Guzzle and PSR-7

Guzzle utilizes PSR-7 as the HTTP message interface. This allows Guzzle to work with any other library that utilizes PSR-7 message interfaces.

Guzzle is an HTTP client that sends HTTP requests to a server and receives HTTP responses. Both requests and responses are referred to as messages.

Guzzle relies on the guzzlehttp/psr7 Composer package for its message implementation of PSR-7.

You can create a request using the GuzzleHttp\Psr7\Request class:

use GuzzleHttp\Psr7\Request;

$request = new Request('GET', 'http://httpbin.org/get');

// You can provide other optional constructor arguments.
$headers = ['X-Foo' => 'Bar'];
$body = 'hello!';
$request = new Request('PUT', 'http://httpbin.org/put', $headers, $body);

You can create a response using the GuzzleHttp\Psr7\Response class:

use GuzzleHttp\Psr7\Response;

// The constructor requires no arguments.
$response = new Response();
echo $response->getStatusCode(); // 200
echo $response->getProtocolVersion(); // 1.1

// You can supply any number of optional arguments.
$status = 200;
$headers = ['X-Foo' => 'Bar'];
$body = 'hello!';
$protocol = '1.1';
$response = new Response($status, $headers, $body, $protocol);

Headers

Both request and response messages contain HTTP headers.

Accessing Headers

You can check if a request or response has a specific header using the hasHeader() method.

use GuzzleHttp\Psr7;

$request = new Psr7\Request('GET', '/', ['X-Foo' => 'bar']);

if ($request->hasHeader('X-Foo')) {
    echo 'It is there';
}

You can retrieve all the header values as an array of strings using getHeader().

$request->getHeader('X-Foo'); // ['bar']

// Retrieving a missing header returns an empty array.
$request->getHeader('X-Bar'); // []

You can iterate over the headers of a message using the getHeaders() method.

foreach ($request->getHeaders() as $name => $values) {
    echo $name . ': ' . implode(', ', $values) . "\r\n";
}

Complex Headers

Some headers contain additional key value pair information. For example, Link headers contain a link and several key value pairs:

<http://foo.com>; rel="thing"; type="image/jpeg"

Guzzle provides a convenience feature that can be used to parse these types of headers:

use GuzzleHttp\Psr7;

$request = new Psr7\Request('GET', '/', [
    'Link' => '<http:/.../front.jpeg>; rel="front"; type="image/jpeg"'
]);

$parsed = Psr7\parse_header($request->getHeader('Link'));
var_export($parsed);

Will output:

array (
  0 =>
  array (
    0 => '<http:/.../front.jpeg>',
    'rel' => 'front',
    'type' => 'image/jpeg',
  ),
)

The result contains a hash of key value pairs. Header values that have no key (i.e., the link) are indexed numerically while headers parts that form a key value pair are added as a key value pair.

Body

Both request and response messages can contain a body.

You can retrieve the body of a message using the getBody() method:

$response = GuzzleHttp\get('http://httpbin.org/get');
echo $response->getBody();
// JSON string: { ... }

The body used in request and response objects is a Psr\Http\Message\StreamInterface. This stream is used for both uploading data and downloading data. Guzzle will, by default, store the body of a message in a stream that uses PHP temp streams. When the size of the body exceeds 2 MB, the stream will automatically switch to storing data on disk rather than in memory (protecting your application from memory exhaustion).

The easiest way to create a body for a message is using the stream_for function from the GuzzleHttp\Psr7 namespace -- GuzzleHttp\Psr7\stream_for. This function accepts strings, resources, callables, iterators, other streamables, and returns an instance of Psr\Http\Message\StreamInterface.

The body of a request or response can be cast to a string or you can read and write bytes off of the stream as needed.

use GuzzleHttp\Stream\Stream;
$response = $client->request('GET', 'http://httpbin.org/get');

echo $response->getBody()->read(4);
echo $response->getBody()->read(4);
echo $response->getBody()->read(1024);
var_export($response->eof());

Requests

Requests are sent from a client to a server. Requests include the method to be applied to a resource, the identifier of the resource, and the protocol version to use.

Request Methods

When creating a request, you are expected to provide the HTTP method you wish to perform. You can specify any method you'd like, including a custom method that might not be part of RFC 7231 (like "MOVE").

// Create a request using a completely custom HTTP method
$request = new \GuzzleHttp\Psr7\Request('MOVE', 'http://httpbin.org/move');

echo $request->getMethod();
// MOVE

You can create and send a request using methods on a client that map to the HTTP method you wish to use.

GET
$client->get('http://httpbin.org/get', [/** options **/])
POST
$client->post('http://httpbin.org/post', [/** options **/])
HEAD
$client->head('http://httpbin.org/get', [/** options **/])
PUT
$client->put('http://httpbin.org/put', [/** options **/])
DELETE
$client->delete('http://httpbin.org/delete', [/** options **/])
OPTIONS
$client->options('http://httpbin.org/get', [/** options **/])
PATCH
$client->patch('http://httpbin.org/put', [/** options **/])

For example:

$response = $client->patch('http://httpbin.org/patch', ['body' => 'content']);

Request URI

The request URI is represented by a Psr\Http\Message\UriInterface object. Guzzle provides an implementation of this interface using the GuzzleHttp\Psr7\Uri class.

When creating a request, you can provide the URI as a string or an instance of Psr\Http\Message\UriInterface.

$response = $client->request('GET', 'http://httpbin.org/get?q=foo');

Scheme

The scheme of a request specifies the protocol to use when sending the request. When using Guzzle, the scheme can be set to "http" or "https".

$request = new Request('GET', 'http://httpbin.org');
echo $request->getUri()->getScheme(); // http
echo $request->getUri(); // http://httpbin.org/get

Host

The host is accessible using the URI owned by the request or by accessing the Host header.

$request = new Request('GET', 'http://httpbin.org');
echo $request->getUri()->getHost(); // httpbin.org
echo $request->getHeader('Host'); // httpbin.org

Port

No port is necessary when using the "http" or "https" schemes.

$request = new Request('GET', 'http://httpbin.org:8080');
echo $request->getUri()->getPort(); // 8080
echo $request->getUri(); // http://httpbin.org:8080

Path

The path of a request is accessible via the URI object.

$request = new Request('GET', 'http://httpbin.org/get');
echo $request->getUri()->getPath(); // /get

The contents of the path will be automatically filtered to ensure that only allowed characters are present in the path. Any characters that are not allowed in the path will be percent-encoded according to RFC 3986 section 3.3

Query string

The query string of a request can be accessed using the getQuery() of the URI object owned by the request.

$request = new Request('GET', 'http://httpbin.org/?foo=bar');
echo $request->getUri()->getQuery(); // foo=bar

The contents of the query string will be automatically filtered to ensure that only allowed characters are present in the query string. Any characters that are not allowed in the query string will be percent-encoded according to RFC 3986 section 3.4

Responses

Responses are the HTTP messages a client receives from a server after sending an HTTP request message.

Start-Line

The start-line of a response contains the protocol and protocol version, status code, and reason phrase.

$client = new \GuzzleHttp\Client();
$response = $client->request('GET', 'http://httpbin.org/get');

echo $response->getStatusCode(); // 200
echo $response->getReasonPhrase(); // OK
echo $response->getProtocolVersion(); // 1.1

Body

As described earlier, you can get the body of a response using the getBody() method.

$body = $response->getBody()) {
echo $body;
// Cast to a string: { ... }
$body->seek(0);
// Rewind the body
$body->read(1024);
// Read bytes of the body

Streams

Guzzle uses PSR-7 stream objects to represent request and response message bodies. These stream objects allow you to work with various types of data all using a common interface.

HTTP messages consist of a start-line, headers, and a body. The body of an HTTP message can be very small or extremely large. Attempting to represent the body of a message as a string can easily consume more memory than intended because the body must be stored completely in memory. Attempting to store the body of a request or response in memory would preclude the use of that implementation from being able to work with large message bodies. The StreamInterface is used in order to hide the implementation details of where a stream of data is read from or written to.

The PSR-7 Psr\Http\Message\StreamInterface exposes several methods that enable streams to be read from, written to, and traversed effectively.

Streams expose their capabilities using three methods: isReadable(), isWritable(), and isSeekable(). These methods can be used by stream collaborators to determine if a stream is capable of their requirements.

Each stream instance has various capabilities: they can be read-only, write-only, read-write, allow arbitrary random access (seeking forwards or backwards to any location), or only allow sequential access (for example in the case of a socket or pipe).

Guzzle uses the guzzlehttp/psr7 package to provide stream support. More information on using streams, creating streams, converting streams to PHP stream resource, and stream decorators can be found in the Guzzle PSR-7 documentation.

Creating Streams

The best way to create a stream is using the GuzzleHttp\Psr7\stream_for function. This function accepts strings, resources returned from fopen(), an object that implements __toString(), iterators, callables, and instances of Psr\Http\Message\StreamInterface.

use GuzzleHttp\Psr7;

$stream = Psr7\stream_for('string data');
echo $stream;
// string data
echo $stream->read(3);
// str
echo $stream->getContents();
// ing data
var_export($stream->eof());
// true
var_export($stream->tell());
// 11

You can create streams from iterators. The iterator can yield any number of bytes per iteration. Any excess bytes returned by the iterator that were not requested by a stream consumer will be buffered until a subsequent read.

use GuzzleHttp\Psr7;

$generator = function ($bytes) {
    for ($i = 0; $i < $bytes; $i++) {
        yield '.';
    }
};

$iter = $generator(1024);
$stream = Psr7\stream_for($iter);
echo $stream->read(3); // ...

Metadata

Streams expose stream metadata through the getMetadata() method. This method provides the data you would retrieve when calling PHP's stream_get_meta_data() function, and can optionally expose other custom data.

use GuzzleHttp\Psr7;

$resource = fopen('/path/to/file', 'r');
$stream = Psr7\stream_for($resource);
echo $stream->getMetadata('uri');
// /path/to/file
var_export($stream->isReadable());
// true
var_export($stream->isWritable());
// false
var_export($stream->isSeekable());
// true

Stream Decorators

Adding custom functionality to streams is very simple with stream decorators. Guzzle provides several built-in decorators that provide additional stream functionality.