wrapping .TLB to .DLL for .NET

[normanordas]

I have a .tlb file(neteng.tlb) that works on a vb 6 program. This library has module-based methods that i can call anywhere and it works fine. Next I wrapped this module-based DLL(neteng.tlb) to another VB 6 COM as you have said. I did that by adding a referenced first to "neteng.tlb" library then adding the following code to the class (NETENGAPI is a module inside "neteng.tlb"): '------------------------------------ Option Explicit Public Function NE_IsNetwork1(name As String) As Boolean NE_IsNetwork1 = NETENGAPI.NE_IsNetwork(name) End Function Public Function NE_OpenNetwork1(name As String, mode As AccessModeEnum) As Long NE_OpenNetwork1 = NETENGAPI.NE_OpenNetwork(name, mode) End Function Public Sub NE_InitNetworkEngine1() Call NETENGAPI.NE_InitNetworkEngine End Sub Public Sub NE_ExitNetworkEngine1() Call NETENGAPI.NE_ExitNetworkEngine End Sub '------------------------------------ Then save the file as Netengs.DLL (class name is NetEngEng) ===>>> Process Flow: neteng.tlb wrapped inside ->netengs.dll Note: Netengs.dll purpose was to call those module-based methods inside neteng.tlb thru the class NetEngEng so we can expose them when we migrate it to .NET assembly code. I created another VB6 Prog to test netengs.dll if its gonna work (i add a referenced first to netengs.dll). See code below:. Option Explicit Dim shp As String Dim net As NetEngs.NetEngEng Private Sub Form_Load() Set net = New NetEngEng Call net.NE_InitNetworkEngine1 shp = "d:\tracking\shapes\roadcenter_mkt_only.nws" 'Dim net As New NetEngs.NetEngEng Dim bool As Boolean 'bool = net.NE_IsNetwork1(shp) bool = net.NE_IsNetwork1(shp) If bool Then MsgBox ("Is network") Else MsgBox ("Is not network") End If Dim ne As Long ne = net.NE_OpenNetwork1(shp, 1) If (ne = 0) Then MsgBox "Network " + shp + " not found.", vbCritical Exit Sub End If Call net.NE_ExitNetworkEngine1 End Sub '----------- but when i run the prog and it step into the code Call net.NE_InitNetworkEngine1 it raises this error: The instruction at "0x00001de2" referenced at "0x00001de2". The memory could not be "read." My neteng.dll that wraps neteng.tlb don't even work inside another vb 6 prog. Whats wrong with neteng.dll here? Am i missing something? It would be more disaster if i import this to interop assembly. Tnx!

[Heath Stewart]

You have a method trying to access the address of itself, where it won't find any data obviously.

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[normanordas]

This is content my my type-library when i open it thru OLE Viewer: // typelib filename: neteng.tlb [ uuid(281078B0-B4B9-11D2-92C7-0000F878079B), version(1.2), helpstring("Library Neteng"), helpfile("NetEngine.HLP"), helpcontext(00000000) ] library NETENG { // TLib : // Forward declare all types defined in this typelib typedef enum { NE_READWRITE = 0, NE_READONLY = 1 } AccessModeEnum; typedef enum { NE_SIMPLE = 0, NE_FASTINDEX = 1 } IndexTypeEnum; [ dllname("neteng.dll") ] module NETENGAPI { [entry(0x60000000), helpstring("Initialize the network engine."), helpcontext(0x0000756f)] void _stdcall NE_InitNetworkEngine(); [entry(0x60000001), helpstring("Exit from the network engine."), helpcontext(0x00007570)] void _stdcall NE_ExitNetworkEngine(); [entry(0x60000002), helpstring("Takes in the public attribute record for the Network and creates a Network. This results in a directory whose name is part of the Network attribute record. The Network remains until deleted. A NULL pointer is returned if the Network could not be created."), helpcontext(0x00007573)] ------------------------------------------------------------- as you can see my neteng.tlb file has a module NETENGAPI but what i don't understand is the inclusion of [dllname("neteng.dll")]. Does it mean that the functionality of the NETENGAPI module resides in another file and that is neteng.dll? Indeed there's another fle associated with it but i can't open it by OLE Viewer it says its not a valid type lib. How i can i use NETENGAPI then in my VB.Net app?Adding reference to neteng.tlb only shows the enumeration members but the module methods can't be called nor recognized(NETENG.NETENGAPI.NE_InitNetworkEngine() is not a member the editor says). Tnx a lot!

[Heath Stewart]

They aren't methods - they're functions. You need to P/Invoke these from the neteng.dll like so:

[DllImport("neteng.dll")]
private static extern void NE_InitNetworkEngine();
 
[DllImport("neteng.dll")]
private static extern void NE_ExitNetworkEngine();

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