relayphp.com

What It Is

Relay is a PSR-15 server request handler in the PHP ecosystem—in other words, a dispatcher for executing a middleware queue. Its role is clearly defined: it takes a queue of middleware entries, calls handle() on a server request, executes the queue in first-in-first-out order, and ultimately returns a PSR response.

Core Capabilities

Based on the documentation, Relay supports standard PSR-15 middleware as well as callable middleware that matches a specified signature, and the two can be mixed in the same queue. You can create an instance directly with new Relay($queue), or use RelayBuilder to build one. A particularly useful feature is the queue entry resolver: when entries in the queue are not already-instantiated objects, but instead class names or similar items, you can provide a resolver callable to turn them into instances. This makes it possible to integrate Relay with custom factory mechanisms or dependency injection containers.

Language, Framework, and Ecosystem

Relay is designed for PHP and can be installed via Composer: composer require relay/relay ~2.0. The documentation states that it can be used with any PHP framework or container, making it more of a low-level standards-based component than a complete solution tied to a specific framework. In terms of ecosystem, the page points users to middlewares/psr15-middlewares for middleware that can work with Relay.

Pricing and Deployment

The documentation does not provide any commercial pricing, paid plans, or payment information. Relay is essentially a library installed into a PHP project, not a hosted SaaS product, so it can run on your own servers or within your application environment. The open-source license, maintainer, and commercial support options are not described in the text and would need to be checked separately in the package repository or on Packagist.

Pros and Cons

Its strengths are that it follows standards, has a small and clear concept, and is well suited to projects that need a PSR-15 middleware pipeline. The resolver mechanism improves flexibility when integrating with containers or factories, and support for callable middleware also helps with compatibility with legacy code. The downside is that the documentation is fairly basic, mainly covering installation and examples, with little information on exception handling, performance, version compatibility, or production best practices. Service support, licensing, and maintenance activity are also not covered.

Who It’s For and Access from China

Relay is suitable for PHP backend developers, framework authors, and teams that need to build a standardized request-processing chain. The documentation does not provide enough information to judge accessibility from China. If users mainly obtain it through Composer/Packagist, the actual experience will depend on network conditions and mirror configuration. Alternatives include middleware mechanisms built into PHP frameworks, or other dispatchers compatible with PSR-15.