Newsgroup: it.discussioni.varie
Titolo: Mex con segnalazione di errore

Mi è arrivata una e-mail dall'India senza contenuto e mi è uscito il
seguente messaggio:
"Un controllo ActiveX nella pagina non è sicuro. Di conseguenza, la pagina
potrebbe non essere visualizzata in modo corretto".
Qualcuno mi può dare cortesemente una spiegazione?
Grazie
Angelo



da profano ho cercato ACTIVEX su un motore di ricerca, ho trovato:
http://msdn.microsoft.com/default.asp
da cui:
http://support.microsoft.com/support/kb/articles/Q282/1/68.asp
cioe':
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INFO: Hosting ActiveX Controls in a Netscape Plug-in
  The information in this article applies to:
      Microsoft Internet Explorer (Programming) versions 4.x, 5.x
  SUMMARY
  In order to reuse ActiveX controls, which are developed for use in
Internet Explorer, in
  other browsers that do not support them, you may want to create a
Netscape plug-in that
  hosts the ActiveX control. This article describes general guidelines
on how to host ActiveX
  controls in a Netscape plug-in and is divided into the following
sections: 
      Framework Overview 
      Design Guidelines 
      Potential Problems 
  MORE INFORMATION
  Framework Overview
  It is helpful to review the two component frameworks, ActiveX
controls and Netscape
  plug-ins, to note their similarities and differences and evaluate
what is needed to create a
  functional design. 
  Netscape Plug-ins
  Netscape plug-ins were among the first component frameworks to be
used in Web
  development. On the Microsoft Windows platform, plug-ins are
constructed as standard
  Win32 dynamic-link libraries (DLLs) that rely on a series of
predefined entry points to
  expose functionality. They are given a window handle (HWND) by their
container, which
  they then subclass to receive user interaction and operating system
notifications through
  Windows messages. 
  ActiveX Controls
  ActiveX controls are lightweight, reusable Component Object Model
(COM) components.
  They are given a site (in the form of a COM interface pointer) by
their container, and they
  use COM methods and interfaces to communicate with the container.
ActiveX controls are
  smaller, simplified versions of object linking and embedding (OLE)
controls (as defined by
  the OLE Controls 96 specification). ActiveX controls do not
necessarily have an HWND;
  they can be windowless, in which case their container forwards them
the information that
  is normally conveyed through Windows messages. 
  Design Guidelines
  Basically, a Netscape plug-in that hosts ActiveX controls must
provide a way to translate
  the information and requests that are relayed as Windows messages
into COM method
  calls.
  The single most important (and difficult) task for the plug-in
developer is to implement all
  of the COM interfaces that are required for an ActiveX control
container. The following
  interfaces are implemented in a standard ActiveX control container: 
      IOleInPlaceFrame 
      IOleInPlaceUIWindow 
      IOleInPlaceSite 
      IOleClientSite 
      IAdviseSink 
      IOleControlSite 
      IDispatch 
      IPropertyNotifySink 
  If the plug-in is designed to host only one ActiveX control whose
behavior you control, you
  may omit (or only partially implement) some of these interfaces.
However, if the plug-in is
  designed to be a general purpose control container, it is critical
that you implement these
  interfaces fully and correctly to allow maximum interoperability
between the plug-in and
  the ActiveX controls that it hosts.
  After you implement all of the required COM interfaces, the plug-in
instantiates the control
  as any other container does: it initializes the COM Library through
the OleInitialize
  function and creates an instance of the control (through
CoCreateInstance,
  CoGetClassObject, and so on). When the plug-in ends, it also
destroys the control
  instance and uninitializes the COM Library. 
  Potential Problems
  Because this is such a complex design, you may encounter several
problems: 
      Internet Explorer provides a rich set of COM interfaces, the
IHTML* interfaces, to programmatically
      manipulate the Document Object Model (DOM) of the current HTML
page. Many ActiveX controls take
      advantage of this functionality to interact with the page on
which they are hosted. Other browsers may
      not provide this functionality; as a result, the control may
generate errors.
      Similarly, Internet Explorer exposes the IWebBrowser2 COM
interface through which ActiveX controls can
      interact with it programmatically. This interface may not be
present on other browsers; as a result, the
      control cannot access this functionality.
      Internet Explorer allows script code on an HTML page to
communicate with an ActiveX control on the page.
      To do this, Internet Explorer translates script calls that are
made to the <OBJECT> tag that hosts the
      control into IDispatch calls (such as GetIDsOfNames and Invoke)
that are delegated to the control.
      Although other browsers may use the plug-in as an intermediary
to achieve a similar functionality, the
      browser must somehow notify the plug-in of a script call. This
functionality is obviously not guaranteed.
  REFERENCES
  For more information on the OLE Controls 96 Specification, see the
following Microsoft Web
  site: 
http://support.microsoft.com/support/ie_dev/Ole%20Controls%2096.doc
  For more information on the Netscape Plug-in API Reference, see the
following Netscape
  Web site: 
http://developer.netscape.com:80/docs/manuals/communicator/plugin/refov.htm
  For more information on developing Web-based solutions for Internet
Explorer, please see
  the following Web sites:
 
http://msdn.microsoft.com/workshop/default.asp
 
http://msdn.microsoft.com/ie/
 
http://support.microsoft.com/highlights/iep.asp?FR=0&SD=MSDN
  The third-party contact information included in this article is
provided to help you find the
  technical support you need. This contact information is subject to
change without notice.
  Microsoft in no way guarantees the accuracy of this third-party
contact information.
  Additional query words: plugin 
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