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HTTP & Middleware Rob Allen November 2018

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Slim: The C in MVC Rob Allen ~ @akrabat

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Slim Created by Josh Lockhart (phptherightway.com) • PSR-2 coding style • PSR-4 autoloading • PSR-7 Request and Response objects • PSR-11 container support • Middleware architecture (PSR-15 upcoming) Rob Allen ~ @akrabat

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HTTP messages Rob Allen ~ @akrabat

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HTTP messages Rob Allen ~ @akrabat

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Request GET / HTTP/1.1 Host: akrabat.com User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:63.0) Gecko/20100101 Firefox/63.0 Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8 Accept-Language: en-GB,en;q=0.5 Accept-Encoding: gzip, deflate, br Connection: keep-alive If-Modified-Since: Mon, 04 Nov 2018 16:21:02 GMT Cache-Control: max-age=0 Rob Allen ~ @akrabat

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Response HTTP/1.1 200 OK Server: nginx/1.7.6 Date: Mon, 04 Nov 2018 16:27:06 GMT Content-Type: text/html; charset=UTF-8 Content-Length: 16091 Connection: keep-alive Keep-Alive: timeout=65 Vary: Accept-Encoding, Cookie Cache-Control: max-age=3, must-revalidate Content-Encoding: gzip Last-Modified: Mon, 04 Apr 2016 16:21:02 GMT Strict-Transport-Security: max-age=15768000 Rob Allen ~ @akrabat

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How do we do this in PHP? Request: • $_SERVER, $_GET, $_POST, $_COOKIE, $_FILES • apache_request_headers() / getallheaders() • php://input Rob Allen ~ @akrabat

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How do we do this in PHP? Response: • header() • http_response_code() • header_list() / headers_sent() • echo (& ob_*() family) Rob Allen ~ @akrabat

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How do we do this in PHP? URI: scheme://username:password@hostname:port/path?arg=value#anchor • parse_url() • parse_str() • http_build_query() Rob Allen ~ @akrabat

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PSR 7: HTTP messaging • Provides for a uniform access to HTTP messages • A set of interfaces for requests and responses • Created by Framework Interoperability Group Rob Allen ~ @akrabat

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It's just a set of interfaces Rob Allen ~ @akrabat

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RequestInterface • Protocol version • HTTP method • URI • Headers • Body Rob Allen ~ @akrabat

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ServerRequestInterface In addition to RequestInterface: • Server parameters • Query string arguments • Deserialised body • Uploaded Files • Attributes Rob Allen ~ @akrabat

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Response • Protocol version • Status code (& reason phrase) • Headers • Body Rob Allen ~ @akrabat

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Two key things about PSR-7 Rob Allen ~ @akrabat

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Firstly: Messages and URIs are IMMUTABLE! Rob Allen ~ @akrabat

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Immutability Request, ServerRequest, Response & Uri are immutable $uri = new Uri('https://api.joind.in/v2.1/events'); $uri2 = $uri->withQuery('?filter=upcoming'); $uri3 = $uri->withQuery('?filter=cfp'); Rob Allen ~ @akrabat

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Immutability Request, ServerRequest, Response & Uri are immutable $uri = new Uri('https://api.joind.in/v2.1/events'); $uri2 = $uri->withQuery('?filter=upcoming'); $uri3 = $uri->withQuery('?filter=cfp'); public function withQuery($query) { $clone = clone $this; $clone->query = $this->filterQuery($query); return $clone; } Rob Allen ~ @akrabat

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Common mistake $response = new Response(); $response->withStatus(302); $response->withHeader('Location', 'http://example.com'); return $response; Rob Allen ~ @akrabat

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What you meant! $response = new Response(); $response = $response->withStatus(302); $response = $response->withHeader('Location', 'http://example.com'); // or $response = new Response(); $response = $response->withStatus(302) ->withHeader('Location', 'http://example.com'); Rob Allen ~ @akrabat

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Headers Reading from the message: $request->hasHeader('Accept'); // boolean $request->getHeader('Accept'); // array $request->getHeaderLine('Accept'); // string Updating the message: $response = $response->withHeader('Accept', 'application/xml'); $response = $response->withAddedHeader('Accept', 'text/xml'); $response = $response->withoutHeader('Location'); Rob Allen ~ @akrabat

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Secondly: Message bodies are STREAMS Rob Allen ~ @akrabat

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Streams Allows for very large message bodies in a memory efficient manner $largeFile = __DIR__ . '/brand_guidelines.ppt'; return (new Response()) ->withHeader('Content-Type', 'application/vnd.ms-powerpoint') ->withHeader('Content-Length', (string) filesize($largeFile)) ->withBody(new Stream($largeFile)); Rob Allen ~ @akrabat

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Handling strings For strings, use the php:://temp stream: $response = $response->withBody(new Stream('php://temp')); $response->getBody()->write('Hello world!'); Rob Allen ~ @akrabat

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Mutable! $body->write('Hello'); $body->write(' World!'); $response = (new Response()) ->withStatus(200, 'OK') ->withHeader('Content-Type', 'application/html') ->withBody($body); Mitigate: Use read-only streams for server requests and client responses Rob Allen ~ @akrabat

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ServerRequest Attributes Allow passing of data from one component to the next // component 1 function findCountry($request) { $country = $this->geoLocate($request); $request = $request->withAttribute('country', $country); return $request; } // In an action method function listAction($request, $response, $args) { $country = $request->getAttribute('country'); // do something now that we know the country } Rob Allen ~ @akrabat

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Middleware Turns a request in to a response Rob Allen ~ @akrabat

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Middleware Rob Allen ~ @akrabat

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This is not new • NodeJS: Connect • Python: WSGI • Ruby: Rack • PHP: StackPHP, Slim Rob Allen ~ @akrabat

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PSR-7 Signature (by convention) function ( ServerRequestInterface $request, ResponseInterface $response, callable $next ) : ResponseInterface; Rob Allen ~ @akrabat

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PSR-7 Signature (by convention) function ( ServerRequestInterface $request, ResponseInterface $response, callable $next ) : ResponseInterface; Rob Allen ~ @akrabat

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PSR-7 Signature (by convention) function ( ServerRequestInterface $request, ResponseInterface $response, callable $next ) : ResponseInterface; Rob Allen ~ @akrabat

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PSR-7 Signature (by convention) function ( ServerRequestInterface $request, ResponseInterface $response, callable $next ) : ResponseInterface; Rob Allen ~ @akrabat

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PSR-7 Signature (by convention) function ( ServerRequestInterface $request, ResponseInterface $response, callable $next ) : ResponseInterface; Rob Allen ~ @akrabat

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PSR-7 Middleware function (ServerRequestInterface $request, ResponseInterface $response, callable $next) : ResponseInterface { // do something before // call down the chain to the next middleware if ($next) { $response = $next($request, $response); } // do something with $response after return $response; } Rob Allen ~ @akrabat

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PSR-7 Middleware function (ServerRequestInterface $request, ResponseInterface $response, callable $next) : ResponseInterface { // do something before // call down the chain to the next middleware if ($next) { $response = $next($request, $response); } // do something with $response after return $response; } Rob Allen ~ @akrabat

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PSR-7 Middleware function (ServerRequestInterface $request, ResponseInterface $response, callable $next) : ResponseInterface { // do something before // call down the chain to the next middleware if ($next) { $response = $next($request, $response); } // do something with $response after return $response; } Rob Allen ~ @akrabat

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PSR-7 Middleware function (ServerRequestInterface $request, ResponseInterface $response, callable $next) : ResponseInterface { // do something before // call down the chain to the next middleware if ($next) { $response = $next($request, $response); } // do something with $response after return $response; } Rob Allen ~ @akrabat

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PSR-7 Middleware function (ServerRequestInterface $request, ResponseInterface $response, callable $next) : ResponseInterface { // do something before // call down the chain to the next middleware if ($next) { $response = $next($request, $response); } // do something with $response after return $response; } Rob Allen ~ @akrabat

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What can you do with Middleware? Session CORS CSRF Logging Firewall Debug bar Authentication Throttling Error handling HTTP cache Honeypot Validation CSP etc... Rob Allen ~ @akrabat

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Middleware dispatching $app = new Slim\App(); $app->add($mw1); $app->add(SomeMiddleware::class); $app->add('MoreMiddleware'); $app->add([$instance, 'methodName']); $app->add(function ($request, $response, $next) { return $next($request, $response); }); $response = $app->run(); Rob Allen ~ @akrabat

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Data transfer between middleware Attributes allow passing of data from one middleware to the next class IpAddress { public function __invoke($request, $response, $next) { $ipAddress = $this->determineClientIpAddress($request); $request = $request->withAttribute('ip_address', $ipAddress); return $response = $next($request, $response); } // full source: github.com/akrabat/ip-address-middleware } Rob Allen ~ @akrabat

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Data transfer between middleware Attributes allow passing of data from one middleware to the next class IpAddressMiddleware { public function __invoke($request, $response, $next) { $ipAddress = $this->determineClientIpAddress($request); $request = $request->withAttribute('ip_address', $ipAddress); return $response = $next($request, $response); } // full source: github.com/akrabat/ip-address-middleware } Rob Allen ~ @akrabat

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Data transfer between middleware Attributes allow passing of data from one middleware to the next class IpAddressMiddleware { public function __invoke($request, $response, $next) { $ipAddress = $this->determineClientIpAddress($request); $request = $request->withAttribute('ip_address', $ipAddress); return $response = $next($request, $response); } // full source: github.com/akrabat/ip-address-middleware } Rob Allen ~ @akrabat

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Data transfer between middleware Attributes allow passing of data from one middleware to the next class IpAddressMiddleware { public function __invoke($request, $response, $next) { $ipAddress = $this->determineClientIpAddress($request); $request = $request->withAttribute('ip_address', $ipAddress); return $response = $next($request, $response); } // full source: github.com/akrabat/ip-address-middleware } Rob Allen ~ @akrabat

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Data transfer between middleware Attributes allow passing of data from one middleware to the next class IpAddressMiddleware { public function __invoke($request, $response, $next) { $ipAddress = $this->determineClientIpAddress($request); $request = $request->withAttribute('ip_address', $ipAddress); return $response = $next($request, $response); } // full source: github.com/akrabat/ip-address-middleware } Rob Allen ~ @akrabat

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Data transfer between middleware Read the attribute class GuardMiddleware { protected $allowedIps = [10.0.0.1, 192.168.0.1] public function __invoke($request, $response, $next) { $ipAddress = $request->getAttribute('ip_address'); if (!in_array($ipAddress, $this->allowedIps)) { return $response->withStatus(401); } return $next($request, $response); } } Rob Allen ~ @akrabat

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Data transfer between middleware Read the attribute class GuardMiddleware { protected $allowedIps = [10.0.0.1, 192.168.0.1] public function __invoke($request, $response, $next) { $ipAddress = $request->getAttribute('ip_address'); if (!in_array($ipAddress, $this->allowedIps)) { return $response->withStatus(401); } return $next($request, $response); } } Rob Allen ~ @akrabat

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Data transfer between middleware Read the attribute class GuardMiddleware { protected $allowedIps = [10.0.0.1, 192.168.0.1] public function __invoke($request, $response, $next) { $ipAddress = $request->getAttribute('ip_address'); if (!in_array($ipAddress, $this->allowedIps)) { return $response->withStatus(401); } return $next($request, $response); } } Rob Allen ~ @akrabat

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Data transfer between middleware Read the attribute class GuardMiddleware { protected $allowedIps = [10.0.0.1, 192.168.0.1] public function __invoke($request, $response, $next) { $ipAddress = $request->getAttribute('ip_address'); if (!in_array($ipAddress, $this->allowedIps)) { return $response->withStatus(401); } return $next($request, $response); } } Rob Allen ~ @akrabat

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Data transfer between middleware Read the attribute class GuardMiddleware { protected $allowedIps = [10.0.0.1, 192.168.0.1] public function __invoke($request, $response, $next) { $ipAddress = $request->getAttribute('ip_address'); if (!in_array($ipAddress, $this->allowedIps)) { return $response->withStatus(401); } return $next($request, $response); } } Rob Allen ~ @akrabat

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PSR-15 Two Interfaces from the Framework Interoperability Group: • Psr\Http\Server\MiddlewareInterface • Psr\Http\Server\RequestHandlerInterface Rob Allen ~ @akrabat

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PSR-15 MiddlewareInterface namespace Psr\Http\Server; use Psr\Http\Message\ResponseInterface; use Psr\Http\Message\ServerRequestInterface; interface MiddlewareInterface { public function process( ServerRequestInterface $request, RequestHandlerInterface $handler ) : ResponseInterface; } Rob Allen ~ @akrabat

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PSR-15 MiddlewareInterface namespace Psr\Http\Server; use Psr\Http\Message\ResponseInterface; use Psr\Http\Message\ServerRequestInterface; interface MiddlewareInterface { public function process( ServerRequestInterface $request, RequestHandlerInterface $handler ) : ResponseInterface; } Rob Allen ~ @akrabat

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PSR-15 MiddlewareInterface namespace Psr\Http\Server; use Psr\Http\Message\ResponseInterface; use Psr\Http\Message\ServerRequestInterface; interface MiddlewareInterface { public function process( ServerRequestInterface $request, RequestHandlerInterface $handler ) : ResponseInterface; } Rob Allen ~ @akrabat

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PSR-15 MiddlewareInterface namespace Psr\Http\Server; use Psr\Http\Message\ResponseInterface; use Psr\Http\Message\ServerRequestInterface; interface MiddlewareInterface { public function process( ServerRequestInterface $request, RequestHandlerInterface $handler ) : ResponseInterface; } Rob Allen ~ @akrabat

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PSR-15 MiddlewareInterface namespace Psr\Http\Server; use Psr\Http\Message\ResponseInterface; use Psr\Http\Message\ServerRequestInterface; interface MiddlewareInterface { public function process( ServerRequestInterface $request, RequestHandlerInterface $handler ) : ResponseInterface; } Rob Allen ~ @akrabat

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Structure of PSR-15 middleware class TimerMiddleware implements MiddlewareInterface { public function process($request, $handler) { $start = microtime(true); $response = $handler->handle($request); $taken = microtime(true) - $start; $response->getBody()->write(""); return $response; } } Rob Allen ~ @akrabat

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Structure of PSR-15 middleware class TimerMiddleware implements MiddlewareInterface { public function process($request, $handler) { $start = microtime(true); $response = $handler->handle($request); $taken = microtime(true) - $start; $response->getBody()->write(""); return $response; } } Rob Allen ~ @akrabat

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Structure of PSR-15 middleware class TimerMiddleware implements MiddlewareInterface { public function process($request, $handler) { $start = microtime(true); $response = $handler->handle($request); $taken = microtime(true) - $start; $response->getBody()->write(""); return $response; } } Rob Allen ~ @akrabat

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Structure of PSR-15 middleware class TimerMiddleware implements MiddlewareInterface { public function process($request, $handler) { $start = microtime(true); $response = $handler->handle($request); $taken = microtime(true) - $start; $response->getBody()->write(""); return $response; } } Rob Allen ~ @akrabat

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Structure of PSR-15 middleware class TimerMiddleware implements MiddlewareInterface { public function process($request, $handler) { $start = microtime(true); $response = $handler->handle($request); $taken = microtime(true) - $start; $response->getBody()->write(""); return $response; } } Rob Allen ~ @akrabat

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Structure of PSR-15 middleware class TimerMiddleware implements MiddlewareInterface { public function process($request, $handler) { $start = microtime(true); $response = $handler->handle($request); $taken = microtime(true) - $start; $response->getBody()->write(""); return $response; } } Rob Allen ~ @akrabat

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PSR-15 RequestHandler namespace Psr\Http\Server; use Psr\Http\Message\ResponseInterface; use Psr\Http\Message\ServerRequestInterface; interface RequestHandlerInterface { public function handle( ServerRequestInterface $request ): ResponseInterface; } Rob Allen ~ @akrabat

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PSR-15 RequestHandler namespace Psr\Http\Server; use Psr\Http\Message\ResponseInterface; use Psr\Http\Message\ServerRequestInterface; interface RequestHandlerInterface { public function handle( ServerRequestInterface $request ): ResponseInterface; } Rob Allen ~ @akrabat

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PSR-15 RequestHandler namespace Psr\Http\Server; use Psr\Http\Message\ResponseInterface; use Psr\Http\Message\ServerRequestInterface; interface RequestHandlerInterface { public function handle( ServerRequestInterface $request ): ResponseInterface; } Rob Allen ~ @akrabat

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A typical PSR-15 RequestHandler namespace App\Handler; // (use statements here) class HomePageHandler implements RequestHandlerInterface { public function handle(ServerRequestInterface $request) : ResponseInterface { return new HtmlResponse( '

Hello World

' ); } } Rob Allen ~ @akrabat

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A typical PSR-15 RequestHandler namespace App\Handler; // (use statements here) class HomePageHandler implements RequestHandlerInterface { public function handle(ServerRequestInterface $request) : ResponseInterface { return new HtmlResponse( '

Hello World

' ); } } Rob Allen ~ @akrabat

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A typical PSR-15 RequestHandler namespace App\Handler; // (use statements here) class HomePageHandler implements RequestHandlerInterface { public function handle(ServerRequestInterface $request) : ResponseInterface { return new HtmlResponse( '

Hello World

' ); } } Rob Allen ~ @akrabat

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Frameworks Rob Allen ~ @akrabat

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Zend Expressive: PSR-15 $app = new Zend\Expressive\Application(/* ... */); // add middleware $app->pipe(ErrorHandler::class); $app->pipe(RouteMiddleware::class); $app->pipe(IpAddress::class); $app->pipe(DispatchMiddleware::class); // add routes $app->get('/', App\Handler\HomePageHandler::class); $app->get('/api/ping', App\Handler\PingHandler::class); // run $app->run(); Rob Allen ~ @akrabat

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Slim Framework: PSR-7 $app = new Slim\App(); // add middleware $app->add(IpAddress::class); // add routes $app->get('/', App\Action\HomePageAction::class); $app->get('/api/ping', 'App\Controller\ApiController:pingAction'); // run $app->run(); Rob Allen ~ @akrabat

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Middleware components Search on Packagist • https://packagist.org/search/?q=psr-7%20middleware • https://packagist.org/search/?query=psr-15%20middleware Ones I use: • akrabat: ip-address-middleware & proxy-detection-middleware • tuupola: cors-middleware, slim-jwt-auth & slim-basic-auth • franzl: whoops-middleware • oscarotero: psr7-middlewares & psr15-middlewares Rob Allen ~ @akrabat

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Resources • https://www.php-fig.org/psr/psr-7 • https://www.php-fig.org/psr/psr-15 • https://www.php-fig.org/psr/psr-17 • https://mwop.net/blog/2015-01-26-psr-7-by-example.html • https://mwop.net/blog/2018-01-23-psr-15.html Rob Allen ~ @akrabat

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Thank you! Rob Allen http://akrabat.com - @akrabat