Unified Communications Web APIs are available since more than two years now, and earlier this year they've been (finally) enabled on O365 as well.

Still, as of today, there's no official SDK provided from MS to interact with UCWA.
There are concepts in UCWA that are quite unique or not obvious at all: such as working with the Event Channel; for which there are no good working examples, or sufficient documentation.

More often we hear during presentations speakers saying: "... but because we're not animal, there's a package/library for that!"

I still consider myself an animal, but I would like anyway to have proper documentation and an SDK to work with; while building my solutions targeting Skype for Business. In the same way I can do today already while targeting SharePoint or many other 365 services, for example.

When a user changes a bound cell, it triggers an Office.EventType.BindingDataChanged event and a callback associated with it. In the Excel Online browser-based client and not the desktop Excel client, if the callback function makes further changes to the bound cell e.g. changing its color based on input value (*), this produces uncaught errors after ctx.sync is called.

These errors surface outside my functions after they return control to the browser (chrome in this case), so I am ignoring them at the moment and hope they have no ill effects but thought you'd like to know.

I originally mitigated this by removing and re-adding the change event listeners, but this is way too slow due to the calls back and forth to Microsoft, so the new mitigation has been to add the binding id to a list whenever programmatic changes are made to a cell and have the callback query the list (using eventArgs.binding.id) to decide whether or not to eat the event. It's not ideal but it's a lot faster than the asynchronous calls to office.js.

(*) Also, if the user begins to enter a value into an empty bound cell then deletes it using backspace and presses enter, this causes the error even if the callback function doesn't change the contents of the cell (!?)

Excel Online and Office.js provide an excellent way of integrating Microsoft's tools with other cloud-based services, but latency is currently a barrier and this is a way of solving it.

I have developed an office.js task pane app that binds to many cells, each linked to variables in mathematical models running on an external server. When the user enters a value, that value is sent to a remote server, results are computed, and they are sent back to be written to various other cells in the spreadsheet.

However, a value entered by the user is not directly passed to the callback function for a bound cell, so there is a delay of usually a few hundred ms but sometimes a few seconds while Excel Online running within the browser contacts Microsoft to sync the entered value and then Microsoft sends it back via ctx.sync or myBinding.getDataAsync.

Without this unnecessary round trip, user-entered values can be passed directly into the callback function, sent to my mathematical model servers, processed, sent back and written to the cells. And all this can be done inside 100 ms and then sync to Microsoft it its leisure.

I have a SharePoint site set up for alpha testers with an example spreadsheet and the task pane app, so if you'd like to play with it and see what I mean, just let me know and I'll add you to the site.

While it is possible to add custom links to the suite bar by using the admin site, it would be useful to either provide a way to programmatically add/remove links for a user, or provide an admin tool to provide default pinned apps on the suite bar.

For example, in an education tenant, we may want to provide a link to pin MS Classroom and a link to a SharePoint site for every student by default.

Users should continue to be able to modify their apps, but we should have the ability to set default values.

If there were client-side APIs available, one could write simple script calls to Add links to the user's default app bar.