It is just announced that SharePoint will start supporting WebHooks and I got to know the news through the PnP WebCast. I through of just summing up a few advantages for the implementations that align with the WebHooks over the other mechanisms available. At first glimpse it looked like a replacement to the remote event receivers, but both have their own advantages. As the full details of the implementation is yet to come, my assumptions are based on what is announced so far.
First of all, WebHooks is a callback mechanism that supports notifying the changes rather than waiting clients to query it every time. Once subscribe with an expiration time defined or not, it will keep sending the update notifications until it is acknowledged through the endpoint. It is said SharePoint will support subscriptions with expiration date up to 6 months since its initial subscription.
Its HTTP based, can be supported within many endpoints
SharePoint is not the first product that supports WebHooks. It is a callback mechanism that is supported by many platforms that consume HTTP protocols. Therefore, integration of SharePoint data changes through WebHooks will look mostly similar to the other technologies. This means no special training and not many concerns when it comes to implementation.
Multiple Subscriptions for a single endpoint
As of what is said, it will support changes within the SharePoint lists initially. You can create multiple WebHooks to a single endpoint. This gives the ability to have multiple services that consume these changes through different endpoints.
For example, you can have one endpoint that triggers an action when a set of fields changed and another endpoint that handles a different process when a set of fields changed.
It's set to expire
This can be an advantage as well as disadvantage at a different time. You can define the subscription to invalidate within a specific time where as maximum is 6 months. On or before the 6 months, you can renew the subscription/ make another subscription to the same endpoint.
Perhaps this might be rated higher. The beauty of the WebHooks is that SharePoint waits till it is acknowledged. Once a change alert is sent to and endpoint that is subscribed, SharePoint expect an acknowledgement through an HTTP OK status within 5 seconds. Though it is not defined a limit yet, it is said that SharePoint will keep sending the change alert until the acknowledgement comes in.
This will ensure that the changes are received and acknowledged by the subscriber.
Many implementation opportunities
It's a light weight message that comes in when a change occurred. Subscriber can get the changes using a simple CSOM call. This is not platform specific and new in terms of implementations. Therefore the possible implementation scenarios are very high and excellent in terms of the potentials.
So the news are still hot and cant wait till the Summer 2016 (for US) to tryout some code. Until then stay tuned to Office Dev PnP.
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