For security reasons the Central/AlarmService web service were removed from XProtect in the 2019 R2 release. The web service has been marked obsolete for a long time and was only kept for the reason of backward compatibility, but it was now decided to remove it due to security concerns.
Unfortunately, this was not communicated to our partners and thus it might have resulted in some integrations being broken. Whether this is the case can be seen from the requests to the XProtect server returning an error similar to this (wireshark tracing might be needed to observe it):
The HTTP service located at http://<server-address:22331/Central/AlarmService is unavailable.
Due to the lack of communication we have released a hotfix reintroducing the web service. However, only use it if you experience a broken integration resulting in the above mentioned error and please let the integrating partner know that they need to upgrade their integration in accordance with the below instructions, as the web service will not be reintroduced in any future releases.
The hotfix as well as further instructions on how to veriy whether this is the issue you are experiencing can be found in this knowledge base article.
This will not affect any integrations using the newer (and secure) web services Central/AlarmService2 and Central/AlarmServiceToken, and existing integrations using Central/AlarmService should reimplement their integration using these web services instead. Refer to the Alarm List protocol sample in the MIP SDK for inspiration on how to do that.