Updated readme with usage

README.md

@@ -5,3 +5,137 @@
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+
+Async caching aware http client
+
+## Requirements
+
+- PHP 7.3
+- Redis (if wanting to use the Redis caching provider)
+
+In addition for non-blocking context one of the following event libraries should be installed:
+
+- [ev](https://pecl.php.net/package/ev)
+- [event](https://pecl.php.net/package/event)
+- [php-uv](https://github.com/bwoebi/php-uv)
+
+## Installation
+
+```
+composer require harmonyio/http-client
+```
+
+## Usage
+
+### Caching requests
+
+The following example shows how to make a request and cache the result so consecutive calls will used the cached results instead of making a new external HTTP call.
+
+```php
+<?php declare(strict_types=1);
+
+namespace Foo;
+
+use Amp\Artax\DefaultClient;
+use Amp\Redis\Client;
+use HarmonyIO\Cache\Provider\Redis;
+use HarmonyIO\Cache\Ttl;
+use HarmonyIO\HttpClient\Client\ArtaxClient;
+use HarmonyIO\HttpClient\Message\CachingRequest;
+use function Amp\wait;
+
+// create instance of the HTTP client
+$httpClient = new ArtaxClient(
+    new DefaultClient(),
+    new Redis(new Client('tcp://127.0.0.1:6379'))
+);
+
+// create a new request to be cached for 10 seconds
+$request = new CachingRequest('TestRequestKey', new Ttl(10), 'https://httpbin.org/get');
+
+// make the request and cache it
+$result = wait($httpClient->request($request));
+
+// all consecutive requests will now used the cached result instead of calling the external service again
+$result = wait($httpClient->request($request));
+```
+
+### Non-caching requests
+
+It is also possible to make non-caching requests.
+
+```php
+<?php declare(strict_types=1);
+
+namespace Foo;
+
+use Amp\Artax\DefaultClient;
+use Amp\Redis\Client;
+use HarmonyIO\Cache\Provider\Redis;
+use HarmonyIO\HttpClient\Client\ArtaxClient;
+use HarmonyIO\HttpClient\Message\Request;
+use function Amp\wait;
+
+// create instance of the HTTP client
+$httpClient = new ArtaxClient(
+    new DefaultClient(),
+    new Redis(new Client('tcp://127.0.0.1:6379'))
+);
+
+// create a new request to be cached for 10 seconds
+$request = new Request('https://httpbin.org/get');
+
+// make the request (the results will NOT be cache)
+$result = wait($httpClient->request($request));
+
+// make the same request again
+$result = wait($httpClient->request($request));
+```
+
+## Client interface
+
+The HTTP client's interface only contains a single method: `Client::request(\HarmonyIO\HttpClient\Message\Request $request)`.
+
+The `$request` parameter can be either a "normal" non-caching request (`HarmonyIO\HttpClient\Message\Request`) or a caching request (`HarmonyIO\HttpClient\Message\CachingRequest`).
+
+### `HarmonyIO\HttpClient\Message\Request`
+
+The constructor of the request class expects at least a URL to make the request to and optionally an HTTP method (defaults to GET).
+
+Optional request parts can be set in setter method of the request class:
+
+```php
+<?php declare(strict_types=1);
+
+namespace Foo;
+
+use HarmonyIO\HttpClient\Message\Request;
+
+$request = (new Request('https://httpbin.org/post', 'POST'))
+    ->setProtocolVersions('1.1', '2.0')
+    ->addHeader('foo', 'bar')
+    ->addHeader('baz', 'qux')
+    ->setBody('foobar')
+;
+```
+
+### `HarmonyIO\HttpClient\Message\CachingRequest`
+
+The constructor of the caching request class expects at least a key, a TTL, the URL to make the request to and optionally an HTTP method (defaults to GET).
+
+Optional request parts can be set in setter method of the request class as defined in the previous section.
+
+```php
+<?php declare(strict_types=1);
+
+namespace Foo;
+
+use HarmonyIO\Cache\Ttl;
+use HarmonyIO\HttpClient\Message\CachingRequest;
+
+$request = (new CachingRequest('UniqueCachingKey', new Ttl(Ttl::ONE_HOUR), 'https://httpbin.org/get'))
+    ->setProtocolVersions('1.1', '2.0')
+    ->addHeader('foo', 'bar')
+    ->addHeader('baz', 'qux')
+;
+```