This document provides the following tips and tricks for using EntireX DCOM Wrapper:
See also Using DCOM Wrapper Objects with Web Scripting Languages.
The parameter definition in the IDL file must match exactly the parameter data area of the Natural subprogram with respect to format, length, dimensions, direction, number and order of parameters.
Because the number of required GUIDs may change if the parameter definition in the IDL file changes with respect to groups, you must deregister the old object and delete the g<library>.h file before (re-)generating the object.
From EntireX 5.3.1.10 on, methods for better array support are available for arrays defined in groups.
set property <object name>.<access to group>.<array name>_indexAccess(<index list>) = value get property <variable> = <object name>.<access to group>.<array name>_indexAccess(<index list>)
When the ActiveX application calls a DCOM Wrapper method, the parameters must match exactly:
the number of parameters
the parameter type (string, int etc.)
how these parameters are passed to the called method:
IN parameters should be passed by value;
OUT and INOUT
parameters should be passed by reference.
If in doubt, look at the type library of the generated Wrapper object. Use the Microsoft C++ tool OLE/COM Object Viewer (oleview.exe) to inspect the type library, or look at the generated IDL file in the generated object directory.
If the dll generated by EntireX DCOM Wrapper is imported by a client application, the compiler can exit with error "error C2011:'IServiceProvider' : 'struct' type redefinition". If this happens, add the following to the #import clause:
rename("IServiceProvider","IServiceProviderX")
Example:
#import "<path>\DCOMWrapperObject.dll" no_namespace rename("IServiceProvider","IServiceProviderX")
If the dll generated by EntireX DCOM Wrapper is imported by a client application and this application is an ATL application, it may be necessary to import the dll type library with the following statement:
#include <dispex.h>
#import "DCOMWrapperObject.tlb" no_namespace exclude("IDispatchEx")
exclude("IServiceProvider") rename ("IDispatch","IDispatchEx")
If syntax errors occur in the IDL file, the most likely cause is the use of reserved words as parameters. Not only the keywords of IDL (library, program, etc.) are reserved, but also all valid format-length combinations. For example, you cannot use "A1" as the name of a parameter.
If syntax errors occur during compilation of the generated C++ sources, a likely cause is the use of reserved C++ words as parameter names in the IDL file, or a library that contains a program with the same name.
If you generate an ActiveX automation server a second time, the existing GUIDs will be reused. To prevent this, delete the header file g<library>.h in the generated object directory.
Parameter names used in the IDL file conflict with the Visual C++ MIDL compiler, so avoid keywords used in the MIDL definition. The DCOM Wrapper uses the MIDL compiler from EntireX Version 6.1.1.8 on (only Windows platforms). The changes were necessary because of the internal change from the IDispatch to the IDispatchEx interface to support scripting languages correctly.
On the client side, language-dependent restrictions may occur independent of the functionality offered by the DCOM Wrapper object.
While using the Wrapper-generated objects, the .NET application throws an error message queryinterface <interface name> failed. To prevent this, uncheck ASP scripting support in the Setting DCOM Wrapper Properties.
If the Extended Interface was used, the client application has to make
sure that the Wrapper-generated object was called from an STA thread.
In an ASP.NET application, the client application can use the
aspcompat attribute on your ASP.NET page or if
the application, such as web service, does not provide an attribute such as
aspcompat, use an STA thread in your
application.
Include the attribute aspcompat into the
file WebForm.aspx.
<%@ Page aspcompat=true Language="vb".........
' Create new thread class
Public Class STAThreadClass
Dim Obj As EXXDCOMTypeLibrary.ProgClass
Dim sUser As String
Public Sub Run()
' Set thread state to STA
System.Threading.Thread.CurrentThread.ApartmentState = Threading.ApartmentState.STA
Obj = New EXXDCOMTypeLibrary.ProgClass()
Try
Obj.ServerAddress = "localhost@RPC/SRV1/CALLNAT"
Obj.TEST(sUser)
' catch an error, if one thrown
Catch ex As Exception
ReturnValues.ErrorText = "Error: " + ex.ToString
End Try
Obj = Nothing
End Sub
End Class
' main web service function
<WebMethod()> Public Function DoCall()
Dim STA As New STAThreadClass()
' create the thread
Dim InstanceCaller As New Thread(New ThreadStart(AddressOf STA.Run))
' start the thread and wait for execution
InstanceCaller.Start() 'start thread
InstanceCaller.Join() 'wait for called STA thread
End Function
When using N, NU, P or PU data types, the only valid decimal character is the decimal point.
Examples:
1234.34 OK 1234,34 not allowed 123,400.00 not allowed
Only the decimal point "." is allowed!