Limit concurrent users

DCrake · Apr 23, 2008

I have a VB app connected to a Access database, it has multi user access across a LAN. My question is is it possible to count the number of people currently using the app. I want to have many users but only allow 5 bums on seats at any one time.

Any Ideas.

namliam · Apr 23, 2008

Will if you "log in and out" of the database with connections... it should be easy...

Just create a table where you log usernames that are currently logged in... It is a simple matter of doing a select count(*) from table to fetch the number of current users.
Offcourse temporarily you would have 6 or even more to check if they are allowed in... but.... they are atleast not touching your " real " data.

Alternatively you could make a seperate database where your FE app logs in and out, where you count... thus keeping your data/BE free of this "extra" connections

DCrake · Apr 23, 2008

Simple Software Solutions

I had that in mind when I was writing the thread, However I thought about using to lock file to test it. But as I already have a user table I might as well use that. Thanks anyway.

namliam · Apr 23, 2008

The lock file in the "newer" versions (IIRC 2002 and newer) are scrambled/unreadable as far as I know

It used to be (access 2) that you could retrieve your users from it... but no more (I think).
A seperate user table, in particular if you allready have one is a sure fire way of getting "things done"

Good luck

Darth Vodka · Apr 23, 2008

a log in, log out thing is all well, but the users will muck it up when they control-alt-delete

you can write a function to check how many people are in the db:-

Code:

Function CountUsers(cn As ADODB.Connection)
    Dim rs          As ADODB.Recordset


    ' The user roster is exposed as a provider-specific schema rowset
    ' in the Jet 4.0 OLE DB provider.  You have to use a GUID to
    ' reference the schema, as provider-specific schemas are not
    ' listed in ADO's type library for schema rowsets

    Set rs = cn.OpenSchema(adSchemaProviderSpecific, _
    , "{947bb102-5d43-11d1-bdbf-00c04fb92675}")

    CountUsers = 0
    With rs
        Do Until .EOF
            CountUsers = CountUsers + 1
            .MoveNext
        Loop
    End With
     
    rs.Close
    Set rs = Nothing


End Function

Sub test()
    Dim cn As ADODB.Connection
    Set cn = New ADODB.Connection
    ' Open the connection
    With cn
      .Open "Provider=Microsoft.Jet.OLEDB.4.0;" & _
         "Data Source=\\opssvr01\tpg_bo_data\EMTN\EMTN back end.mdb"
    End With
    
    MsgBox CountUsers(cn)
    
    Set cn = Nothing
   
End Sub

then when they log in, test for it and boot them out if the limit is exceeded

Darth Vodka · Apr 23, 2008

the LDB tells you who has logged in during the time it was created...you can open it in notepad, but it's not that useful in a multi user environment

hmm i'm not too sure that the currentproject connections aren't just read off the ldb anyway...

DCrake · Apr 23, 2008

Simple Software Solutions

Thanks Darth added the snippet to my splash screen and it worked. Just one thing you have to deduct 1 from the record count as you become a connection as well.

Darth Vodka · Apr 23, 2008

DCrake said:
Thanks Darth added the snippet to my splash screen and it worked. Just one thing you have to deduct 1 from the record count as you become a connection as well.

depends if you're in it

Limit concurrent users

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