resourceType="File" />
<add name="SecurityCertificate" path="*.cer" verb="GET,HEAD,POST" modules="IsapiModule" scriptProcessor="%windir%\system32\inetsrv\asp.dll" resourceType="File" />
<add name="AXD-ISAPI-2.0-64" path="*.axd" verb="GET,HEAD,POST,DEBUG" modules="IsapiModule" scriptProcessor="%windir%\Microsoft.NET\Framework64\v2.0.50727\aspnet_isapi.dll" requireAccess="Script" preCondition="classicMode,runtimeVersionv2.0,bitness64" responseBufferLimit="0" />
<add name="PageHandlerFactory-ISAPI-2.0-64" path="*.aspx" verb="GET,HEAD,POST,DEBUG" modules="IsapiModule" scriptProcessor="%windir%\Microsoft.NET\Framework64\v2.0.50727\aspnet_isapi.dll" requireAccess="Script" preCondition="classicMode,runtimeVersionv2.0,bitness64" responseBufferLimit="0" />
<add name="SimpleHandlerFactory-ISAPI-2.0-64" path="*.ashx" verb="GET,HEAD,POST,DEBUG" modules="IsapiModule" scriptProcessor="%windir%\Microsoft.NET\Framework64\v2.0.50727\aspnet_isapi.dll" requireAccess="Script" preCondition="classicMode,runtimeVersionv2.0,bitness64" responseBufferLimit="0" />
<add name="WebServiceHandlerFactory-ISAPI-2.0-64" path="*.asmx" verb="GET,HEAD,POST,DEBUG" modules="IsapiModule" scriptProcessor="%windir%\Microsoft.NET\Framework64\v2.0.50727\aspnet_isapi.dll" requireAccess="Script" preCondition="classicMode,runtimeVersionv2.0,bitness64" responseBufferLimit="0" />
<add name="HttpRemotingHandlerFactory-rem-ISAPI-2.0-64" path="*.rem" verb="GET,HEAD,POST,DEBUG" modules="IsapiModule" scriptProcessor="%windir%\Microsoft.NET\Framework64\v2.0.50727\aspnet_isapi.dll" requireAccess="Script" preCondition="classicMode,runtimeVersionv2.0,bitness64" responseBufferLimit="0" />
<add name="HttpRemotingHandlerFactory-soap-ISAPI-2.0-64" path="*.soap" verb="GET,HEAD,POST,DEBUG" modules="IsapiModule" scriptProcessor="%windir%\Microsoft.NET\Framework64\v2.0.50727\aspnet_isapi.dll" requireAccess="Script" preCondition="classicMode,runtimeVersionv2.0,bitness64" responseBufferLimit="0" />
<add name="AXD-ISAPI-2.0" path="*.axd" verb="GET,HEAD,POST,DEBUG" modules="IsapiModule" scriptProcessor="%windir%\Microsoft.NET\Framework\v2.0.50727\aspnet_isapi.dll" requireAccess="Script" preCondition="classicMode,runtimeVersionv2.0,bitness32" responseBufferLimit="0" />
<add name="PageHandlerFactory-ISAPI-2.0" path="*.aspx" verb="GET,HEAD,POST,DEBUG" modules="IsapiModule" scriptProcessor="%windir%\Microsoft.NET\Framework\v2.0.50727\aspnet_isapi.dll" requireAccess="Script" preCondition="classicMode,runtimeVersionv2.0,bitness32" responseBufferLimit="0" />
<add name="SimpleHandlerFactory-ISAPI-2.0" path="*.ashx" verb="GET,HEAD,POST,DEBUG" modules="IsapiModule" scriptProcessor="%windir%\Microsoft.NET\Framework\v2.0.50727\aspnet_isapi.dll" requireAccess="Script" preCondition="classicMode,runtimeVersionv2.0,bitness32" responseBufferLimit="0" />
<add name="WebServiceHandlerFactory-ISAPI-2.0" path="*.asmx" verb="GET,HEAD,POST,DEBUG" modules="IsapiModule" scriptProcessor="%windir%\Microsoft.NET\Framework\v2.0.50727\aspnet_isapi.dll" requireAccess="Script" preCondition="classicMode,runtimeVersionv2.0,bitness32" responseBufferLimit="0" />
<add name="HttpRemotingHandlerFactory-rem-ISAPI-2.0" path="*.rem" verb="GET,HEAD,POST,DEBUG" modules="IsapiModule" scriptProcessor="%windir%\Microsoft.NET\Framework\v2.0.50727\aspnet_isapi.dll" requireAccess="Script" preCondition="classicMode,runtimeVersionv2.0,bitness32" responseBufferLimit="0" />
<add name="HttpRemotingHandlerFactory-soap-ISAPI-2.0" path="*.soap" verb="GET,HEAD,POST,DEBUG" modules="IsapiModule" scriptProcessor="%windir%\Microsoft.NET\Framework\v2.0.50727\aspnet_isapi.dll" requireAccess="Script" preCondition="classicMode,runtimeVersionv2.0,bitness32" responseBufferLimit="0" />
<add name="SSINC-stm" path="*.stm" verb="GET,POST" modules="ServerSideIncludeModule" resourceType="File" />
<add name="SSINC-shtm" path="*.shtm" verb="GET,POST" modules="ServerSideIncludeModule" resourceType="File" />
<add name="SSINC-shtml" path="*.shtml" verb="GET,POST" modules="ServerSideIncludeModule" resourceType="File" />
<add name="AboMapperCustom-159838" path="*.pl" verb="GET,HEAD,POST" modules="CgiModule" scriptProcessor="C:\Perl64\bin\perl.exe &quot;%s&quot; %s" resourceType="File" requireAccess="Script" responseBufferLimit="0" />
<add name="TRACEVerbHandler" path="*" verb="TRACE" modules="ProtocolSupportModule" requireAccess="None" />
<add name="OPTIONSVerbHandler" path="*" verb="OPTIONS" modules="ProtocolSupportModule" requireAccess="None" />
<add name="StaticFile" path="*" verb="*" modules="StaticFileModule,DefaultDocumentModule,DirectoryListingModule" resourceType="Either" requireAccess="Read" />

Does anyone know why this might be happening and how I can stop it?

When I save my configuration opened with System.Web.WebConfigurationManager I use ConfigurationSaveMode.Minimal so any inherited configuration (which is what this appears to be) should not get written.

Strangely enough if this is then deleted on subsequent runs of the program this information does not reappear

Any ideas/pointers/solutions?

Answer 1

You are probably using Microsoft.Web.Administration, in the code that adds the handler try specifying the index (AddAt) 0 (or -1? I do not remember exactly), but that should prevent that from happening. The reason is because that collection uses semantics of appending the new ones at the top and since you are just calling Add then it forces it to add a copy of the parent to "obey" your code.