Article application applicability confusion and conflation of COM and VSTO

[brreich]

The article here: https://learn.microsoft.com/en-us/office/dev/add-ins/develop/make-office-add-in-compatible-with-existing-com-add-in is confusing in a number of ways.

Firstly, it says that the Web Add-In manifest way of defining the Equivalent Add-Ins applies to Word, Excel, PPT, and Outlook. However, immediately following this it has a section detailing how to define these equivalences for Outlook only using GPO. It is unclear whether Outlook can use EITHER method, or whether it can only use the registry policy method. If it is only GPO, then it should be removed from the list of apps for which the Web add-in manifest mechanism applies. If both, this should be explicitly called out, and it should also be clarified what happens if both the GPO and web add-in manifest information is provided for the same web add-in.

Also, this article frequently conflates VSTO and COM add-ins, which are not the same thing. For example, it repeatedly says that the "ProgId" should be used to map the native add-in to the equivalent web add-in. However, VSTO add-ins do not have "ProgID"s, since this is strictly a COM concept. VSTO add-ins have a name in the registry at the same place where COM add-ins have ProgIDs, but the way you tell the difference is whether the VSTO name key has a "Manifest" value under it which holds a path to the managed assembly that defines the entry point to the add-in for the VSTO loader to call. There is no ProgID or COM class look-up or anything like that. It is unclear whether what is really meant is that the "name" of the add-in, as defined for the key under the "AddIns" key of the registry, is what is really intended. If that really is the intent, then that wording should be used to avoid confusion. It is true that for COM add-ins this is ALSO the ProgID, but for VSTO the use of this term is unclear and confusing since it doesn't apply.

It is also unclear whether the W/X/P web add-in manifest approach to this equivalent add-in feature also supports VSTO via the name, since that documentation of the manifest schema element also seems to suggest ONLY COM (and XLL) and ONLY ProgId is supported (see "EquivalentAddIn XML Manifest Element"). But it seems from THIS article that maybe the VSTO add-in name also works? And if so, again, this is confusing and the web add-in manifest schema documentation is then inaccurate and should be updated.

[AlexJerabek]

Thanks for reporting this @brreich.

@davidchesnut, could you please investigate?

[davidchesnut]

Thanks @brreich, I'm checking into VSTO support for this feature. I'll add this to our backlog to get the article updated correctly. Thanks!

[brreich]

Thanks. I checked with one of the folks who is familiar with the Outlook side of things, and he said that Outlook supports both the registry and manifest mechanisms for defining equivalent add-ins, so it's correct Outlook is listed in both sections, but I think it could be made clearer that Outlook supports both, and what happens when equivalent add-in definitions exist in both places.

Appreciate the follow-up regarding the VSTO question.

Bryan

From: David Chesnut @.> Sent: Friday, May 10, 2024 3:25 PM To: OfficeDev/office-js-docs-pr @.> Cc: Mention @.>; Author @.> Subject: Re: [OfficeDev/office-js-docs-pr] Article application applicability confusion and conflation of COM and VSTO (Issue #4558)

Thanks @brreichhttps://github.com/brreich, I'm checking into VSTO support for this feature. I'll add this to our backlog to get the article updated correctly. Thanks!

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