In a new post to his site Matthew Weier O’Phinney, lead developer on Zend Framework and representative in the PHP-FIG, covers the acceptance of PSR-15 by the group. PSR-15 relates to the creation of server request handlers and middleware that can use PSR-7 formatted messages.
This new standard defines interfaces for request handlers and middleware. These have enormous potential impact on the PHP ecosystem, as they provide standard mechanisms for writing HTTP-facing, server-side applications. Essentially, they pave the way for developers to create re-usable web components that will work in any application that works with PSR-15 middleware or request handlers!
He starts with a bit of background around the initial idea of the standard and some of the discussions that came up around it. The initial draft of the standard was modified to more correctly handle issues around response modification and the use of "handlers" for request/response manipulation. He then covers the final version of the standard, defined in the standard’s documentation and enforceable via the psr/server-handler interface. Finally he covers how to use this to create re-usable middleware and an example using Expressive.