# API Versioning

The Sway Charts REST API attempts to maintain backward compatibility with the clients provided the following:

* Clients ignore the data they do not understand
* Clients only use the data they need

For example, in case of XML representation, clients must make sure they do not couple their logic with current XML representation in such a way that adding new fields causes their application to malfunction. This allows adding new data to resources without breaking clients.

If any data is removed or data meaning is changed, a new notification API version is introduced. Switch between different versions is based on the URI of the API (e.g. <http://host/api/v1> for version 1 and <http://host/api/v2> for version 2).

*API versioning* supports only *major* integer versions such as 1,2,3 etc. With the API, there is no notion of minor releases.

| Change                                                       | New Version Released?                                                                                                          |
| ------------------------------------------------------------ | ------------------------------------------------------------------------------------------------------------------------------ |
| Addition of a new data field to data representation          |                                                                                                                                |
| Changing the logical meaning of a field                      | <img src="https://github.githubassets.com/images/icons/emoji/unicode/2714.png?v8.png" alt="heavy_check_mark" data-size="line"> |
| Removing a field                                             | <img src="https://github.githubassets.com/images/icons/emoji/unicode/2714.png?v8.png" alt="heavy_check_mark" data-size="line"> |
| Changing the default representation, currency units etc.     | <img src="https://github.githubassets.com/images/icons/emoji/unicode/2714.png?v8.png" alt="heavy_check_mark" data-size="line"> |
| Addition of new independent requests                         |                                                                                                                                |
| New business rules and/or application flow                   | <img src="https://github.githubassets.com/images/icons/emoji/unicode/2714.png?v8.png" alt="heavy_check_mark" data-size="line"> |
| New default values for optional request parameters or fields | <img src="https://github.githubassets.com/images/icons/emoji/unicode/2714.png?v8.png" alt="heavy_check_mark" data-size="line"> |