Using middleware to cross languages
Except in cases where you are trying to communicate between different versions of PHP, PSR-7 middleware will be of minimal use. Recall what the acronym stands for: PHP Standards Recommendations. Accordingly, if you need to make a request to an application written in another language, treat it as you would any other web service HTTP request.
How to do it...
In the case of PHP 4, you actually have a chance in that there is limited support for object-oriented programming. Accordingly, the best approach would be to downgrade the basic PSR-7 classes described in the first three recipes. There is not enough space to cover all the changes, but we present a potential PHP 4 version of
Application\MiddleWare\ServerRequest. The first thing to note is that there are no namespaces! Accordingly, we use a classname with underscores, _, in place of namespace separators:class Application_MiddleWare_ServerRequest extends Application_MiddleWare_Request implements Psr_Http_Message_ServerRequestInterface...
