Versioning Policy

OpenNMS HORIZON provides strict backwards compatibility guarantees for all supported APIs (excluding alpha APIs, which may be changed without notice, and beta APIs, which may occasionally be changed in a non-backwards compatible manner). OpenNMS HORIZON will continue to support older clients against newer servers. For example, a 3.1 client will work against 3.0, 3.1, and 3.2 servers.

Changes of APIs for non-security related reasons will involve, at minimum, two minor releases (3.1 to 3.2 to 3.3, for example) to allow older clients to update. Using new capabilities may require newer clients. A 3.2 server may have additional capabilities that a 3.1 client cannot use and a 3.2 client may have additional capabilities that are not supported by a 3.1 server.

Table 1. Compatibility Matrix

X.Y (Client)

X.Y+N [1] (Client)

X.Y (Server)



X.Y+N [1] (Server)



1 Fully compatible.
2 Client may not be able to access server features.
3 Client may provide options and features that may not be compatible with the accessed server.

1. Where N is a number greater than 1.