This is the changelog for the 2.x series.

• Fix a bug where Traversable queues (non-array iterables) will fail because the reset(), current(), and next() array functions are incompatible
• Improve the overall code quality of the project (through internal changes that do not alter the public API)

• Raise a more obvious error message when Relay is given an empty queue (#43)
• Fix a bug that broke callable middleware (#45)
• Properly declare PSR dependencies and make it clear that Relay provides an implementation of PSR-15's Psr\Http\Server\RequestHandlerInterface (#46)
• Add support for queue items that implement Psr\Http\Server\RequestHandlerInterface (#48)
• Replace abandoned zendframework/zend-diactoros with same version laminas/laminas-diactoros

The 2.x series introduces a major change to the way Relay handles middleware. While the 1.x series featured a "double pass" signature (function (request, response, next)), the 2.x series is fully-compatible with PSR-15's "single pass" or "lambda" recommendation (function (request, handler) : response).

Note that middleware designed for Relay 1.x are not compatible with PSR-15 server request handlers ("dispatchers") like Relay 2.x.