{title:'Client Versioning', updated:'9.0.0'}

Client version headers are used to support backwards compatibility for breaking REST interface changes. Using them, you're able to return different responses based on which client is making a request.

The APIs involved with defining client version headers are:

- {@link oajr.annotation.Rest}
  - {@link oajr.annotation.Rest#clientVersionHeader() clientVersionHeader}
- {@link oajr.annotation.RestOp}
  - {@link oajr.annotation.RestOp#clientVersion() clientVersion}
- {@link oajr.RestContext.Builder}
  - {@link oajr.RestContext.Builder#clientVersionHeader(String) clientVersionHeader(String)}

##### Example:

| // Option #1 - Defined via annotation resolving to a config file setting with default value. | @Rest(clientVersionHeader="Client-Version") | public class MyResource { | | // Call this method if Client-Version is at least 2.0. | // Note that this also matches 2.0.1. | @RestGet(path="/foobar", clientVersion="2.0") | public Object method1() { | ... | } | | // Call this method if Client-Version is at least 1.1, but less than 2.0. | @RestGet(path="/foobar", clientVersion="[1.1,2.0)") | public Object method2() { | ... | } | | // Call this method if Client-Version is less than 1.1. | @RestGet(path="/foobar", clientVersion="[0,1.1)") | public Object method3() { | ... | }