Windows Service Administration with ASP.NET – Part 2 – Remoting to the Marshalled Object

Posted by Brendan Tompkins on November 13, 2003

Yesterday, I posted Windows Service Administration with ASP.NET – Part 1 – Marshalling Status Information to
show how to Marshal an object from a Windows Service to for monitoring
from an ASP.NET control.  Here’s how to remote to it and use it
from an ASCX control.

Step 1:  Add a method to
Activate the remotable object, and return the inner class. I’ve
implemented this in a Business-tier class, but you can put this code
directly in your .ascx control if you wish.

public WatchListStatus GetCurrentStatus()
{
  try
  {
     // Call GetObject to Activate our Remotable object
     WatchListStatusRemotable wlsr = (WatchListStatusRemotable) Activator.GetObject(
          typeof(WatchListStatusRemotable), “tcp://[SERVER]:8001/GateStatus”);

     // Return the inner class that contains the monitoring info
     return wlsr.ServiceStatus;
  }
  catch(System.Exception ex)
  {
      System.Diagnostics.Trace.WriteLine(ex);
      System.Diagnostics.Trace.WriteLine(ex.InnerException);
      return null;
   }
}

Step 2: … Is so simple, I’m not
sure I even need to explain it.  Just call your Get method, and do
whatever you want with your remote object. 

WatchListStatus status = GetCurrentStatus();

foreach(WatchListStatusItem item in status.StatusHistory)
{
  // … Do some cool stuff with your remote object here and amaze your friends.
}

Part 3 – Controlling your Service. 

-Brendan

Music Tip – Explore a good Record Label, Like Candle Records

About Brendan Tompkins

Brendan runs CodeBetter.Com and Devlicio.Us. He is a former MVP for Microsoft .NET and is president of Port Technology Services, a partner with Port Solution Integrators a provider of hardware and software integration services for the transportation and logistics industry.
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  • http://www.mymailmarket.be myMailMarket

    Thanks Brendan, for our myMailMarket e-marketing tool we needed to have an admin page to control all running background services. This is just what we were looking for!

    Thx from the guys of http://www.mymailmarket.be

  • Charlie

    Here is more detail on the problem Im having:

    I have a service which periodically pings a remote IP address to determine connectivity. When connectivity is dropped or restored, I want to know the duration of the downtime, so I have a couple of classes storing that data.

    I need to be able to remotely query the object which is storing that data, so your code is a big help (if I can get it to go).

    Here is the server code which mashalls the object Im trying to use remotely (In OnStart):
    // Register the TCP Channel on port 8001
    ChannelServices.RegisterChannel(new TcpChannel(8001));

    // Register the type
    RemotingConfiguration.RegisterWellKnownServiceType (
    typeof(ConnectionStateRemotable),
    “cConnectionStateChanges”,
    WellKnownObjectMode.Singleton);

    // Now, Marshal it this will make it available to other processes via the TCP remoting channel
    try
    {
    RemotingServices.Marshal(m_ConnectionStatus, “cConnectionStateChanges”);
    eventLog1.WriteEntry(“cConnectionStateChanges Marshalled”);
    }
    catch (System.Exception ex)
    {
    eventLog1.WriteEntry(ex.Message);
    eventLog1.WriteEntry(ex.InnerException.Message );
    }

    The object does get marshalled (I see an event in the event log & no exceptions).

    As a test, I have a small windows forms app with a button which tries to get the remote object. Here is the code from the Click event and the GetCurrentStatus method:

    private void button1_Click(object sender, System.EventArgs e)
    {
    PingChecker.cConnectionStateChanges x = new PingChecker.cConnectionStateChanges();
    x = GetCurrentStatus();

    foreach(PingChecker.ConnectionStateChange item in x)
    {
    System.Diagnostics.Trace.WriteLine(“item.Timestamp=” + item.Timestamp.ToUniversalTime());
    }

    System.Diagnostics.Trace.WriteLine(“Count is: ” + x.Count);
    }
    public PingChecker.cConnectionStateChanges GetCurrentStatus()
    {
    try
    {
    // Call GetObject to Activate our Remotable object
    PingChecker.ConnectionStateRemotable cscr = (PingChecker.ConnectionStateRemotable) Activator.GetObject(
    typeof(PingChecker.ConnectionStateRemotable), “tcp://wired:8001/cConnectionStateChanges”);

    // Return the inner class that contains the monitoring info
    return cscr.ConnectionStateStatus ;
    }
    catch(System.Exception ex)
    {
    System.Diagnostics.Trace.WriteLine(ex);
    System.Diagnostics.Trace.WriteLine(ex.InnerException);
    return null;
    }
    }

    The problem I am seeing is after the call to Activator.GetObject an error in the cscr object stating “Cannot evaluate field of a proxy object”. The GetCurrentStatus method returns without an exception, but it comes back empty-handed – no PingChecker.cConnectionStateChanges object.

    TIA for your help on this.

    Charlie

  • Charlie

    Hi,

    Im trying to implement your code & have a question:

    -Your code references a methos ‘GateStatus’
    “tcp://[SERVER]:8001/GateStatus”

    Where is this method implemented?

    From my client code (Windows Form app), Im getting an exception of type “Requested Service not found” whn I try to return the object from the GetCurrentStatus() method.

  • Brendan Tompkins

    The principle should be the same, see part 3.

  • Yi

    What about the case for using Web Service to control Windows Service? I need to start or stop a windows service by sending a SOAP request to the web service on the same machine, haven’t figure out how to do it.

  • Albert

    Thank you for this article very helpful Brendan, i really need the third part.

  • George

    This is a useful tutorial ! Thank you and please write the Part 3 we really need it !

  • Carlos

    Please continue with third part. Thanks

  • Philip_C

    This is a great tutorial ! Thank you and please write the Part 3 i really need it !

    :D

  • Guilherme

    Dear,

    I’m new in .NET and i have to do a Windows Service that will monitoring two things:

    1)If a website is online.

    2)If a Data Base is ok, and the time of response os this Data Base.

    Can you help me ??

    Thanksss..

    Guilherme

    guimendonca@veloxmail.com.br