HTTP

The Hypertext Transfer Protocol (HTTP) is an application protocol for distributed, collaborative, hypermedia information systems.[1] HTTP is the foundation of data communication for the World Wide Web.

HTTP

HTTP

The HTTP header consists of:

• A request of response line
  • an http request line: method, url and version
  • a response line: version, code and response pharse
• A MIME header
  • A MIME header is comprised of zero or more MIME fields.
  • A MIME field is composed of a field name, a colon and zero or more field values.
  • The values in a field are separated by commas.

HTTP by Example

GET /GO1P-572/ HTTP/1.1
Host: com.apiom-test.s3-website-us-east-1.amazonaws.com
Connection: keep-alive
Cache-Control: max-age=0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
Upgrade-Insecure-Requests: 1
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_11_0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/45.0.2454.101 Safari/537.36
Accept-Encoding: gzip, deflate, sdch
Accept-Language: en-US,en;q=0.8,vi;q=0.6,cs;q=0.4
Cookie: __zlcmid=WYevYYlGONoaMB; _ga=GA1.2.1541119812.1441346929; _gat=1
If-None-Match: "db72b57d602ef57f571965257a13b1a2"
If-Modified-Since: Mon, 05 Oct 2015 04:35:00 GMT

HTTP/1.1 304 Not Modified
x-amz-id-2: HhdJ9sRg9afS0sp0nmnXJ+2IKUmExPOb7NPr4M7PwnHDaALBf1AopnnDn4E1ZouWPD1FHP6nhHs=
x-amz-request-id: FDA42C9D468DBFF9
Date: Mon, 05 Oct 2015 07:10:49 GMT
Last-Modified: Mon, 05 Oct 2015 04:35:00 GMT
x-amz-expiration: expiry-date="Tue, 20 Oct 2015 00:00:00 GMT", rule-id="Rule for the Entire Bucket"
ETag: "db72b57d602ef57f571965257a13b1a2"
Server: AmazonS3

Request Headers

Response Headers

HTTP by Example

HTTP Message in PHP

Client-side HTTP support

• PHP stream
• The cURL extension
• ext/http

Server-side HTTP support

• Server APIs (SAPI) to interpret incoming HTTP requests.
• SAPI design abstracts common input source such as cookies, query string agrs, and url-encode via super globals ($_COOKIE, $_GET, ...)

HTTP Message in PHP

Why bother?

• Projects use PHP's super-globals directly.
• Projects will create implementations from scratch.
• Projects may require a specific HTTP client/server library that provides HTTP message implementations.
• Projects may create adapters for common HTTP message implementations.

HTTP message interfaces

Message

• An HTTP message is either a request from a client to a server or a response from a server to a client.
• Both Psr\Http\Message\RequestInterface and Psr\Http\Message\ResponseInterface extend Psr\Http\Message\MessageInterface

HTTP message interfaces

HTTP Headers

• HTTP messages include case-insensitive header field names
• Headers are retrieved by name from classes implementing the MessageInterface in a case-insensitive manner
• Support multi-values

$message = $message->withHeader('foo', 'bar');

echo $message->getHeaderLine('foo');
// Outputs: bar

echo $message->getHeaderLine('FOO');
// Outputs: bar

$message = $message->withHeader('fOO', 'baz');
echo $message->getHeaderLine('foo');
// Outputs: baz

HTTP message interfaces

Streams

• HTTP messages consist of a start-line, headers, and a body.
• The body of an HTTP message can be very small or extremely large

HTTP message interfaces

Request Targets and URIs

• origin-form
• absolute-form
• authority-form
• asterisk-form

HTTP message interfaces

• Server-side Requests
• Uploaded files