Re: Singleton Objects

Tech-Archive recommends: Speed Up your PC by fixing your registry

From: pSm (pSm_at_discussions.microsoft.com)
Date: 11/01/04 

Date: Mon, 1 Nov 2004 13:19:01 -0800

Ken,
   Here's the server 'Type' -->
--------------------------------------------------------------------------------------------
Imports System.Diagnostics
Public Class clsRemoteType
    Inherits MarshalByRefObject

    Private arrIDs(10) As String
    Private Shared lastid As String

    Private Shared message As String
    Private count As Integer = 0
    Public evt As New System.Diagnostics.EventLog("RemoteLog.txt")

    Public Sub clsRemoteType()

        evt.WriteEntry("APP", "Remote Type Created")
    End Sub

    Protected Overrides Sub finalize()
        evt.WriteEntry("APP", "Remote Type Destroyed" + CStr(DateTime.Now))
    End Sub

    Public Sub send(ByVal id As String, ByVal msg As String)
        Dim i As Integer
        Dim blnFound As Boolean
        For i = 0 To count
            If (arrIDs(i) = id) Then
                'Found - Already present no need to add
                blnFound = True
                Exit For
            End If
        Next

        If (Not blnFound) Then
            arrIDs(count) = id
            count = count + 1
        End If
        lastid = id
        message = msg

        evt.WriteEntry("APP", "Message written -" + message +
CStr(DateTime.Now))
    End Sub

    Public Function receive() As String
        Return (lastid + " : " + message)
    End Function
End Class
--------------------------------------------------------------------------------------------
The Host -->

Imports System
Imports System.Runtime.Remoting
Module Module1

    Sub Main()
        Try
            RemotingConfiguration.Configure("../RemotingHost.exe.config")
            Console.Write("Waiting for Connections to arrive --")
            
            Console.ReadLine()
       
        Catch ex As Exception
            Console.Write("Exception Occured..")
        End Try
    End Sub

End Module

-------------------------------------------------------------------------------------------

The Server 'Config'

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
        <system.runtime.remoting>
                <application>
                        <service>
                                <wellknown
                                mode="Singleton"
                                type="clsRemoteType, RemoteType.clsRemoteType"
                                objectUri="RemoteTypeURI.rem"
                                />
                        </service>
                        <channels>
                                <channel ref="http" port="8989"/>
                        </channels>
                </application>
        </system.runtime.remoting>
</configuration>

----------------------------------------------------------------------------------------------
The client -->

Code when a message is sent :

Private Sub btnSend_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles btnSend.Click
        Dim obj As New RemoteType.clsRemoteType
        obj.send("ABC", txtMsg.Text)
End Sub

Code that polls ( a timer is used)

Private Sub tmPollMsg_Tick(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles tmPollMsg.Tick
        Dim obj As New RemoteType.clsRemoteType
        Dim str As String
        str = obj.receive()
        If Trim(str) <> ":" And lastmessage <> str Then
            lblMsg.Text = lblMsg.Text + str + vbCrLf
            lastmessage = str
        End If
    End Sub
------------------------------------------------------------------------------------------
Client Config -->
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
   <system.runtime.remoting>
      <application>
         <client>
            <wellknown
               type="clsRemoteType, RemoteType.clsRemoteType"
               url="http://FLL020361:8989/RemoteTypeURI.rem"
            />
         </client>
      </application>
   </system.runtime.remoting>
</configuration>

---------------------------***************-------------------------------------

Thanks

"Ken Kolda" wrote:

> If the class is exposed as a singleton, the Message value should be shared
> across all clients. The fact that you're seeing the object destroyed after
> each call from a client implies this is SingleCall instead of Singleton
> (although even then I wouldn't expect the finalizer to run right away unless
> your forcing garbage collection). You want to post some code if you still
> have issues.
>
> Ken
>
>
> "pSm" <pSm@discussions.microsoft.com> wrote in message
> news:B31F2E03-2A5C-4E32-B9EC-FC7EB29E84D4@microsoft.com...
> > Hi Sam,
> > Thanks for the post , but I am not really looking on how to
> implement
> > the chat program, but understanding/clearing my remoting concepts.
> >
> > To re-iterate, I would like to know if my understanding that if the object
> > is singleton, and the message property is shared, every user would have
> > access to the same message value, is correct or not ?
> >
> > Thanks,
> >
> >
> > "Sam Santiago" wrote:
> >
> > > Here's a remoting Chat example that uses events to accomplish what you
> want.
> > > Also, if you are seeing the finalizer run each time you might have
> defined a
> > > SingleCall SAO vs. a Singleton SAO. Check out this example for more
> info:
> > >
> > > http://support.microsoft.com/default.aspx?scid=kb;en-us;312114
> > >
> > > Thanks,
> > >
> > > Sam
> > >
> > > --
> > > _______________________________
> > > Sam Santiago
> > > ssantiago@n0spam-SoftiTechture.com
> > > http://www.SoftiTechture.com
> > > _______________________________
> > > "pSm" <pSm@discussions.microsoft.com> wrote in message
> > > news:1DD1BB89-DC6E-422A-A8E7-C0BB2F05A273@microsoft.com...
> > > > Hi,
> > > > I was trying to write a basic chat client/server. I used remoting for
> > > this.
> > > > The server type uses a shared property message to keep track of the
> last
> > > sent
> > > > message. All the clients poll the server every 10ms to see if a new
> > > message
> > > > is arrived.
> > > >
> > > > The server type is singleton. My guess was since the object is
> singleton
> > > and
> > > > message is shared, the last mesage posted by anyone would be visible
> to
> > > > anybody else.
> > > >
> > > > For example, say A says 'Hi' . When B polls for the message, he should
> see
> > > > the 'Hi'. But what I see is, every client is seeing only the message
> that
> > > he
> > > > has posted and nothing else. So, if A says 'Hi' and B says 'Bye', A
> only
> > > sees
> > > > 'Hi' and B only sees 'Bye'. Can anyone help me understand what's wrong
> ?
> > > >
> > > > Second question is, after I saw that this was happening, I tried
> finding
> > > out
> > > > if the object is getting destroyed. So I put in a finalizer and some
> logs
> > > in
> > > > it. I see the finalizer run after every call from the client.Why is
> this
> > > so ?
> > >
> > >
> > >
>
>
>

Relevant Pages

  • More readable
    ... Imports System.Runtime.Remoting ... Private history As Queue = New Queue ... Private debugWriter As IO.StreamWriter 'For debug purpose, ... Public Sub New ...
    (microsoft.public.dotnet.framework.remoting)
  • Re: Collection disappearing at run time
    ... the Tab so that it doesn't take any arguments. ... > Private _tabHeight As New Unit ... > Public Overrides Property HeightAs Unit ... > Protected Overrides Sub OnInit ...
    (microsoft.public.dotnet.framework.aspnet.buildingcontrols)
  • MAPI Emails from Access
    ... I realize this code is quite long, but could someone take a look at the sub ... Private Const mcERR_DOH = vbObjectError + 10000 ... Private mstStatus As String ... Dim db As Database, rs As Recordset ...
    (microsoft.public.access.formscoding)
  • Re: CType and annoying build errors
    ... Imports System.Data.SqlClient ... Private SkipTabControl1IndexChangedFunctionality As Boolean = True ... Private Sub TabControl1_SelectedIndexChanged(ByVal sender As ... Private WithEvents cmSel As New SqlCommand ...
    (microsoft.public.dotnet.general)
  • Re: DC another Problem
    ... > Private PointsDraw As ClassPoints ... > Private Sub Command1_Click ... > Dim p As Classpoint ... > Public Property Let X ...
    (microsoft.public.vb.winapi.graphics)