Added PSR-7 Interfaces brief explanations and Basic Usage Guide

README.md

@@ -10,4 +10,7 @@ interface that describes a HTTP message. See the specification for more details.
 Usage
 -----
 
-We'll certainly need some stuff in here.
+Before reading the usage guide we recommend reading the PSR-7 interfaces method list:
+
+* [`PSR-7 Interfaces Method List`](docs/PSR7-Interfaces.md)
+* [`PSR-7 Usage Guide`](docs/PSR7-Usage.md)

docs/PSR7-Interfaces.md

@@ -0,0 +1,129 @@
+#Interfaces
+
+The purpose of this list is to help in finding the methods when working with PSR-7. This can be considered as a cheatsheet for PSR-7 interfaces.
+
+The interfaces defined in PSR-7 are the following:
+
+| Class Name | Description |
+|---|---|
+| [Psr\Http\Message\MessageInterface](http://www.php-fig.org/psr/psr-7/#psrhttpmessagemessageinterface) | Representation of a HTTP message |
+| [Psr\Http\Message\RequestInterface](http://www.php-fig.org/psr/psr-7/#psrhttpmessagerequestinterface) | Representation of an outgoing, client-side request. |
+| [Psr\Http\Message\ServerRequestInterface](http://www.php-fig.org/psr/psr-7/#psrhttpmessageserverrequestinterface) | Representation of an incoming, server-side HTTP request. | 
+| [Psr\Http\Message\ResponseInterface](http://www.php-fig.org/psr/psr-7/#psrhttpmessageresponseinterface) | Representation of an outgoing, server-side response. |
+| [Psr\Http\Message\StreamInterface](http://www.php-fig.org/psr/psr-7/#psrhttpmessagestreaminterface) | Describes a data stream |
+| [Psr\Http\Message\UriInterface](http://www.php-fig.org/psr/psr-7/#psrhttpmessageuriinterface) | Value object representing a URI. |
+| [Psr\Http\Message\UploadedFileInterface](http://www.php-fig.org/psr/psr-7/#psrhttpmessageuploadedfileinterface) | Value object representing a file uploaded through an HTTP request. |
+
+## `Psr\Http\Message\MessageInterface` Methods
+
+| Method Name                        | Description | Notes |
+|------------------------------------| ----------- | ----- |
+| `getProtocolVersion()`             | Gets HTTP protocol version          |  1.0 or 1.1 |
+| `withProtocolVersion($version)`    | Sets HTTP protocol version          |      |
+| `getHeaders()`                     | Gets all HTTP Headers               | [Request Header List](https://en.wikipedia.org/wiki/List_of_HTTP_header_fields#Request_fields), [Response Header List](https://en.wikipedia.org/wiki/List_of_HTTP_header_fields#Response_fields)      |
+| `hasHeader($name)`                 | Checks if HTTP Header with given name exists  | |
+| `getHeader($name)`                 | Retrieves a array with the values for a single header | |
+| `getHeaderLine($name)`             | Retrieves a comma-separated string of the values for a single header |  |
+| `withHeader($name, $value)`        | Sets a HTTP Header | If header already exists, value will be overwritten |
+| `withAddedHeader($name, $value)`   | Appends value to given header | If header already exists value will be appended, if not a new header will be created |
+| `withoutHeader($name)`             | Removes HTTP Header with given name| |
+| `getBody()`                        | Get the HTTP Message Body | Returns object implementing `StreamInterface`|
+| `withBody(StreamInterface $body)`  | Sets the HTTP Message Body | |
+
+
+## `Psr\Http\Message\RequestInterface` Methods
+
+Same methods as `Psr\Http\Message\MessageInterface`  + the following methods:
+| Method Name                        | Description | Notes |
+|------------------------------------| ----------- | ----- |
+| `getRequestTarget()`                | Retrieves the message's request target              | origin-form, absolute-form, authority-form, asterisk-form ([RFC7230](https://www.rfc-editor.org/rfc/rfc7230.txt)) |
+| `withRequestTarget($requestTarget)` | Return an instance with the specific request-target |      |
+| `getMethod()`                       | Retrieves the HTTP method of the request.  |  GET, HEAD, POST, PUT, DELETE, CONNECT, OPTIONS, TRACE (defined in [RFC7231](https://tools.ietf.org/html/rfc7231)), PATCH (defined in [RFC5789](https://tools.ietf.org/html/rfc5789)) |
+| `withMethod($method)`               | Return an instance with the provided HTTP method  | |
+| `getUri()`                 | Retrieves the URI instance | |
+| `withUri(UriInterface $uri, $preserveHost = false)` | Returns an instance with the provided URI |  |
+
+
+## `Psr\Http\Message\ServerRequestInterface` Methods
+
+Same methods as `Psr\Http\Message\RequestInterface`  + the following methods:
+
+| Method Name                        | Description | Notes |
+|------------------------------------| ----------- | ----- |
+| `getServerParams() `               | Retrieve server parameters  | Typically derived from `$_SERVER`  |
+| `getCookieParams()`                | Retrieves cookies sent by the client to the server. | Typically derived from `$_COOKIES` |
+| `withCookieParams(array $cookies)` |  Return an instance with the specified cookies      |   | 
+| `withQueryParams(array $query)` | Return an instance with the specified query string arguments  |  |
+| `getUploadedFiles()` | Retrieve normalized file upload data  |  |
+| `withUploadedFiles(array $uploadedFiles)` | Create a new instance with the specified uploaded files  |  |
+| `getParsedBody()` | Retrieve any parameters provided in the request body  |  |
+| `withParsedBody($data)` | Return an instance with the specified body parameters  |  |
+| `getAttributes()` | Retrieve attributes derived from the request  |  |
+| `getAttribute($name, $default = null)` | Retrieve a single derived request attribute  |  |
+| `withAttribute($name, $value)` | Return an instance with the specified derived request attribute  |  |
+| `withoutAttribute($name)` | Return an instance that removes the specified derived request attribute  |  |
+
+## `Psr\Http\Message\ResponseInterface` Methods:
+
+Same methods as `Psr\Http\Message\MessageInterface`  + the following methods:
+
+| Method Name                        | Description | Notes |
+|------------------------------------| ----------- | ----- |
+| `getStatusCode()` | Gets the response status code. | |
+| `withStatus($code, $reasonPhrase = '')` | Return an instance with the specified status code and, optionally, reason phrase. | |
+| `getReasonPhrase()` | Gets the response reason phrase associated with the status code. | |
+
+##  `Psr\Http\Message\StreamInterface` Methods
+
+| Method Name                        | Description | Notes |
+|------------------------------------| ----------- | ----- |
+| `__toString()` | Reads all data from the stream into a string, from the beginning to end. | |
+| `close()` | Closes the stream and any underlying resources. | |
+| `detach()` | Separates any underlying resources from the stream. | |
+| `getSize()` | Get the size of the stream if known. | |
+| `eof()` | Returns true if the stream is at the end of the stream.| |
+| `isSeekable()` |  Returns whether or not the stream is seekable. | |
+| `seek($offset, $whence = SEEK_SET)` | Seek to a position in the stream. | |
+| `rewind()` | Seek to the beginning of the stream. | |
+| `isWritable()` | Returns whether or not the stream is writable. | |
+| `write($string)` | Write data to the stream. | |
+| `isReadable()` | Returns whether or not the stream is readable. | |
+| `read($length)` | Read data from the stream. | |
+| `getContents()` | Returns the remaining contents in a string | |
+| `getMetadata($key = null)()` | Get stream metadata as an associative array or retrieve a specific key. | |
+
+## `Psr\Http\Message\UriInterface` Methods
+
+| Method Name                        | Description | Notes |
+|------------------------------------| ----------- | ----- |
+| `getScheme()` | Retrieve the scheme component of the URI. | |
+| `getAuthority()` | Retrieve the authority component of the URI. | |
+| `getUserInfo()` | Retrieve the user information component of the URI. | |
+| `getHost()` | Retrieve the host component of the URI. | |
+| `getPort()` | Retrieve the port component of the URI. | |
+| `getPath()` | etrieve the path component of the URI. | |
+| `getQuery()` | Retrieve the query string of the URI. | |
+| `getFragment()` | Retrieve the fragment component of the URI. | |
+| `withScheme($scheme)` | Return an instance with the specified scheme. | |
+| `withUserInfo($user, $password = null)` | Return an instance with the specified user information. | |
+| `withHost($host)` | Return an instance with the specified host. | |
+| `withPort($port)` | Return an instance with the specified port. | |
+| `withPath($path)` | Return an instance with the specified path. | |
+| `withQuery($query)` | Return an instance with the specified query string. | |
+| `withFragment($fragment)` | Return an instance with the specified URI fragment. | |
+| `__toString()` | Return the string representation as a URI reference. | |
+
+`Psr\Http\Message\UploadedFileInterface`
+
+| Method Name                        | Description | Notes |
+|------------------------------------| ----------- | ----- |
+| `getStream()` | Retrieve a stream representing the uploaded file. | |
+| `moveTo($targetPath)` | Move the uploaded file to a new location. | |
+| `getSize()` | Retrieve the file size. | |
+| `getError()` | Retrieve the error associated with the uploaded file. | |
+| `getClientFilename()` | Retrieve the filename sent by the client. | |
+| `getClientMediaType()` | Retrieve the media type sent by the client. | |
+
+> `RequestInterface`, `ServerRequestInterface`, `ResponseInterface` extend `MessageInterface`  because the `Request` and the `Response` are `HTTP Messages`.
+> When using `ServerRequestInterface`, both `RequestInterface` and `Psr\Http\Message\MessageInterface` methods are considered.
+

docs/PSR7-Usage.md

@@ -0,0 +1,168 @@
+### PSR-7 Usage
+
+All PSR-7 applications comply with these interfaces 
+They were created to establish a standard between middleware implementations.
+
+> `RequestInterface`, `ServerRequestInterface`, `ResponseInterface` extend `MessageInterface`  because the `Request` and the `Response` are `HTTP Messages`.
+> When using `ServerRequestInterface`, both `RequestInterface` and `Psr\Http\Message\MessageInterface` methods are considered.
+
+
+Enough with the talking, let's put things in practice.
+The following examples will illustrate how basic operations are done in PSR-7.
+
+#####Examples (using Zend Diactoros)
+
+Zend Diactoros is an implementation for PSR-7 interfaces. It will be used to illustrate these examples.
+Installation guide for Zend Diactoros: [Zend Diactoros Documentation - Installation](https://zendframework.github.io/zend-diactoros/install/)
+
+> All other PSR-7 implementations should have the same behaviour.
+
+To use the `Zend Diactoros` classes add this at the beggining of the php file:
+```php
+<?php
+
+// autoloading
+
+use Zend\Diactoros\ServerRequestFactory;
+use Zend\Diactoros\Response;
+
+$request = ServerRequestFactory::fromGlobals($_SERVER, $_GET, $_POST, $_COOKIE, $_FILES);
+$response = new Response();
+```
+
+### Working with HTTP Headers
+
+#### Adding headers to response:
+
+```php
+$response->withHeader('My-Custom-Header', 'My Custom Message');
+```
+
+#### Appending values to headers
+
+```php
+$response->withAddedHeader('My-Custom-Header', 'The second message');
+```
+
+#### Checking if header exists:
+
+```php
+$request->hasHeader('My-Custom-Header'); // will return false
+$response->hasHeader('My-Custom-Header'); // will return true
+```
+
+> Note: My-Custom-Header was only added in the Response
+
+#### Getting comma-separated values from a header (also applies to request)
+
+```php
+// getting value from request headers
+$request->getHeaderLine('Content-Type'); // will return: "text/html; charset=UTF-8"
+// getting value from response headers
+$response->getHeaderLine('My-Custom-Header'); // will return:  "My Custom Message; The second message"
+```
+
+#### Getting array of value from a header (also applies to request)
+```php
+// getting value from request headers
+$request->getHeader('Content-Type'); // will return: ["text/html", "charset=UTF-8"]
+// getting value from response headers
+$response->getHeader('My-Custom-Header'); // will return:  ["My Custom Message",  "The second message"]
+```
+
+#### Removing headers from HTTP Messages
+```php
+// removing a header from Request, removing deprecated "Content-MD5" header
+$request->withoutHeader('Content-MD5'); 
+
+// removing a header from Response
+// effect: the browser won't know the size of the stream
+// the browser will download the stream till it ends
+$response->withoutHeader('Content-Length');
+```
+
+### Working with HTTP Message Body
+
+When working with the PSR-7 there are two methods of implementation:
+#### 1. Getting the body separately
+
+> This method makes the body handling easier to understand and is useful when repeatedly calling body methods. (You only call `getBody()` once). Using this method mistakes like `$response->write()` are also prevented.
+
+```php
+$body = $response->getBody();
+// operations on body, eg. read, write, seek
+// ...
+// replacing the old body
+$response->withBody($body); 
+// this last statement is optional as we working with objects
+// in this case the "new" body is same with the "old" one
+// the $body variable has the same value as the one in $request, only the reference is passed
+```
+
+#### 2. Working directly on response
+
+> This method is useful when only performing few operations as the `$request->getBody()` statement fragment is required
+
+```php
+$response->getBody()->write('hello');
+```
+
+### Getting the body contents
+
+The following snippet gets the contents of a stream contents.
+> Note: Streams must be rewinded, if content was written into streams, it will be ignored when calling `getContents()` because the stream pointer is set to the last character, which is `\0` - meaning end of stream.
+```php 
+$body = $response->getBody();
+$body->rewind(); // or $body->seek(0);
+$bodyText = $body->getContends();
+```
+> Note: If `$body->seek(1)` is called before `$body->getContents()`, the first character will be ommited as the starting pointer is set to `1`, not `0`. This is why using `$body->rewind()` is recommended.
+
+### Append to body
+
+```php
+$response->getBody()->write('Hello'); // writing directly
+$body = $request->getBody(); // which is a `StreamInterface`
+$body->write('xxxxx');
+```
+
+### Prepend to body
+Prepending is different when it comes to streams. The content must be copied before writing the content to be prepended.
+The following example will explain the behaviour of streams.
+
+```php
+// assuming our response is initially empty
+$body = $repsonse->getBody();
+// writing the string "abcd"
+$body->write('abcd');
+
+// seeking to start of stream
+$body->seek(0);
+// writing 'ef'
+$body->write('ef'); // at this point the stream contains "efcd"
+```
+
+#### Prepending by rewriting separately
+
+```php
+// assuming our response body stream only contains: "abcd"
+$body = $response->getBody();
+$body->rewind();
+$contents = $body->getContents(); // abcd
+// seeking the stream to beginning
+$body->rewind();
+$body->write('ef'); // stream contains "efcd"
+$body->write($contents); // stream contains "efabcd"
+```
+
+> Note: `getContents()` seeks the stream while reading it, therefore if the second `rewind()` method call was not present the stream would have resulted in `abcdefabcd` because the `write()` method appends to stream if not preceeded by `rewind()` or `seek(0)`.
+
+#### Prepending by using contents as a string
+```php
+$body = $response->getBody();
+$body->rewind();
+$contents = $body->getContents(); // efabcd
+$contents = 'ef'.$contents;
+$body->rewind();
+$body->write($contents)
+```