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Yii2 PSR-7 Bridge

A PSR-7 bridge and PSR-15 adapter for Yii2 web applications.

The usecase for this bridge is to enable Yii2 to be utilized with PSR-7 and PSR-15 middlewars and task runners such as RoadRunner and PHP-PM, with minimal code changes to your application (eg requiring no changes to any calls to Yii::$app->request and Yii::$app->response within your application).

Note that this is currently very alpha quality. It "works" in that a PSR7 request is accepted as input and it returns a valid PSR7 response that is mostly in line with what you would expect.

However, features and functionality are missing. Many things don't work, others have unexpected side-effects. You are advised not to use this package at this time.

See the Current Status checklist at the bottom of the README file for what is current implemented and what we could use help with.

What to help out?

Contributors are welcome! Check out the Current Status checklist for things that still need to be implemented, help add tests, or add new features!

Installation

This package can be installed via Composer:

Tests

Tests can be run with phpunit.

Usage

Due to the nature of this package, several changes are needed to your application.

Dispatcher

1. Modify your request and response components within your web application config to be instance of yii\Psr7\web\Request and yii\Psr7\web\Response, respectively:

If you're using a custom Request class, simply have it overload yii\Psr7\web\Request to inherit the base functionality.

2. Set the following environment variables to your task runner. With RoadRunner, your configuration might look as follows:

All environment variables must be defined.

3. Run your application with a PSR-15 compatible dispatcher.

For example, to Go/Roadrunner, you can use the component as follows:

Worker Crash Protection

With each request PHP's memory usage will gradually increase. This is unavoidable due to Yii2 not being designed normal PHP call stacks (Nginx + PHP-FPM, Apache2 CGI, etc...), rather than request-request tools such as a RoadRunner. Calling $application->clean() will tell you if the current script usage is within 10% of your memory_limit ini set. While most workers will handle a out-of-memory crash exception, you can use this method to explicitly tell the current worker to stop and be reconstructed to avoid HTTP 500's thrown by out-of-memory issues. This will also resolve any unexpected memory leaks that occur due to framework memory reservation.

Session

This library is fully compatible with yii\web\Session and classes that descend from it with a few caveats.

1. The application component adds the following session ini settings at runtime. Do not overwrite these settings as they are necessary for yii\web\Session.

2. Don't access $application->getSession() within your worker.

Request

yii\Psr7\web\Request defines a stand-in replacement for yii\web\Request. To access the raw PSR-7 object, call Yii::$app->request->getPsr7Request().

Response

yii\Psr7\web\Response directly extends yii\web\Response. All functionality is implemented by yii\Psr7\web\traits\Psr7ResponseTrait, which you can use as a trait within any custom response classes. Alternatively you can directly extend yii\Psr7\web\Response.

ErrorHandler

yii\Psr7\web\ErrorHandler implements custom error handling that is compatible with yii\web\ErrorHandler. yii\Psr7\web\Application automatically utilizes this error handler. If you have a custom error handler have it extend yii\Psr7\web\ErrorHandler.

Normal functionality via errorAction is supported. Yii2's standard error and exception pages should work out of the box.

PSR-7 and PSR-15 compatability

\yii\Psr7\web\Application extends \yii\web\Application and implements PSR-15's \Psr\Http\Server\RequestHandlerInterface providing full PSR-15 compatability.

PSR-7

If your application doesn't require PSR-15 middlewares, you can simply return a PSR-7 response from the application as follows:

No dispatcher is necessary in this configuration.

PSR-15 with middlewares/utils package

Since \yii\Psr7\web\Application is PSR-15 middleware compatible, you can also use it with any PSR-15 dispatcher.

This library does not implement it's own dispatcher, allowing the developer the freedom to use a PSR-15 compatible dispatcher of their choice for middleware handling.

As an example with middlewares/utils:

PSR-15 Middleware Filters

This package also provides the capabilities to process PSR-15 compatible middlewares on a per route basis via yii\base\ActionFilter extension.

Middlewares run on a per route basis via these methods aren't 100% PSR-15 compliant as they are executed in their own sandbox independent of the middlewares declared in any dispatcher. These middlewares operately solely within the context of the action filter itself. Middlewares such as middlewares/request-time will only meaure the time it takes to run the action filter rather the entire request. If you need these middlewares to function at a higher level chain them in your primary dispatcher, or consider using a native Yii2 ActionFilter.

Authentication

If your application requires a PSR-15 authentication middleware not provided by an existing yii\filters\auth\AuthInterface class, you can use yii\Psr7\filters\auth\MiddlewareAuth to process your PSR-15 authentication middleware.

\yii\Psr7\filters\auth\MiddlewareAuth will run the authentication middleware. If a response is returned by your middleware it will send that response. Otherwise, it will look for the attribute specified by your authentication middleware, and run yii\web\User::loginByAccessToken() with the value stored in that attribute.

Note your yii\web\User and IdentityInterface should be configured to handle the request attribute you provide it. As most authentication middlewares export a attribute with the user information, this should be used to interface back to Yii2's IdentityInterface.

A simple example with middlewares/http-authentication is shown as follows using the username attribute populated by Middlewares\BasicAuthentication.

Note: This class should be compatible with yii\filters\auth\CompositeAuth as it returns null. Note however that the yii\web\Response object will be populated should an HTTP status code or message be returned. If you require custom responses you should extend this class or manually trigger handleFailure().

Other Middlewares

yii\Psr7\filters\MiddlewareActionFilter can be used to process other PSR-15 compatible Middlewares. Each middleware listed will be executed sequentially, and the effective response of that middleware will be returned.

As an example: middlewares/client-ip and middlewares/uuid is used to return the response time of the request and a UUID.

The middleware handle also supports PSR-15 compatible closures.

Middlewares are processed sequentially either until a response is returned (such as an HTTP redirect) or all middlewares have been processed.

If a response is returned by any middleware executed, the before action filter will return false, and the resulting response will be sent to the client.

Any request attribute or header added by any previous middleware will be include in the response.

Why does this package exist?

Performance

The performance benefits of task runners such as RoadRunner and PHP-PM are extremely difficult to ignore.

While PHP has had incrimental speed improvements from 7.0 (phpng), the performance of web based PHP applications is limited by the need to rebootstrap every single file with each HTTP request. While Nginx + PHP-FPM is fast, even with opcache every file has to read back into memory on each HTTP request.

PSR-7 servers enable us to keep almost all of our classes and code in memory between requests, which mostly eliminates the biggest performance bottleneck.

Be sure to check out the Performance Comparisons wiki page for more information on the actual performance impact on the yii2-app-basic app.

It is expected that PHP 7.4 preloading would improve performance further.

PSR-7 and PSR-15 Compatability

While not strictly the goal of this project, it's becomming more and more difficult to ignore PSR-7 and PSR-15 middlewares. As the Yii2 team has punted PSR-7 compatability to Yii 2.1 or Yii 3, existing Yii2 projects cannot take advantage of a standardized request/response pattern or chained middlewares.

Developers conforming to PSR-7 and PSR-15 consequently need to re-implement custom middlewares for Yii2, which runs contrary to the fast, secure, effecient mantra of Yii2. This library helps to alleviate some of that pain.

How this works

This package provides three classes within the yii\Psr7\web namespace, Application, Request, and Response, and a Psr7ResponseTrait trait that can be used to add PSR7 response capabilities to your existing classes that extend yii\web\Response.

To handle inbound requests, the yii\Psr7\web\Application component acts as a stand in replacement for yii\web\Application for use in your task runner. It's constructor takes the standard Yii2 configuration array, and a additional ServerRequestInterface instance. The Application component then instantiates a yii\Psr7\web\Request object using the ServerRequestInterface provided.

Since yii\web\Application::bootstrap uses the request component, the request component needs to be properly constructed during the application constructor, as opposed to simply calling $app->handleRequest($psr7Request);

yii\Psr7\web\Request is a stand-in replacement for yii\web\Request. It's only purpose is to provide a interface between ServerRequestInterface and the standard yii\web\Request API.

Within your modules, controllers, actions, Yii::$app->request and Yii::$app->response may be used normally without any changes.

Before the application exists, it will call getPsr7Response on your response component. If you're using yii\web\Response, simply change your response component class in your application configuration to yii\Psr7\web\Response. If you're using a custom Response object, simply add the yii\Psr7\web\traits\Psr7ResponseTrait trait to your Response object that extends yii\web\Response to gain the necessary behaviors.

Limitations

• File streams currently don't work (eg yii\web\Response::sendFile, yii\web\Response::sendContentAsFile, yii\web\Response::sendStreamAsFile)
• The Yii2 debug toolbar yii2-debug will show the wrong request time and memory usage.
• Yii2 can't send SameSite cookies

Current Status

• [x] Implement custom `Application component.
• [x] Convert a PSR7 Request into yii\web\Request object.
• [x] Return a simple response.
• [x] Routing.
• [x] Handle yii\web\Response::$format.
• [x] Work with standard Yii2 formatters.
• [x] Handle HeaderCollection.
• [x] Handle CookieCollection.
• [x] Handle yii\web\Response::$stream and yii\web\Response::$content.
• [x] Implement yii\web\Response::redirect.
• [x] Implement yii\web\Response::refresh.
• [x] GET query parameters yii\web\Request::get().
• [x] POST parameters yii\web\Request::post().
• [x] yii\web\Request::getAuthCredentials().
• [x] yii\web\Request::loadCookies().
• [x] Per-action Middleware authentication handling.
• [x] Per-action middleware chains.
• [x] Reuse Application component instead of re-instantiating in each looåp.
• [x] yii\web\ErrorHandler implementation.
• [x] Run yii-app-basic.
• [x] Bootstrap with yii\log\Target.
• [x] session handling
• [x] yii-debug.
• [x] yii-gii.
• [x] Fix fatal memory leak under load
• [ ] yii\filters\auth\CompositeAuth compatability.
• [x] Implement comparable sendFile, sendStreamAsFile
• [ ] yii\web\Request::$methodParam support. (Not really applicable to ServerRequestInterface)
• [ ] Test Coverage

This project is licensed under the BSD-3-Clause license. See LICENSE for more details.