advanced.md

# HTTP Client Advanced Usage

## HTTP redirections

`Zend\Http\Client` automatically handles HTTP redirections, and by default
will follow up to 5 redirections. This can be changed by setting the
`maxredirects` configuration parameter.

According to the HTTP/1.1 RFC, HTTP 301 and 302 responses should be treated by
the client by resending the same request to the specified location, using the
same request method. However, most clients to not implement this and always use
a `GET` request when redirecting. By default, `Zend\Http\Client` does the same;
when redirecting on a 301 or 302 response, all query and body parameters are
reset, and a `GET` request is sent to the new location. This behavior can be
changed by setting the `strictredirects` configuration parameter to boolean
`TRUE`:

```php
// Strict Redirections
$client->setOptions(['strictredirects' => true]);

// Non-strict Redirections
$client->setOptions(['strictredirects' => false]);
```

You can always get the number of redirections done after sending a request
using the `getRedirectionsCount()` method.

## Adding cookies and using cookie persistence

`Zend\Http\Client` provides an interface for adding cookies to your request, so
that no direct header modification is required. Cookies can be added using
either the addCookie() or `setCookies()` method. `addCookie()` can accept
either a name and value, a `SetCookie` header instance, or an array of
`SetCookie` header instances.

```php
use Zend\Http\Header\SetCookie;

// Basic usage: provide a cookie name and cookie value:
$client->addCookie('flavor', 'chocolate chips');

// Or provide a SetCookie instance:
$cookie = SetCookie::fromString('Set-Cookie: flavor=chocolate%20chips');
$client->addCookie($cookie);

// Multiple cookies can be set at once by providing an
// array of SetCookie instances:
$cookies = [
    SetCookie::fromString('Set-Cookie: flavorOne=chocolate%20chips'),
    SetCookie::fromString('Set-Cookie: flavorTwo=vanilla'),
];
$client->addCookie($cookies);
```

The `setCookies()` method works in a similar manner, except that it requires an
array of cookie name/value pairs as its only argument, and also clears the
cookie container before adding the new cookies:

```php
// setCookies accepts an array of cookie values as $name => $value
$client->setCookies([
    'flavor' => 'chocolate chips',
    'amount' => 10,
]);
```

See the [Headers documentation](../headers.md#setcookie) for more detail on the
`SetCookie` class.

### Enabling Cookie Stickiness

`Zend\Http\Client` also provides a means for simplifying cookie "stickiness"
— i.e., having the client internally store all sent and received cookies,
and resending them on subsequent requests. — via the `Zend\Http\Cookies`
class. This is useful when you need to log in to a remote site first and
receive an authentication or session ID cookie before sending further requests.

```php
$headers = $client->getRequest()->getHeaders();
$cookies = new Zend\Http\Cookies($headers);

// First request: log in and start a session
$client->setUri('http://example.com/login.php');
$client->setParameterPost(['user' => 'h4x0r', 'password' => 'l33t']);
$client->setMethod('POST');

$response = $client->getResponse();
$cookies->addCookiesFromResponse($response, $client->getUri());

// Now we can send our next request
$client->setUri('http://example.com/read_member_news.php');
$client->setCookies($cookies->getMatchingCookies($client->getUri()));
$client->setMethod('GET');
```

See the chapter on [cookies](cookies.md) for more detail.

## Setting custom request headers

Setting custom headers is performed by first fetching the header container from
the client's `Zend\Http\Request` instance. This `Headers` container offers a
number of methods for setting headers:

```php
use Zend\Http\Header;

// Fetch the container
$headers = $client->getRequest()->getHeaders();

// Setting a single header using a name and value. Will not overwrite any //
previously-added headers of the same name.
$headers->addHeaderLine('Host', 'www.example.com');

// You can also use a full header line:
$headers->addHeaderLine('Host: www.example.com');

// Sometimes you may want to use a HeaderInterface instance:
$headers->addHeader(Header\Host::fromString('Host: www.example.com'));

// You can also add multiple headers at once by passing an
// array to addHeaders() using any of the formats below:
$headers->addHeaders([
    // Zend\Http\Header\* instance:
    Header\Host::fromString('Host: www.example.com'),

    // Header name/value pair:
    'Cookie' => 'PHPSESSID=1234567890abcdef1234567890abcdef',

    // Raw header string:
    'Cookie: language=he',
]);
```

`Zend\Http\Client` also provides a convenience method for setting request
headers, `setHeaders()`.  This method will create a new header container, add
the specified headers, and then store the new header container in its
`Zend\Http\Request` instance. As a consequence, any pre-existing headers will
be erased:

```php
use Zend\Http\Header;

// Setting multiple headers via the client; removes all existing headers,
// replacing the request header container with the following:
$client->setHeaders([
    Zend\Http\Header\Host::fromString('Host: www.example.com'),
    ['Accept-Encoding' => 'gzip,deflate'],
    'X-Powered-By: Zend Framework',
]);
```

## File uploads

You can upload files through HTTP using the `setFileUpload()` method. This
method takes a file name as the first parameter, a form name as the second
parameter, and data as a third optional parameter. If the third data parameter
is `NULL`, the first file name parameter is considered to be a real file on
disk, and `Zend\Http\Client` will try to read this file and upload it. If the
data parameter is not `NULL`, the first file name parameter will be sent as the
file name, but no actual file needs to exist on the disk. The second form name
parameter is always required, and is equivalent to the "name" attribute of an
`<input>` tag, if the file was to be uploaded through an HTML form. A fourth
optional parameter provides the file's `Content-Type`. If not specified, and
`Zend\Http\Client` reads the file from the disk, the `mime_content_type()`
function will be used to guess the file's content type, if it is available. In
any case, the default MIME type will be `application/octet-stream`.

```php
// Uploading arbitrary data as a file:
$text = 'this is some plain text';
$client->setFileUpload('some_text.txt', 'upload', $text, 'text/plain');

// Uploading an existing file:
$client->setFileUpload('/tmp/Backup.tar.gz', 'bufile');

// Send the files:
$client->setMethod('POST');
$client->send();
```

In the first example, the `$text` variable is uploaded and will be available as
`$_FILES['upload']` on the server side. In the second example, the existing
file `/tmp/Backup.tar.gz` is uploaded to the server and will be available as
`$_FILES['bufile']`. The content type will be guessed automatically if
possible, defaulting to `application/octet-stream`.

> ### Uploading files
>
> When uploading files, the HTTP request `Content-Type` is automatically set to
> `multipart/form-data`.  Keep in mind that you must send a POST or PUT request
> in order to upload files; most servers will ignore the request body on other
> request methods.

## Sending raw POST data

You can send raw POST data via `Zend\Http\Client` using the `setRawBody()`
method. This method takes one parameter: the data to send in the request body.
When sending raw POST data, it is advisable to also set the encoding type using
`setEncType()`.

```php
$xml = '<book>'
    . '  <title>Islands in the Stream</title>'
    . '  <author>Ernest Hemingway</author>'
    . '  <year>1970</year>'
    . '</book>';
$client->setMethod('POST');
$client->setRawBody($xml);
$client->setEncType('text/xml');
$client->send();
```

The data should be available on the server side through PHP's `php://input`
stream.

> ### Raw POST data overrides other content
>
> Setting raw POST data for a request will override any POST parameters or file
> uploads; you should not try to use both on the same request. Keep in mind
> that most servers will ignore the request body unless you send a POST
> request.

## HTTP authentication

Currently, `Zend\Http\Client` only supports basic HTTP authentication. This feature is utilized
using the `setAuth()` method, or by specifying a username and a password in the URI. The `setAuth()`
method takes 3 parameters: the user name, the password and an optional authentication type
parameter.

```php
use Zend\Http\Client;

// Using basic authentication
$client->setAuth('shahar', 'myPassword!', Client::AUTH_BASIC);

// Since basic auth is default, you can just do this:
$client->setAuth('shahar', 'myPassword!');

// You can also specify username and password in the URI
$client->setUri('http://christer:secret@example.com');
```

## Sending multiple requests with the same client

`Zend\Http\Client` was also designed specifically to handle several consecutive
requests with the same object. This is useful in cases where a script requires
data to be fetched from several places, or when accessing a specific HTTP
resource requires logging in and obtaining a session cookie, for example.

When performing several requests to the same host, it is highly recommended to
enable the 'keepalive' configuration flag. This way, if the server supports
keep-alive connections, the connection to the server will only be closed once
all requests are done and the `Client` object is destroyed. This prevents the
overhead of opening and closing TCP connections to the server.

When you perform several requests with the same client, but want to make sure
all the request-specific parameters are cleared, you should use the
`resetParameters()` method. This ensures that GET and POST parameters, request
body, and request headers are reset and are not reused in the next request.

> ### Resetting parameters
>
> Note that cookies are not reset by default when the `resetParameters()`
> method is used. To clean all cookies as well, use `resetParameters(true)`, or
> call `clearCookies()` after calling `resetParameters()`.

Another feature designed specifically for consecutive requests is the
`Zend\Http\Cookies` object.  This "Cookie Jar" allow you to save cookies set by
the server in a request, and send them back on consecutive requests
transparently. This allows, for example, going through an authentication
request before sending the actual data-fetching request.

If your application requires one authentication request per user, and
consecutive requests might be performed in more than one script in your
application, it might be a good idea to store the `Cookies` object in the user's
session. This way, you will only need to authenticate the user once every
session.

### Performing consecutive requests with one client

```php
use Zend\Http\Client;
use Zend\Http\Cookies;

// First, instantiate the client
$client = new Client(
    'http://www.example.com/fetchdata.php',
    ['keepalive' => true]
);

// Do we have the cookies stored in our session?
if (isset($_SESSION['cookiejar'])
    && $_SESSION['cookiejar'] instanceof Cookies
) {
    $cookieJar = $_SESSION['cookiejar'];
} else {
    // If we don't, authenticate and store cookies
    $client->setUri('http://www.example.com/login.php');
    $client->setParameterPost([
        'user' => 'shahar',
        'pass' => 'somesecret',
    ]);
    $response = $client->setMethod('POST')->send();
    $cookieJar = Cookies::fromResponse($response);

    // Now, clear parameters and set the URI to the original one
    // (note that the cookies that were set by the server are now
    // stored in the jar)
    $client->resetParameters();
    $client->setUri('http://www.example.com/fetchdata.php');
}

// Add the cookies to the new request
$client->setCookies($cookieJar->getMatchingCookies($client->getUri()));
$response = $client->setMethod('GET')->send();

// Store cookies in session, for next page
$_SESSION['cookiejar'] = $cookieJar;
```

## Data streaming

By default, `Zend\Http\Client` accepts and returns data as PHP strings.
However, in many cases there are big files to be received, thus keeping them in
memory might be unnecessary or too expensive. For these cases,
`Zend\Http\Client` supports writing data to files (streams).

In order to receive data from the server as stream, use `setStream()`. The
single, optional argument specifies the filename where the data will be stored.
If the argument is just `TRUE` (default), a temporary file will be used and
will be deleted once the response object is destroyed. Setting the argument to
`FALSE` disables the streaming functionality.

When using streaming, the `send()` method will return an object of class
`Zend\Http\Response\Stream`, which has two useful methods: `getStreamName()`
will return the name of the file where the response is stored, and
`getStream()` will return stream from which the response could be read.

You can either write the response to pre-defined file, or use temporary file
for storing it and send it out or write it to another file using regular stream
functions.

```php
$client-setStream(); // will use temp file
$response = $client-send();

// copy file:
copy($response-getStreamName(), 'my/downloads/file');

// use stream:
$fp = fopen('my/downloads/file2', 'w');
stream_copy_to_stream($response-getStream(), $fp);

// write to an existing file:
$client-setStream('my/downloads/myfile')-send();
```