Hi Charles Law,
You could use a Singleton for this:
Imports System
Imports System.IO
Imports System.Collections
Imports System.Runtime.Serialization.Formatters.Binary
Imports System.Runtime.Serialization
' There should be only one instance of this type per AppDomain.
<Serializable()> Public NotInheritable Class Singleton
Implements ISerializable
' This is the one instance of this type.
Private Shared ReadOnly theOneObject As New Singleton
' Here are the instance fields.
Public someString As String
Public someNumber As Int32
' Private constructor allowing this type to construct the Singleton.
Private Sub New()
' Do whatever is necessary to initialize the Singleton.
someString = "This is a string field"
someNumber = 123
End Sub
' A method returning a reference to the Singleton.
Public Shared Function GetSingleton() As Singleton
Return theOneObject
End Function
' A method called when serializing a Singleton.
Private Sub GetObjectData(ByVal info As SerializationInfo, _
ByVal context As StreamingContext) _
Implements ISerializable.GetObjectData
' Instead of serializing this object, we will
' serialize a SingletonSerializationHelp instead.
info.SetType(GetType(SingletonSerializationHelper) )
' No other values need to be added.
End Sub
' Note: ISerializable's special constructor is not necessary
' because it is never called.
End Class
<Serializable()> Friend NotInheritable Class SingletonSerializationHelper
Implements IObjectReference
' This object has no fields (although it could).
' GetRealObject is called after this object is deserialized.
Public Function GetRealObject(ByVal context As StreamingContext) As
Object Implements IObjectReference.GetRealObject
' When deserialiing this object, return a reference to
' the Singleton object instead.
Return Singleton.GetSingleton()
End Function
End Class
Class App
<STAThread()> Shared Sub Main()
Dim fs As New FileStream("DataFile.dat", FileMode.Create)
Try
' Construct a BinaryFormatter and use it
' to serialize the data to the stream.
Dim formatter As New BinaryFormatter
' Create an array with multiple elements refering to
' the one Singleton object.
Dim a1() As Singleton = {Singleton.GetSingleton(),
Singleton.GetSingleton()}
' This displays "True".
Console.WriteLine("Do both array elements refer to the same object?
" & _
Object.ReferenceEquals(a1(0), a1(1)))
' Serialize the array elements.
formatter.Serialize(fs, a1)
' Deserialize the array elements.
fs.Position = 0
Dim a2() As Singleton = DirectCast(formatter.Deserialize(fs),
Singleton())
' This displays "True".
Console.WriteLine("Do both array elements refer to the same object?
" & _
Object.ReferenceEquals(a2(0), a2(1)))
' This displays "True".
Console.WriteLine("Do all array elements refer to the same object?
" & _
Object.ReferenceEquals(a1(0), a2(0)))
Catch e As SerializationException
Console.WriteLine("Failed to serialize. Reason: " & e.Message)
Throw
Finally
fs.Close()
End Try
End Sub
End Class
"Charles Law" <bl***@nowhere.com> wrote in message
news:ec**************@TK2MSFTNGP15.phx.gbl...
I have just been asked how to share functions and properties between two
running applications. For example, I have App1 and App2 both running on
the same machine. App1 uses a DLL (perhaps) that contains function SetProp().
When App1 calls it, a property in the DLL is set to "abc". App2 calls a
function GetProp(), in the same DLL. GetProp() should return "abc".
This sounds like a simple thing to do, but making the DLL variable shared
and making both applications load the same DLL does not work. On
reflection, I can see why that wouldn't (shouldn't) work, but how can it be done;
preferably without having to jump through security hoops.
TIA
Charles
