How to develop/deploy a web app for Microsoft Excel 2013 and later without a network share or SharePoint?

Question

I'm attempting to follow this deceptively simple tutorial on MSDN for making an Excel 2013 web app:

http://msdn.microsoft.com/library/office/fp142255%28v=office.15%29

I'm stuck on the "To specify a trusted location for the manifest" and "To test and run the Hello World app" steps. I don't have a network share nor a SharePoint server available. I don't know why I can't simply just point to the manifest file itself somewhere and load the target application directly (and ideally not have to restart Excel after each little change to see if it works). I'm not sure what the actual problem is since the only output I see is a vague "Cannot connect to catalog" message when I go to find and insert the app into Excel. The Trust Center dialog in Excel actively refuses local drive references (e.g. C:\path\to\app) with a message about needing "https://". Excel did accept "\\.\[driveletter]\path\to\app\" as a valid "network share" (a bug?) but it still displays the "Cannot connect to catalog" message in the insert dialog. I've also tried variants on the theme such as excluding the trailing backslash '\' from the path and specifying the full path and filename of the app and various combinations of app directory and filenames.

I also attempted to throw the test app up on both a local and remote web server and then pointed Excel at the manifest (as well as the app's directory), but the web server logs indicate that Excel is attempting to connect to a SharePoint REST API endpoint (/pathtoapp[/appname.xml]/_api/web/lists?$filter=TemplateFeatureId%20eq%20guid'61e874cd-3ac3-4531-8628-28c3acb78279'&$select=Id"), which results in a 404 (i.e. not a SharePoint server) and then Excel displays the unhelpful "Cannot connect to catalog" message. The server logs at least proved that Excel was actually doing something and the Trust Center did at least warn me it was going to treat the URL as a SharePoint URL. However, there's no obvious way to tell Excel to load an individual app from a plain-ol' web server instead of SharePoint nor what the web server's reply should be if I don't have nor desire nor the capability (e.g. a Linux server) to install SharePoint.

So what am I missing or doing wrong? Making an Excel web app on a local computer is something sensible the developer of the web app might want to do. Letting users install the web app via a direct URL is also something sensible that a developer might want to do.

Answer 1

Finally figured it out:

\\.\[drive_letter]:\path\to\app\

Is allowed and works fine. The directory has to contain one or more XML files. And don't forget the colon after the drive letter.