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• How to expose new API methods in the HTTP Reporting API – Introducing the Piwik Platform

  26 février 2015, par Thomas Steur — Development

  This is the next post of our blog series where we introduce the capabilities of the Piwik platform (our previous post was How to write UI tests for your plugin). This time you’ll learn how to extend our Reporting API. For this tutorial you will need to have basic knowledge of PHP.

  What is Piwik’s Reporting API ?

  It allows third party applications to access analytics data and manipulate miscellaneous data (such as users or websites) through HTTP requests.

  What is it good for ?

  The Reporting API is used by the Piwik UI to render reports, to manage users, and more. If you want to add a feature to the Piwik UI, you might have to expose a method in the API to access this data. As the API is called via HTTP it allows you to fetch or manipulate any Piwik related data from anywhere. In these exposed API methods you can do pretty much anything you want, for example :

  • Enhance existing reports with additional data
  • Filter existing reports based on custom rules
  • Access the database and generate custom reports
  • Persist and read any data
  • Request server information

  Getting started

  In this series of posts, we assume that you have already set up your development environment. If not, visit the Piwik Developer Zone where you’ll find the tutorial Setting up Piwik.

  To summarize the things you have to do to get setup :

  • Install Piwik (for instance via git).
  • Activate the developer mode : ./console development:enable.
  • Generate a plugin : ./console generate:plugin --name="MyApiPlugin". There should now be a folder plugins/MyApiPlugin.
  • And activate the created plugin : ./console plugin:activate "MyApiPlugin"

  Let’s start creating an API

  We start by using the Piwik Console to create a new API :

  ./console generate:api

  The command will ask you to enter the name of the plugin the created API should belong to. I will simply use the above chosen plugin name “MyApiPlugin”. There should now be a file plugins/MyApiPlugin/API.php which contains already an example to get you started easily :

  class API extends \Piwik\Plugin\API
  {
      public function getAnswerToLife($truth = true)
      {
          if ($truth) {
              return 42;
          }
   
          return 24;
      }
   
      public function getExampleReport($idSite, $period, $date, $wonderful = false)
      {
          $table = DataTable::makeFromSimpleArray(array(
              array('label' => 'My Label 1', 'nb_visits' => '1'),
              array('label' => 'My Label 2', 'nb_visits' => '5'),
          ));
   
          return $table;
      }
  }
  Télécharger

  Any public method in that file will be available via the Reporting API. For example the method getAnswerToLife can be called via this URL : index.php?module=API&method=MyApiPlugin.getAnswerToLife. The URL parameter method is a combination of your plugin name and the method name within this class.

  Passing parameters to your method

  Both example methods define some parameters. To pass any value to a parameter of your method simply specify them by name in the URL. For example ...&method=MyApiPlugin.getExampleReport&idSite=1&period=week&date=today&wonderful=1 to pass values to the parameters of the method getExampleReport.

  Returning a value

  In an API method you can return any boolean, number, string or array value. A resource or an object cannot be returned unless it implements the DataTableInterface such as DataTable (the primary data structure used to store analytics data in Piwik), DataTable\Map (stores a set of DataTables) and DataTable\Simple (a DataTable where every row has two columns : label and value).

  Did you know ? You can choose the response format of your API request by appending a parameter &format=JSON|XML|CSV|... to the URL. Check out the Reporting API Reference for more information.

  Best practices

  Check user permissions

  Do not forget to check whether a user actually has permissions to access data or to perform an action. If you’re not familiar with Piwik’s permissions and how to check them read our User Permission guide.

  Keep API methods small

  At Piwik we aim to write clean code. Therefore, we recommend to keep API methods small (separation of concerns). An API pretty much acts like a Controller :

  public function createLdapUser($idSite, $login, $password)
  {
      Piwik::checkUserHasAdminAccess($idSite);
      $this->checkLogin($login);
      $this->checkPassword($password);
      
      $myModel = new LdapModel();
      $success = $myModel->createUser($idSite, $login, $password);
      
      return $success;
  }
  Télécharger

  This is not only easy to read, it will also allow you to create simple tests for LdapModel (without having to bootstrap the whole Piwik layer) and you will be able to reuse it in other places if needed.

  Calling APIs of other plugins

  For example if you want to fetch an existing report from another plugin, say a list of all Page URLs, do not request this report by calling that method directly :

  \Piwik\Plugins\Actions\API::getInstance()->getPageUrls($idSite, $period, $date);

  . Instead, issue a new API request :

  $report = \Piwik\API\Request::processRequest('Actions.getPageUrls', array(
  
      'idSite' => $idSite,
  
      'period' => $period,
  
      'date'   => $date,
  
  ));

  This has several advantages :

  • It avoids a fatal error if the requested plugin is not available on a Piwik installation
  • Other plugins can extend the called API method via events (adding additional report data to a report, doing additional permission checks) but those events will be only triggered when requesting the report as suggested
  • If the method parameters change, your request will most likely still work

  Publishing your Plugin on the Marketplace

  In case you want to share your API with other Piwik users you can do this by pushing your plugin to a public GitHub repository and creating a tag. Easy as that. Read more about how to distribute a plugin and best practices when publishing a plugin.

  Isn’t it easy to create a API ? We never even created a file ! If you have any feedback regarding our APIs or our guides in the Developer Zone feel free to send it to us.

• ffmpeg : 1 frame manipulation on demand

  7 juillet 2013, par Chris Russo

  Hello folks & friends of SO !

  We need to create a small application to take a random frame from a video, and apply some modifications to it, in real time.

  This has to be done in real time, and in order to do that, we wouldn't mind to create some initial delay, before the video starts streaming. So let's assume we have a total of 6 seconds of preloading time, in order to :

  1) extract a keyframe.
  
  2) create an image with it.
  
  3) manipulate the image.
  
  4) replace the original keyframe with the new one.

  The point (3) of the previous algorithm is already solved using GD as a PHP module. However we would need to find a solution for the rest of the procedure in order to accomplish this.

  Please if anyone is available to help us with this, feel free to contact me.

  Thanks in advance ;
  Chris C. Russo

• GStreamer x264enc not found

  5 avril 2017, par Dominik Schreiber

  I installed GStreamer-0.10 and all modules (base, good, bad, ugly, ffmpeg) according to these instructions (browse through by clicking prev/next) :
  http://www.linuxfromscratch.org/blfs/view/svn/multimedia/gst-plugins-ugly.html

  Everything seemed to have worked just fine but when I want to execute my pipeline I got this error :

  glib.GError: no element "x264enc"

  Apparently the module was not installed :

  gst-inspect x264enc
  
  No such element or plugin 'x264enc'

  After that I installed the codec by executing :

  sudo apt-get install x264

  This did not work either. So I installed the latest build manually :
  http://www.videolan.org/developers/x264.html

  After a successful installation of x264 I ran ./configure on the gstreamer-0.10 ugly modules once again and found out about this :

  configure: *** checking feature: x264 plug-in ***
  
  configure: *** for plug-ins: x264 ***
  
  checking for X264... no
  
  configure: No package 'x264' found
  
  configure: *** These plugins will not be built: x264
  
  configure: creating ./config.status

  A check if x264 is available seems to get fullfilled :

  which x264
  
  /usr/local/bin/x264

  I’m using ubuntu server 12.04 LTS. Any ideas what I have to do to compile this module properly ? Thanks !