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Marc Moreram:
EventListeners as Collectors in Symfony
Aug 28, 2015 @ 08:25:07

Marc Moreram has posted a guide on his site to using event listeners as collectors in Symfony 2 based applications. He shows how to hook into the eventing system and both gather events fired (matching your criteria) and view the current collection.

Some of my concerns during the last couple of years have been how to collect data from all installed bundles using available tools in Symfony packages. I say concerns because I don’t really know if is there a tool for that. Some people have told me that the EventDispatcher component can do this work greatly, but then I have the same question once and again… is this component designed for such?

He uses an example of gathering mmoreram.wake_up events from his codebase, triggered when it "wakes up". He shows how to create a simple class for the event with a "rested" value. He modifies this to set up an array of "feelings" inside the event and a method to add new instances to the internal array. Finally he shows how to dispatch an event of the mmoreram.wake_up type and access the resulting set of "feelings" directly from the event.

tagged: event listener collector symfony feelings fire wakeup tutorial

Link: http://mmoreram.com/blog/2015/08/28/eventlisteners-as-collectors-in-symfony/

Marc Morera:
Re-thinking Event Listeners
Aug 21, 2015 @ 09:17:34

Marc Morera has posted an interesting article to his site suggesting a re-thinking of how event listeners are used in applications and libraries.

Let’s talk about Event Listeners. Do you know what an Event Listener is? Well, if you are used to working with Symfony, then you should know what is intended for. If you don’t, don’t hesitate to take a look at the Symfony documentation. This post aims to start a small discussion about how an Event Listener should look like if we really want to keep things decoupled.

The starts with a brief summary of the post (tl;dr) for those in a hurry but goes on to explain things in a bit more detail too. He starts by laying a foundation, introducing what event listeners are. He also shows how they're commonly implemented and used (in Symfony2 specifically but it applies more generally too) to trigger actions in applications. He suggests decoupling things a bit more from the flow of the action and allowing, in this case, access to both the order and the customer (on a "order created" action). He takes it one step further and decouples the sending of an email into a service and then creates an instance of this when needed in the event and not before.

tagged: event listener decouple ecommerce email order action

Link: http://mmoreram.com/blog/2015/08/20/re-thinking-event-listeners

Matthias Noback:
Experimenting with Broadway
Jul 13, 2015 @ 08:40:57

Matthias Noback has posted about some of his experimentation with Broadway, a framework of testing helpers and structure to create CQRS/event sourced applications. CQRS is a design pattern (Command Query Responsibility Segregation) that essentially defines the use of a different method for reading data than for working with it (ex: updates or creates).

At the Dutch PHP Conference I attended a workshop by Beau Simensen and Willem-Jan Zijderveld. They showed us some examples of how to work with Broadway, a framework for event sourcing, with full Symfony integration, created by the smart people at Qandidate.

During my two weeks of funemployment, before starting my new job at Ibuildings, I decided to recreate one of my previous projects using Broadway. As it turns out, it's a great framework that's quite easy to use and is very powerful at the same time. Even though it's not a stable package (as in, it's still in the 0.x version range), I think it's safe to depend on it.

Matthias found that one of the main features of the models in Broadway is the serialization of them for storage, but wanted to reduce the amount of time to handle that...so he created this library. He also talks about something that several have pointed out as missing in the Broadway structure: how to use "sagas". He ends the post with an update on his own tool, SimpleBus, that handles eventing and via message busses, noting that it's not going anywhere but if you use Broadway, there's no reason to use SimpleBus too.

tagged: broadway event cqrs framework experiment simplebus library

Link: http://php-and-symfony.matthiasnoback.nl/2015/07/experimenting-with-broadway/

Cees-Jan Kiewiet:
AWS PHP SDK Asynchronously
Jun 30, 2015 @ 11:31:15

Cees-Jan Kiewiet has a new post today talking about some interesting trickery he was able to do with the AWS (Amazon Web Services) PHP SDK to allow requests to be made asynchronously.

Just got off the AWS SDK for PHP Office Hour hangout and it was great talking with both team members Jeremy and Michael. And one of the things we talked about was async access to the AWS services using the PHP SDK. The goal of this post is to get the AWS PHP SDK client working asynchronously.

He starts with brief instructions on getting the SDK installed (via Composer) along with a library of his own that brings in a few other dependencies. The ReactPHP event loop is what makes the asynchronous connections possible. He includes the code to create the new handler stack and how to use it to make the asynchronous calls. A demo screencast is also included in the post to illustrate the output from a simple set of requests.

tagged: aws amazon sdk asynchronous connection reactphp event loop tutorial

Link: http://blog.wyrihaximus.net/2015/06/aws-php-sdk-asynchronously/

SitePoint PHP Blog:
Exploring Github’s Public Events with PHP and Google BigQuery
Jun 15, 2015 @ 13:10:14

The SitePoint PHP blog has a new tutorial posted showing you how to explore GitHubs public events through the GitHub API and handled via the Google BigQuery infrastructure taking the burden off your own systems.

If you’ve been following along with my previous articles about Github’s API, you know that Github’s developers are doing their best to ease the pain of interacting with Github data. In this article, we’re going to take a look at the Github public events API and we will build a small demo along the way.

They start off with a brief introduction to both GiHub events (like pushes, merges, etc) and the BigQuery system and the problem it solves. They use a stock Laravel framework-based application (on a Homestead Improved VM) and add in the Google API credentials and a BigQueryServiceProvider using Google's own client to make the connection. They also set up a middleware authentication mechanism to redirect the user if they're not authenticated. They then move over to the BigQuery side and show how to use it's web-based console to perform queries and view results. They then translate this over to a simple "top ten" query, listing the top repositories ordered by number of forks. Building on this, they add in a simple form that allows the user to specify the language to search for (PHP, Javascript, etc) and outputs the results via a Blade template.

tagged: google bigquery github event api tutorial topten forks

Link: http://www.sitepoint.com/exploring-githubs-public-events-php-google-bigquery/

SitePoint PHP Blog:
Real-time Apps with Laravel 5.1 and Event Broadcasting
Jun 10, 2015 @ 11:53:38

SitePoint's PHP Blog has a new tutorial posted showing you how to use event broadcasting in Laravel 5 to perform actions based on events the application issues.

In Laravel 5.1, the framework includes functionality called broadcasting events that makes it easy to create real-time apps in PHP. With this new functionality, an app can publish events to various cloud-based real-time PubSub solutions, like Pusher, or to Redis.

They start you off installing their sample application inside of a Homestead Improved virtual machine. They show you how to use the non-realtime version of the application and how the other parts of the application do not update when changes are made. They then create the ItemCreated, ItemUpdated and ItemDeleted events and the related data provider needed to "boot" the events. From there they walk you through installing the Pusher PHP library, including the matching Javascript file and a bit of code to push events and receive them in other parts of your application.

tagged: tutorial laravel5 realtime application pusher event broadcasting

Link: http://www.sitepoint.com/real-time-apps-laravel-5-1-event-broadcasting/

Reddit.com:
I feel like events are an anti-pattern
May 06, 2015 @ 10:55:00

On the /r/php subreddit frm Reddit.com, phpdevster proposes an interesting opinion - that an event system, set up with a listener and defined events, has become more of an anti-pattern in its most common implementation.

If events are only meant to be additional functionality that ALWAYS ALWAY ALWAYS should happen after a primary action is taken, how often is code really that absolute? Why are events not implemented in more flexible ways by frameworks? - that is implementing some inversion of control which would allow callers to determine which listeners would be relevant to the given context.

He illustrates his point with an example user registration system that fires a "user-was-registered" event that, in turn, fires off a series of events via a listener. He points out a pretty large flaw, though. While the functionality involved in the event is decoupled (the event itself), the behaviors defined by that event are not. Comments on the post offer some different options and solutions to the same problem including:

  • Further decoupling of the eventing process
  • Using objects with settable properties rather than just event name strings
  • The idea of using an "event store" to handle decoupling rather than more immediate code-based solutions

Have some thoughts of your own on events and decoupling? Go over and share them too.

tagged: event antipattern designpattern reddit opinion comments

Link: http://www.reddit.com/r/PHP/comments/34zp6j/i_feel_like_events_are_an_antipattern/

Matt Stauffer:
Laravel 5.0 - Generating Missing Events
Jan 28, 2015 @ 11:53:39

In the next part of his series introducing the upcoming version of the Laravel framework Matt Stauffer has posted part 16, about generating missing events.

Sometimes it can seem like a lot of work to create an event, create its handler, and bind the two. Create a command, create its handler, bind the two. I've often wished for a workflow that handled the whole process together in one. The artisan commands for generating commands and events are a good start--they both create their own entity and (optionally) its handler. But you still can spend an hour writing the command and handler, and then waste another 15 minutes trying to figure out why it's not working, only to realize you never actually bound the two together.

The solution to this in Laravel 5 is the "event:generate" handling with the artisan command line tool. He includes a look at the event handlers directories and files before executing the command and what changes post-execution, including the sample code generated for the event.

tagged: generate missing event tutorial part16 series laravel5

Link: http://mattstauffer.co/blog/laravel-5.0-generating-missing-events

Mathias Noback:
Collecting events and the event dispatching command bus
Jan 13, 2015 @ 11:52:33

Mathias Noback has posted the next part of his command bus in PHP series today with a few suggestions about event handling and when it's a good idea to dispatch them.

It was quite a ride so far. We have seen commands, command buses, events and event buses. We distilled some more knowledge about them while formulating answers to some interesting questions from readers.

In this new post, his focus is on collecting the events that happen as a part of the command's execution. He uses his "UserSignedUp" event his his previous example and a "send welcome email" handler to show why it may not be the best idea to execute all events simultaneously. Instead, he recommends making use of event collections (a feature his SimpleBus library supports) to define "providers" that can collect the events that need to happen and delegate the execution of them one after the other. Example code is included all through the post of events, providers and commands that make use of this idea.

tagged: commandbus command collect event provider dispatch tutorial

Link: http://php-and-symfony.matthiasnoback.nl/2015/01/collecting-events-and-the-events-aware-command-bus/

SitePoint PHP Blog:
Drupal 8 Hooks and the Symfony Event Dispatcher
Oct 21, 2014 @ 13:14:53

The SitePoint PHP blog has a new tutorial posted today showing the interaction between Drupal 8 hooks and the Symfony dispatcher in the last part of their series showing how to build a custom Drupal 8 module.

With the incorporation of many Symfony components into Drupal in its 8th version, we are seeing a shift away from many Drupalisms towards more modern PHP architectural decisions. For example, the both loved and hated hook system is getting slowly replaced. Plugins and annotations are taking away much of the need for info hooks and the Symfony Event Dispatcher component is replacing some of the invoked hooks. Although they remain strong in Drupal 8, it’s very possible that with Drupal 9 (or maybe 10) hooks will be completely removed.

He starts off with a brief introduction to what the event dispatcher is and how it currently interacts with the Drupal 8 system. He uses a simple form example with two text fields and how to hook in the dispatcher to fire a "demo_form.save" event when the user submits the form. He ties this into a DemoEvent and sets up a simple subscriber. He ends the article with a look at using hooks to achieve the same kind of goal.

tagged: drupal8 tutorial hooks event dispatcher symfony component

Link: http://www.sitepoint.com/drupal-8-hooks-symfony-event-dispatcher/