What Protocols are Supported By Outlook for 2-way Calendar Sync?

Question

I'd like to create a calendar that Outlook can subscribe to which can be updated either in Outlook or on the "calendar service" (Whatever that ends up being).

What protocols does Outlook support for stuff like this, and are those protocols two-way like I described?

e.g. I want Outlook to be able to update an existing calendar item that came from the subscribed calendar.

Answer 1

I recently did my own research on this and found the following website which I believe outlines the majority of the options.

Office 365 Supports:

• ActiveSync
• EWS
• MAPI
• WebDav

And as @camelsWriteInCamelCase indicates:

• The Outlook REST API

Answer 2

According to this article:

You must have an email provider that uses Micosoft Exchange ActiveSync. Most common providers like Gmail do.

From Wikipedia:

Exchange ActiveSync (commonly known as EAS) is a proprietary protocol designed for the synchronization of email, contacts, calendar, tasks, and notes from a messaging server to a smartphone or other mobile devices. The protocol also provides mobile device management and policy controls. The protocol is based on XML. The mobile device communicates over HTTP or HTTPS.

If you want to make your own synchronization you can use Outlook REST API. Or you can use any of the existing applications, for example:

• Outlook Google Calendar Sync
• Outlook CalDav Synchronizer