Real Time REST API with WordPress

The release of WordPress 4.7 gave REST API endpoints to 27% of internet. Now the data (posts, comments, taxonomies, terms, users, options, etc.) from within your CMS is available for interaction. In order to get data from your site you have to send a request. The burden is on your API client to pester your API server with requests to ensure they have up to date data.
We live in a crazy mixed-up world with bots, microservices, and IoT. Polling the same API endpoint to see if something changed is taxing and inefficient. There is a better way with Webhooks.
Learn how subscription endpoints are the key to a real-time REST API. Notify a client that a new post published. Post a message to a Slack channel when a new comment is awaiting moderation. Receive a text message when a user resets their password. The use-cases are endless.

Transcript

1. REAL TIME
   REST APIS
   by: Rachel Baker
   

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2. REST API
   ENDPOINTS
   Baked into WordPress 4.7+
   

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3. GET https://demo.wp-api.org/wp-json/wp/v2/posts
   REVOLUTIONARY
   

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4. REST APIs REQUIRE
   CLIENTS TO MAKE
   REQUESTS
   How can your client know if the response
   data changed?
   

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5. SOMETIMES YOU NEED
   A LITTLE PUSH
   • Updating headless front-end application views for content changes
   (breaking news, new comment added, etc.)
   • Notifying a client or micro service application of a content event
   (comment awaiting moderation, post updated, new order received, etc.)
   • Attempting to keep anything in “sync” between WordPress and another
   application (users, newsletter subscribers, etc.)
   • Breaking cache or reseting cache headers
   

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6. WEBHOOKS
   +
   WORDPRESS ACTIONS
   =
   

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7. WEBHOOKS
   A WebHook is an HTTP callback: an HTTP POST
   that occurs when something happens; a simple
   event-notification via HTTP POST. A web
   application implementing WebHooks will POST a
   message to a URL when certain things happen.
   via https://webhooks.pbworks.com/w/page/13385124/FrontPage
   

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8. WORDPRESS ACTIONS
   In WordPress; an Action is a PHP function that is executed
   at specific points throughout the WordPress Core.
   Developers can create a custom Action using the Action API
   to add or remove code from an existing Action by specifying
   any existing Hook. This process is called "hooking".
   via https://codex.wordpress.org/Glossary#Action
   

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9. function notify_user_registered( $user_id ) {
   // authentication handling not shown.
   $request = new WP_REST_Request( 'GET', '/wp/v2/users/' . $user_id );
   $response = rest_do_request( $request );
   $status = $response->get_status();
   // $status should equal 200.
   $data = $response->get_data();
   $callback_uri = 'https://example.com/myclient/callback/
   user.registered';
   wp_safe_remote_post( $callback_uri, array( 'body' => $data ) );
   // check for errors.
   }
   add_action( 'user_register', 'notify_user_registered' );
   Notify a callback uri when a
   
   new user is created
   

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10. + REST HOOKS
    =
    

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11. REST HOOKS
    REST Hooks itself is not a specification, it is a
    collection of patterns that treat webhooks like
    subscriptions. These subscriptions are manipulated
    via a REST API just like any other resource.
    via http://resthooks.org/docs/
    

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12. WHAT YOU NEED
    1. Mechanism to store subscriptions

    2. Mechanism to list, create, modify, delete
    subscriptions via API endpoints

    3. List event hooks via API endpoint

    4. Mechanism to send hooks
    
    endpoints and authentication
    
    actions to send template response data to
    
    subscription uris
    

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13. SAMPLE HOOKS
    MODEL
    

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14. GET /wp-json/api/v1/hooks
    LIST HOOKS
    

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15. SAMPLE SUBSCRIPTION
    MODEL
    

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16. GET /wp-json/api/v1/subscriptions
    STORE & MODIFY
    SUBSCRIPTIONS
    POST /wp-json/api/v1/subscriptions
    GET /wp-json/api/v1/subscriptions/
    PUT /wp-json/api/v1/subscriptions/
    DELETE /wp-json/api/v1/subscriptions/
    

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17. GET /wp-json/api/v1/subscriptions
    LIST YOUR SUBSCRIPTIONS
    

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18. function notify_user_registered( $user_id ) {
    // authentication handling not shown.
    $request = new WP_REST_Request( 'GET', '/wp/v2/users/' . $user_id );
    $response = rest_do_request( $request );
    $status = $response->get_status();
    if ( 200 === $status ) {
    $data = $response->get_data();
    $subscriptions = get_available_subscriptions();
    foreach( $subscriptions as $subscription ) {
    if ( empty( $subscription['hook'] ) || 'user.created' !== $subscription['hook'] ) {
    continue;
    }
    wp_safe_remote_post( $subscription['uri'], array( 'body' => $data
    ) );
    // check for errors.
    }
    return;
    }
    }
    add_action( 'user_register', 'notify_user_registered' );
    Send response data to subscribers
    
    when a new user is created
    

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19. GOTCHAS
    • Error handling and optionally retrying connections for 4xx/5xx errors.

    • Performance of inline hook delivery. Consider a delayed queue system.

    • Impact of payload size. Consider reducing hook templates where possible.

    • Security and authentication.

    • You now have your own RPC API to maintain alongside your REST API.
    

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20. ICON CREDITS
    Pull by Venkatesh A.G.E
    Prodding by Luis Prado
    Hook by Alex Fuller
    Cake by Edward Boatman
    Valentine cake by Dinosoft Labs
    Newspaper by Noe Araujo
    Facepalm by Edward Boatman
    

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21. THANK YOU
    Rachel Baker
    @rachelbaker
    Slides are available at:
    
    https://speakerdeck.com/rachelbaker/real-time-rest-api-with-wordpress
    
    

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