Get published Office 365 calendar JSON without OAuth2 step? - rest

Question

Edit:
Initially, the question was how to get an Office365 calendar in JSON without authentication; but, what I meant was how to get an Office365 calendar in JSON without requiring the OAuth2 step (so, for example on the server-side other authentication methods are acceptable to retrieve the calendar data).
Problem:
I would like to use the Office 365 REST API to access this published calendar (i.e. the "read" operation only since the calendar is published), so that I can "style" the calendar the way I prefer. So, I am looking for a public API approach to using one of my calendars. The code examples for the Office 365 REST API that I found use OAuth to authenticate the client. This seems like overkill.
I have come up with some possible solutions, so any suggestions on the best approach is welcome.
Background:
I have a published calendar in Office365, which gives me a feed:
http://outlook.office365.com/owa/calendar/USER#DOMAIN/CALENDAR_NAME/calendar.ics
and the URL:
http://outlook.office365.com/owa/calendar/USER#DOMAIN/CALENDAR_NAME/calendar.html
How can I do what "calendar.html" is doing, so that I can display a calendar the way I would like it to be displayed (instead of IFraming what Office365 provides)?
Example:
Here is an example URL using the REST API:
https://outlook.office365.com/api/v1.0/users/USER#DOMAIN/calendars
The browser will bring up a basic authentication dialog, so it looks like OAuth is not the only method required (one possible solution, the request could be proxied from a local server that is calling the REST API using basic authentication).
Issues:
One issue might be that the calendar "publishing" feature is meant for a limited amount of data (e.g. 1 year prior or in the future at the most) which is what I assume is what the iCalendar (*.ics) file would contain for any request.
Using the REST API with authentication assumes that there isn't a date range restriction (since one can query the calendar using the REST API, I assume you could query further back than a year).
Possible solutions:
Proxy the request from another server by making the REST API calls using basic authentication. Caching might also be needed since it appears the response times could be slow. The calendar could be either JavaScript that consumes a local endpoint, or HTML content generated at the server.
It looks like the Office365 AuthenticationContext.AcquireTokenAsync() will accept a ClientCredential (client id and secret) or also a UserCredential (simple username and password). So, I think I can run a local proxy service that uses the Office365 library by manually passing in credentials to the function that acquires a token. (I still need to test this to make sure that the function will indeed work this way.)
Simply iFrame the "calendar.html" page provide by Office 365. (Cross domain is prevented, unless it's on one of the Microsoft hosted solutions "Something Webs".)
If using the iCalendar (*.ics) feed, then one would need a transformation function for the iCalendar format to JSON (https://github.com/kewisch/ical.js), then JavaScript or a calendar library could be used to design a custom calendar. (This wouldn't be very convenient for viewing a year's worth of calendar events without cashing and providing a querying mechanism, except for displaying one month back and forward. So, some sort of ics2json to use on FullCalendar might work for only a couple months of calendar history.)
Any suggestions on the best approach (or another approach not listed here) is welcome.

Answer 1

The Office 365 APIs require Oauth2 in order to function. If you are using Visual Studio to develop your app, the O365 tools for Visual Studio + OWIN middleware will handle a lot of the oauth work for you.
If oauth is absolutely not an option, I'd consider using the EWS APIs instead, which can use basic authentication (more info on that here on MSDN).