If you have a choice, use the latest released version of the client library, available from the 60East website (www.crankuptheamps.com).
Feature compatibility is designated with the major and minor version number. Starting with the 3.8 release, we have coordinated version numbers between clients and servers to indicate feature support. For example, clients with version numbers that start with 3.8 support the features in AMPS 3.8 and previous versions.
Features that change the protocol between client and server are only introduced when the major or minor version number of the server is updated. Maintenance releases and hotfix releases of the server do not update the protocol.
Released versions of a client are fully tested with the current preview version and the latest hotfix of the versions under support at the time the client was released. More recent versions have the latest features and bugfixes. Server and clients with matching major and minor version numbers (such as 3.9, 4.0, 4.3) are always tested together for release.
60East tests clients with previous versions of the AMPS server to help ensure backward compatibility. In some cases (for example, when features are added that extend the protocols used to communicate between client and server), previous version clients may run into problems when communicating with later versions of the AMPS server.
Previous versions of clients are not guaranteed to work with features introduced in later versions. For example, a 4.3 version client may not be able to process messages from a 5.2 version server when 5.2 version features are used (although the 4.3 client should work properly so long as only features present in 4.3 are used).
When updating to a new major/minor version (for example, upgrade an AMPS server from 3.9 to 4.3 or upgrading from 4.3 to 5.0), 60East recommends updating client applications first, then updating the server that those applications communicate with.
Keywords: client compatibility, upgrade client, version number compatibility