Server Activated ServicedComponent and Config Files

Yes, it is possible to specify a per-component application config when using a ServicedComponent with activation type set to Server Application. By default all Server Applications are sharing dllhost.exe.config located in %windir%\system32.  But there are cases when you need to have different configs for different Server Apps. For instance, an important scenario is to have component A using version 1.0 of .Net Framework and component B using version 1.1.

This can be achieved by setting the Application Root Directory for that component to point to a directory where you have two files: application.manifest and application.config. The manifest can be as simple as:

<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0">
</assembly>

The application.config will be your normal app config where you can put your specific settings for your component.

[Originally posted Oct 13, 2003]

Comments

• Anonymous
  December 28, 2003
  Hi Florin, this feature works only for winxp and win2k3. Do you know if exists something similar under win2k ?. Thanks.
• Anonymous
  January 02, 2004
  Paul - Unfortunately Win2K doesn't support per app config files because Win2K doesn't have Application Root Directory.
• Anonymous
  April 11, 2004
  Hi folrin, i've been trying this for some time and it just won't work, i have winXP prof, do i need to install service pack 2 for this to work? thanks
• Anonymous
  April 13, 2004
  The comment has been removed
• Anonymous
  May 17, 2004
  Under W2k3, the files can be renamed as <ServerApplicationName>.manifest and <ServerApplicationName>.config. Unfortunately this solution doesn't work under windows xp
• Anonymous
  May 30, 2004
  All out-of-process COM applications by default are executed using the %SystemRoot%System32dllhost.exe surrogate process. What this used to mean that calling System.Configuration.ConfigurationSettings.AppSettings[
• Anonymous
  August 03, 2004
  Hi i have similar problems
  I'm developing mmc SNAP-in in vb6 using snapin designer,
  snain needs to interact with database ,
  database interaction code is written in vb.net,
  
  to use that .net assembly i register it for COM interoperability, And it successfully run in vb form project , And all config file settings successfdully obtained when runnin vb6 project exe.
  Now i use that same vb.net assembly in snapin by registering for COM interoperability.
  ( Snapin creates .ocx file)
  Now when i load snapin in mmc, it woun't find any config file, even though i renamed app.config as dllhost.exe.config
  I'm using win2k
  Any type of help highly appreciated
• Anonymous
  April 25, 2005
  Hi there do you have any idea how to overcome the problem under the W2K environment any idea will be highly appreciated THNAKS
• Anonymous
  April 27, 2005
  For win2k I copied a code fragment that was suggested of ADVANCED DOTNET list.(I'm not sure from whom, and modified 4 lines of code)
  
  I post the source code because so maybe it can be useful to others. Basically all you have to do is inherit for ServicedComponentEx.
  
  Good luck!
  
  [AttributeUsage(AttributeTargets.Class)]
  public class ServicedComponentExProxyAttribute : ProxyAttribute, ICustomFactory
  {
  private ProxyAttribute _base;
  private Type currentType;
  static AppDomain appDomain = null;
  
  public ServicedComponentExProxyAttribute()
  {
  _base = (ProxyAttribute)typeof(ServicedComponent).GetCustomAttributes(typeof(ProxyAttribute),false)[0];
  }
  public override MarshalByRefObject CreateInstance(Type serverType)
  {
  return _base.CreateInstance(serverType);
  }
  public override RealProxy CreateProxy(ObjRef objRef,Type serverType,object serverObject,Context serverContext)
  {
  return _base.CreateProxy(objRef,serverType,serverObject,serverContext);
  }
  Assembly ResolveHelper(object o, ResolveEventArgs rargs)
  {
  if ( currentType.Assembly.FullName == rargs.Name )
  {
  return Assembly.LoadFrom(currentType.Assembly.Location);
  }
  else
  {
  return null;
  }
  }
  MarshalByRefObject ICustomFactory.CreateInstance(Type serverType)
  {
  if ( AppDomain.CurrentDomain.FriendlyName == "myappdomain" )
  {
  return ((ICustomFactory)_base).CreateInstance(serverType);
  }
  else
  {
  if ( appDomain == null )
  {
  System.AppDomainSetup appDomainSetup = new AppDomainSetup();
  appDomainSetup.ApplicationBase =
  Path.Combine(Path.GetPathRoot(serverType.Assembly.Location), Path.GetDirectoryName(serverType.Assembly.Location));
  appDomainSetup.ApplicationName = "complus";
  appDomainSetup.ConfigurationFile = serverType.Assembly.GetName().Name + ".exe.config";
  appDomain = AppDomain.CreateDomain("myappdomain",null,appDomainSetup);
  }
  ResolveEventHandler reh = new ResolveEventHandler(this.ResolveHelper);
  currentType = serverType;
  AppDomain.CurrentDomain.AssemblyResolve += reh;
  MarshalByRefObject mbr = (MarshalByRefObject)appDomain.CreateInstanceFromAndUnwrap(serverType.Assembly.Location,serverType.FullName);
  AppDomain.CurrentDomain.AssemblyResolve -= reh;
  currentType = null;
  return mbr;
  }
  }
  }
  [ServicedComponentExProxyAttribute]
  public class ServicedComponentEx : ServicedComponent
  {
  public ServicedComponentEx()
  {}
  }
• Anonymous
  July 26, 2005
  From http://blogs.msdn.com/florinlazar/archive/2003/12/04/41369.aspx:
  setting the Application Root Directory...
• Anonymous
  August 02, 2005
  The comment has been removed
• Anonymous
  August 17, 2005
  Or you could just call AppDomain.CurrentDomain.SetData("APP_CON- FIG_FILE", settingsFilePath);
  
  ...
• Anonymous
  August 28, 2006
  I spent far too much time on Friday trying to make log4net work in a COM+ application. Someone else had