<?xml version="1.0" encoding="UTF-8"?>
<!-- Reviewed: no -->
<sect2 id="zend.oauth.introduction.getting-started">
    <title>Getting Started</title>

    <para>
        With the OAuth protocol explained, let's show a simple example of it with
        source code. Our new Consumer will be handling Twitter Status submissions.
        To do so, it will need to be registered with Twitter in order to receive
        an OAuth Consumer Key and Consumer Secret. This are utilised to obtain
        an Access Token before we use the Twitter <acronym>API</acronym> to post a status message.
    </para>

    <para>
        Assuming we have obtained a key and secret, we can start the OAuth workflow
        by setting up a <classname>Zend_Oauth_Consumer</classname> instance as
        follows passing it a configuration (either an array or <classname>Zend_Config</classname>
        object).
    </para>

    <programlisting language="php"><![CDATA[
$config = array(
    'callbackUrl' => 'http://example.com/callback.php',
    'siteUrl' => 'http://twitter.com/oauth',
    'consumerKey' => 'gg3DsFTW9OU9eWPnbuPzQ',
    'consumerSecret' => 'tFB0fyWLSMf74lkEu9FTyoHXcazOWpbrAjTCCK48A'
);
$consumer = new Zend_Oauth_Consumer($config);
]]></programlisting>

    <para>
        The callbackUrl is the URI we want Twitter to request from our server
        when sending information. We'll look at this later. The siteUrl is the
        base URI of Twitter's OAuth <acronym>API</acronym> endpoints. The full list of endpoints
        include http://twitter.com/oauth/request_token, http://twitter.com/oauth/access_token,
        and http://twitter.com/oauth/authorize. The base siteUrl utilises a convention
        which maps to these three OAuth endpoints (as standard) for requesting a
        request token, access token or authorization. If the actual endpoints of
        any service differ from the standard set, these three URIs can be separately
        set using the methods <methodname>setRequestTokenUrl()</methodname>,
        <methodname>setAccessTokenUrl()</methodname>,
        and <methodname>setAuthorizeUrl()</methodname> or the configuration fields requestTokenUrl,
        accessTokenUrl and authorizeUrl.
    </para>

    <para>
        The consumerKey and consumerSecret are retrieved from Twitter when your
        application is registered for OAuth access. These also apply to any OAuth
        enabled service, so each one will provide a key and secret for your
        application.
    </para>

    <para>
        All of these configuration options may be set using method calls simply
        by converting from, e.g. callbackUrl to setCallbackUrl().
    </para>

    <para>
        In addition, you should note several other configuration values not
        explicitly used: requestMethod and requestScheme. By default,
        <classname>Zend_Oauth_Consumer</classname> sends requests as POST (except for a
        redirect which uses <constant>GET</constant>). The customised client (see later) also
        includes its authorization by way of a header. Some services may, at their discretion,
        require alternatives. You can reset the requestMethod (which defaults
        to Zend_Oauth::POST) to Zend_Oauth::GET, for example, and reset the
        requestScheme from its default of Zend_Oauth::REQUEST_SCHEME_HEADER to one
        of Zend_Oauth::REQUEST_SCHEME_POSTBODY or
        Zend_Oauth::REQUEST_SCHEME_QUERYSTRING. Typically the defaults should work
        fine apart from some exceptional cases. Please refer to the service provider's
        documentation for more details.
    </para>

    <para>
        The second area of customisation is how <acronym>HMAC</acronym> operates
        when calculating/comparing them for all requests. This is configured using
        the signatureMethod configuration field or <methodname>setSignatureMethod()
        </methodname>. By default this is HMAC-SHA1. You can set it also to a provider's
        preferred method including RSA-SHA1. For RSA-SHA1, you should also configure
        RSA private and public keys via the rsaPrivateKey and rsaPublicKey configuration
        fields or the <methodname>setRsaPrivateKey()</methodname> and
        <methodname>setRsaPublicKey()</methodname> methods.
    </para>

    <para>
        The first part of the OAuth workflow is obtaining a request token. This
        is accomplished using:
    </para>

    <programlisting language="php"><![CDATA[
$config = array(
    'callbackUrl' => 'http://example.com/callback.php',
    'siteUrl' => 'http://twitter.com/oauth',
    'consumerKey' => 'gg3DsFTW9OU9eWPnbuPzQ',
    'consumerSecret' => 'tFB0fyWLSMf74lkEu9FTyoHXcazOWpbrAjTCCK48A'
);
$consumer = new Zend_Oauth_Consumer($config);

// fetch a request token
$token = $consumer->getRequestToken();
]]></programlisting>

    <para>
        The new request token (an instance of <classname>Zend_Oauth_Token_Request
        </classname>) is unauthorized. In order to exchange it for an authorized
        token with which we can access the Twitter <acronym>API</acronym>, we need the user to
        authorize it. We accomplish this by redirecting the user to Twitter's authorize endpoint
        via:
    </para>

    <programlisting language="php"><![CDATA[
$config = array(
    'callbackUrl' => 'http://example.com/callback.php',
    'siteUrl' => 'http://twitter.com/oauth',
    'consumerKey' => 'gg3DsFTW9OU9eWPnbuPzQ',
    'consumerSecret' => 'tFB0fyWLSMf74lkEu9FTyoHXcazOWpbrAjTCCK48A'
);
$consumer = new Zend_Oauth_Consumer($config);

// fetch a request token
$token = $consumer->getRequestToken();

// persist the token to storage
$_SESSION['TWITTER_REQUEST_TOKEN'] = serialize($token);

// redirect the user
$consumer->redirect();
]]></programlisting>

    <para>
        The user will now be redirected to Twitter. They will be asked to authorize
        the request token attached to the redirect URI's query string. Assuming they
        agree, and complete the authorization, they will be again redirected, this
        time to our Callback URL as previously set (note that the callback URL is
        also registered with Twitter when we registered our application).
    </para>

    <para>
        Before redirecting the user, we should persist the request token to storage.
        For simplicity I'm just using the user's session, but you can easily use a
        database for the same purpose, so long as you tie the request token to the
        current user so it can be retrieved when they return to our application.
    </para>

    <para>
        The redirect URI from Twitter will contain an authorized Access Token. We
        can include code to parse out this access token as follows - this source
        code would exist within the executed code of our callback URI. Once parsed
        we can discard the previous request token, and instead persist the access
        token for future use with the Twitter <acronym>API</acronym>. Again, we're simply persisting
        to the user session, but in reality an access token can have a long lifetime
        so it should really be stored to a database.
    </para>

    <programlisting language="php"><![CDATA[
$config = array(
    'callbackUrl' => 'http://example.com/callback.php',
    'siteUrl' => 'http://twitter.com/oauth',
    'consumerKey' => 'gg3DsFTW9OU9eWPnbuPzQ',
    'consumerSecret' => 'tFB0fyWLSMf74lkEu9FTyoHXcazOWpbrAjTCCK48A'
);
$consumer = new Zend_Oauth_Consumer($config);

if (!empty($_GET) && isset($_SESSION['TWITTER_REQUEST_TOKEN'])) {
    $token = $consumer->getAccessToken(
                 $_GET,
                 unserialize($_SESSION['TWITTER_REQUEST_TOKEN'])
             );
    $_SESSION['TWITTER_ACCESS_TOKEN'] = serialize($token);

    // Now that we have an Access Token, we can discard the Request Token
    $_SESSION['TWITTER_REQUEST_TOKEN'] = null;
} else {
    // Mistaken request? Some malfeasant trying something?
    exit('Invalid callback request. Oops. Sorry.');
}
]]></programlisting>

    <para>
        Success! We have an authorized access token - so it's time to actually
        use the Twitter <acronym>API</acronym>. Since the access token must be included with every
        single <acronym>API</acronym> request, <classname>Zend_Oauth_Consumer</classname> offers a
        ready-to-go <acronym>HTTP</acronym> client (a subclass of
        <classname>Zend_Http_Client</classname>) to use either by itself or by passing it as a
        custom <acronym>HTTP</acronym> Client to another library or
        component. Here's an example of using it standalone. This can be done
        from anywhere in your application, so long as you can access the OAuth
        configuration and retrieve the final authorized access token.
    </para>

    <programlisting language="php"><![CDATA[
$config = array(
    'callbackUrl' => 'http://example.com/callback.php',
    'siteUrl' => 'http://twitter.com/oauth',
    'consumerKey' => 'gg3DsFTW9OU9eWPnbuPzQ',
    'consumerSecret' => 'tFB0fyWLSMf74lkEu9FTyoHXcazOWpbrAjTCCK48A'
);

$statusMessage = 'I\'m posting to Twitter using Zend_Oauth!';

$token = unserialize($_SESSION['TWITTER_ACCESS_TOKEN']);
$client = $token->getHttpClient($configuration);
$client->setUri('http://twitter.com/statuses/update.json');
$client->setMethod(Zend_Http_Client::POST);
$client->setParameterPost('status', $statusMessage);
$response = $client->request();

$data = Zend_Json::decode($response->getBody());
$result = $response->getBody();
if (isset($data->text)) {
    $result = 'true';
}
echo $result;
]]></programlisting>

    <para>
        As a note on the customised client, this can be passed to most
        Zend Framework service or other classes using <classname>Zend_Http_Client
        </classname> displacing the default client they would otherwise use.
    </para>
</sect2>
