COM Forwarding

COM that Vertec Cloud App, as of Vertec 6.7.0.7 COM Forwarding is available, with which extension COM objects of the external system can be accessed.  

For example, COM Forwarding objects can be used in the server Python Code side Python code, whose actions are then forwarded to the Cloud App where they are applied to the actual COM objects of the third-party program.

Extensions that were operated via COM with earlier Vertec versions could only be On-Premises with the Vertec Desktop App and therefore only On-Premises. These interface extensions should be migrated to COM Forwarding in view of the discontinuation of the Vertec Desktop App with Vertec 7.1. See the article Switch COM to COM Proxy and COM Forwarding.

Module "vtccom"

The functionality for COM forwarding is included in the Vertec Python module vtccom, which is also available as a Stub File.

The feature vtccom.createobject(<progid>) returns a COM object that can be used in Python.

import vtccom

word = vtccom.createobject("Word.Application")
word.Visible = True

doc = word.Documents.Add()
doc.SaveAs(r"C:\temp\Test Document.docx")

To ensure that the extensions with COM Forwarding also work with Restricted Scripting, only Whitelist modules may be used modules in the script.

Depending on the implementation of the third-party product used (COM Server), COM Forwarding may cause incompatibilities. In these cases, an alternative solution must be specifically sought.  

Security

To prevent a COM Forwarding script on the server from “unnoticed” executing code in the Cloud App, the client user is asked for permission once when a COM server on the client is called, and this permission is saved on the client for future calls.

When accessing a COM server via COM Forwarding (calling vtccom.createobject()) a dialog appears in the Cloud App that a server script tries to access this object on the client.

• If access is granted, the script is executed and the permission is saved on the client. The query will not appear on future calls to the same COM server.
• If access is not allowed, execution will be aborted without a message. The message will appear again on repeated access.

The Accounting Interfaces with COM Forwarding supplied by Vertec are already stored. Therefore, this query does not arrive at the first call.

The authorized COM servers are saved in the registry key HKEY_CURRENT_USER\SOFTWARE\Vertec\ComObjectWhitelist.