Why is the REST API for On-Premises Mailboxes Being Discontinued?
Microsoft recently announced that they are discontinuing the REST API for On-Premises Mailboxes. This announcement has caused some confusion and uncertainty in the community, so let’s take a few moments to break down why this is happening and what it means for Exchange administrators.
What is the REST API?
REST stands for Representational State Transfer and is an architectural style for distributed hypermedia systems such as the web. In the context of Exchange, the REST API is used to provide access to Exchange data such as mailboxes, calendar items, contacts, etc. from applications and web services.
Why is the REST API Being Discontinued?
Microsoft is discontinuing the REST API for On-Premises Mailboxes for a few reasons. The first is that the REST API was developed for Exchange Online, which has a different architecture than an on-premises Exchange server. As such, the REST API is not optimized for on-premises use and can lead to performance issues and scalability issues.
The second reason is that Microsoft recommends using the Exchange Web Services (EWS) API instead as it is more optimized for on-premises use and provides more features. Microsoft also recommends using the EWS API for applications that require access to Exchange data from on-premises servers.
Finally, Microsoft has decided to focus their development efforts on the EWS API, which is more in line with their current cloud-first strategy.
What Does this Mean for Exchange Administrators?
For Exchange administrators, the discontinuation of the REST API means that any applications or web services that were using the API will need to be updated to use the EWS API instead. Microsoft has provided a set of instructions on how to do this, which can be found here.
In addition, Exchange administrators should keep in mind that the EWS API is more feature-rich than the REST API and can provide more options for applications and web services.
Conclusion
The discontinuation of the REST API for On-Premises Mailboxes is part of Microsoft’s ongoing effort to optimize its products and services for the cloud. Exchange administrators should take note of this announcement and update any applications or services that are using the REST API to use the EWS API instead.
References:
The End of the REST API for On-Premises Mailboxes Preview
