psx/http

Mutable HTTP model and HTTP client implementation

v2.0.6 2018-03-18 18:42 UTC

README

About

This library contains well designed interfaces to describe HTTP message, middleware and client classes. It contains also corresponding reference implementations which can be used by every app which needs a solid HTTP stack. They are used by the PSX framework and Fusio.

We are aware that this overlaps with PSR-7 and PSR-15 but we think that those specs have made some bad design decisions and this project is here to provide an alternative. It is always good to have diversity and evolution will show which is the better solution. Also we should note the fitting XKDC.

HTTP

RequestInterface

+ getRequestTarget(): string
+ setRequestTarget(string $requestTarget)
+ getMethod(): string
+ setMethod(string $method)
+ getUri(): UriInterface
+ setUri(UriInterface $uri)
+ getAttributes(): string|null
+ getAttribute(string $name)
+ setAttribute(string $name, mixed $value)
+ removeAttribute(string $name)

ResponseInterface

+ getStatusCode(): integer
+ getReasonPhrase(): string
+ setStatus(integer $code, string $reasonPhrase = null)

MessageInterface

+ getProtocolVersion(): string
+ setProtocolVersion(string $protocol)
+ getHeaders(): array
+ setHeaders(array $headers)
+ hasHeader(string $name): bool
+ getHeader(string $name): string|null
+ getHeaderLines(string $name): array
+ setHeader(string $name, string $value)
+ addHeader(string $name, string $value)
+ removeHeader(string $name)
+ getBody(): StreamInterface
+ setBody(StreamInterface $body)

HTTP Body

StreamInterface

+ close()
+ detach(): resource
+ getSize(): integer
+ tell(): integer
+ eof(): boolean
+ isSeekable(): boolean
+ seek(integer $offset, $whence = SEEK_SET)
+ rewind()
+ isWritable(): boolean
+ write(string $string): integer
+ isReadable(): boolean
+ read(integer $length): string
+ getContents(): string
+ getMetadata(string $key = null): string

HTTP Middleware

FilterInterface

+ handle(RequestInterface $request, ResponseInterface $response, FilterChainInterface $filterChain)

FilterChainInterface

+ on(FilterInterface|\Closure $filter)
+ handle(RequestInterface $request, ResponseInterface $response)

HTTP Client

ClientInterface

+ request(RequestInterface $request, OptionsInterface $options = null)

OptionsInterface

+ getAllowRedirects(): boolean
+ getCert(): string
+ getProxy(): string
+ getSslKey(): string
+ getVerify(): boolean
+ getTimeout(): float
+ getVersion(): float

Examples

Middleware

The following shows a simple middleware which always returns the response body Hello World!:

<?php

use PSX\Http;
use PSX\Http\Server;

$chain = new Http\Filter\FilterChain();

// enforce user agent in HTTP request
$chain->on(new Http\Filter\UserAgentEnforcer());

// display maintenance file if available
$chain->on(new Http\Filter\Backstage(__DIR__ . '/.maintenance.html'));

// closure middleware
$chain->on(function(Http\RequestInterface $request, Http\ResponseInterface $response, Http\FilterChainInterface $filterChain){
    // get query parameter
    $request->getUri()->getParameter('foo');
    
    // set header
    $response->setHeader('X-Foo', 'bar');
    
    // write data to the body
    $response->getBody()->write('Hello World!');
    
    $filterChain->handle($request, $response);
});

// create global HTTP request and response
$request  = (new Server\RequestFactory())->createRequest();
$response = (new Server\ResponseFactory())->createResponse();

// start middleware chain
$chain->handle($request, $response);

// send response
(new Server\Sender())->send($response);

Client

The following sends a HTTP GET request to google:

<?php

use PSX\Http\Client;
use PSX\Http\Exception\StatusCodeException;

// create HTTP client
$client = new Client\Client();

// build request
$request = new Client\GetRequest('http://google.com', ['Accept' => 'text/html']);

// send request
$response = $client->request($request);

// check response
if ($response->getStatusCode() == 200) {
    // get header
    $contentType = $response->getHeader('Content-Type');

    // output response body
    echo (string) $response->getBody();
} else {
    // the client never throws an exception for unsuccessful response codes but
    // you can do this explicit
    StatusCodeException::throwOnError($response);
}

Uploads

Example how to handle file uploads:

<?php

use PSX\Http;
use PSX\Http\Server;

$chain = new Http\Filter\FilterChain();

// closure middleware
$chain->on(function(Http\RequestInterface $request, Http\ResponseInterface $response, Http\FilterChainInterface $filterChain){
    // get body
    $body = $request->getBody();

    if ($body instanceof Http\Stream\MultipartStream) {
        // move uploaded file to a new location
        $body->getPart('userfile')->move('/home/new/file.txt');

        // or access the file directly through the normal stream functions
        //$body->getPart('userfile')->read(32);

        // write data to the body
        $response->getBody()->write('Upload successful!');
    } else {
        // no upload so show form
        $html = <<<'HTML'
<!-- The data encoding type, enctype, MUST be specified as below -->
<form enctype="multipart/form-data" action="" method="POST">
    <!-- MAX_FILE_SIZE must precede the file input field -->
    <input type="hidden" name="MAX_FILE_SIZE" value="30000" />
    <!-- Name of input element determines name in $_FILES array -->
    Send this file: <input name="userfile" type="file" />
    <input type="submit" value="Send File" />
</form>
HTML;

        $response->getBody()->write($html);
    }

    $filterChain->handle($request, $response);
});

// create global HTTP request and response
$request  = (new Server\RequestFactory())->createRequest();
$response = (new Server\ResponseFactory())->createResponse();

// start middleware chain
$chain->handle($request, $response);

// send response
(new Server\Sender())->send($response);

Distinction

PSR-7

  • The classes are mutable (set* instead of with*), you can change the state of the object.
  • There is no ServerRequestInterface and UploadedFileInterface
  • There is only a single way to access query parameters
  • getHeader returns a string instead of an array which is the 80% case

Thoughts

  • Because PSR-7 is immutable PSR-15 must have the fn(req): res signature since it is not possible to change the response object.
  • The middleware needs to know how to create a HTTP response instance. Because of this you can't inject a different response implementation into your middleware stack. As workaround we see a HTTP factory PSR, but we think this is a code-smell.
  • If your app uses a PHP server like Swoole you want to wrap the Swoole response object and pass it to the middleware to handle also streaming use cases.
  • Immutability forces a design on your application you have i.e. not the option to use the double-pass middleware signature.
  • Since PHP has no immutability on the language level we must always copy the object and change a specific value which is bad for memory / performance.
  • It is really difficult to migrate legacy applications to the fn(req): res middleware style since most applications today work with a mutable HTTP object.
  • PSR-7 is actually not fully immutable since the body is always mutable