asked on

DCOM and WithEvents

Hi,

Imaging the scenario where a hotel has 5 reception desks. Each reception desk has a computer which displays the room availability. However, when one of the receptionists makes a booking, I want the other screens to update immediately (or as near as).

I've looked into DCOM and WithEvents etc.. but can't work out how to fit it all together.

I've created an ActiveX exe, containing the following code...

'------- Class: clsTestEv ---------
Option Explicit
Public Event Updated(Fred$)

Public Sub DoIt()
RaiseEvent Updated("Do it")
End Sub

Public Sub EndIt()
RaiseEvent Updated("End it")
End Sub
'----------------------------------

The class name would be 'testev.ClsTestEv'

I then created project 2, which is hopefully going to create a reference to the clsTestEv class, call the 'DoIt' procedure, and then receive an event...

what am I doing wrong ???

here's my code..

'-------Form : Form1---------
Private WithEvents blob As clsTestEV
Option Explicit

Private Sub Form_Load()
Dim x As Object
Set x = CreateObject("testev.clstestev")
x.DoIt
Set x = Nothing
End Sub

Private Sub blob_Updated(Fred As String)
MsgBox Fred
End Sub
'----------------------------------

The object gets created, but when I call 'doit', the messagebox does not pop up. Surely it should ???

Once this is working, and I'm fairly confident I'll get this bit working ok, how do I declare the 'WithEvents' when the object I'm creating is on a remote machine ??, I can create the object ok using the createobjects("testev.clstestev","machinname"), but how do I tell WithEvents what the object is ???

Marine

Hi can you try this? I created recently an app where i raise my own events ant it worked for me. Here is the code i used maybe it can work out for you.Good Luck

in Class.
--Class Code----
Public Event Change(sSql as string,lst as ListView)
Public Function SelCategory(Book As String, lstBooks As ListView)
Dim sSql As String
On Error GoTo err_book
Call Con 'opens connection
RaiseEvent Change(Book, lstBooks)
cnAcct.Close
Exit Function
err_book:
msgbox err.description
End Function

---Form Code---
Private WithEvents objBook As IBooks
Private Sub objBook_Change(sSql As String, lst As MSComctlLib.ListView)
Dim rs As New ADODB.Recordset, lstItem As ListItem, i As Integer
On Error GoTo err_Rec
rs.Open sSql, cnAcct, adOpenStatic, adLockPessimistic
If rs.RecordCount < 1 Then
MsgBox "NO RECORDS HAVE BEEN FOUND ON THIS TOPIC" & Chr(13) & Chr(10) & _
" PLEASE SELECT ANOTHER TOPIC", vbInformation, "Search Found 0 Records"
Exit Sub
End If
rs.MoveFirst
Do While Not rs.EOF
Set lstItem = lst.ListItems. _
Add(, , CStr(rs!Author))
For i = 1 To lst.ColumnHeaders.Count - 1
lstItem.SubItems(i) = IIf(Not IsNull(rs(i)), rs(i), "")
Next
rs.MoveNext
Loop
rs.Close
Exit Sub
err_Rec:
MsgBox "ERROR OCCURED WHILE RETRIEVING RECORDS"
Err.Clear
End Sub

smegghead

ASKER

Hmm, I can't see anything different in your code except that you seem to be running it within one project ?? I want to compile the ActiveX exe and use it remotely & locally.

Joebob

The reason that your code is not working is because you declare a variable blob to recieve events, but you never assign it to anything. You instead create another variable x that creates the object and calls the doit method. If you are going to use x to call the doit method then x needs to be declared withevents. Another way that might work is to set blob equal to x before calling the doit method.

Joebob

Didn't see the rest of your question.

You asked:
Once this is working, and I'm fairly confident I'll get this bit working ok, how do I declare the 'WithEvents' when the object I'm creating is on a remote machine ??, I can create the object ok using the createobjects("testev.clstestev","machinname"), but how do I tell WithEvents what the object is ???

My Answer:
You can't use late binding. You must declare your variable as the correct projectname.classname datatype. The CreateObject function doesn't require that the variable it is returning the value to is of type object, it just requires that it is either a <font color="red">generic object</font> OR the <font color="red">correct object</font>.

smegghead

ASKER

Thanks JoeBob

So, if I can't use late binding, how do I declare the object when it resides on another machine, do I have to register a local copy ?? surely not...

Is there another program that allows me to set up a reference to an object on a remote machine ??

PS. Does this approach sound like the most appropriate for what I am trying to achieve ??

PPS. I'm leaving work now, so I may go quiet for a few hrs.. (til I get home - sad eh ??)

ASKER CERTIFIED SOLUTION

Joebob

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smegghead

ASKER

I've now done this using Tcp/Ip, it works very well.

smegghead

ASKER

Comment accepted as answer

smegghead

ASKER

Hi

Thanks for your help joebob / marine.. I've done it a different way now, using TCPIP, but I'm sure your answers were correct.

Rich.

PS. I awarded the points to joebob, 'cos he mentioned using TCPIP, sorry marine !!