Please note that this project is still in the process of being prepared and polished to become a standalone tool and project. Any documentation might be incomplete and/or misleading. So no complains, you've been warned ;-) ..

OpenDataLayer

The Open Data Layer (ODL) is a concept designed to standardize common data communication between the frontend space (i.e. a website's frontend markup) and any third parties (e.g. analytics or affiliate tools). It's ultimate goal is to make third-party integration on websites less painful and more standardized while keeping the developers in full control of their frontend code.

The system has been developed for the online shop of Galeria Kaufhof, the leading german warehouse company and part of the HBC group, and is in use for almost three years now. And, since we are all convinced that this is a good approach, we decided to open-source it.

It is important to note that ODL is no tag manager in a classical way. However, it can (and should) be used as a replacement for external tag management systems.

• General concept
• Implementation
• Usage
• Plugins
• Events
• Models

---

General concept

Usually you would expect a Quickstart section at this point. Instead, we first describe the basic concept of the ODL before moving to Usage and Implementation details. It is really helpful to first get the big picture and understand the problems that are addressed by the ODL approach.

What is the problem?

You probably ask: What is the problem with common tag managagement systems? Any third-party vendor recommends me to use one and I don't have to care for all that marketing stuff myself. I really don't care about that type of thing.

Short answer

Unless you manage the tags yourself, you - the developer - are completely overruled when it comes to code execution within the client space of your website. If you manage the tags then you have application code split up into some 3rd party GUI somewhere on an external server.

Long answer

It highly depends on the size of your team and business. If you have a website that is run by three people, including developers, then you might be well-suited with an external tag management system (even though ODL would still be the best option, if used as a base for the 3rd party tagmanager). But starting with a medium-sized business and a dedicated online marketing department you might end up in a common situation: marketing asks for adding yet another "pixel" for the next best marketing tool and some junior dev (or even a marketeer himself, with support from an external agency) adds it to the tagmanager. Welcome to hell. You, the developer, are completely overruled when it comes to code execution within the client space of your website.

If you combine this with modern onsite marketing and A/B testing tools, you simply don't matter any more.

How does ODL fit in there?

...

How does ODL work?

The backend applications then render specific markup that gets analyzed and aggregated by the ODL. External plugins (econda, tag managers, affiliates, ..) can be integrated using a modularized architecture and can then access the data in the ODL.

The idea as such is quite common for tag managagement systems but any vendor uses his/her own implementation, based on more or less flexible data models.

TODO: more details here, maybe some pics

---

Implementation

TODO: Describe general flow of data, events etc.

Pass data to the ODL

The default way of passing data to the ODL is completely free of scripting and happens right from within a website's markup. You provide special <meta>-tags with the name attribute set to odl:data. The content attribute then contains a JSON-formatted object with any information to be supplied, based on the defined ODL model.

As a minimum requirement each page has to define a metatag with an ODLGlobalData](https://github.com/ryx/opendatalayer-model-default/model/ODLGlobalData.avdl) object, as illustrated in the following example:

<meta name="odl:data" content='{
  "site":{
    "id":"dev"
  },
  "page":{
    "type":"homepage",
    "name":"Startseite"
  },
  "user":{
    "id":"1234-5555-12-abcde"
  }
}' />

Pass events to the ODL

Passing events works in the same way as passing data.

TODO ...

Disabling the ODL within tests

You might want to disable the ODL on a page level, e.g. within the context of UATs or testing in general. You can use the following metatag for that, which completely stops the initialization of the ODL:

<meta name="odl:disable" content="true" />

---

Usage

The following steps should give a brief and easy-to-understand summary of the integration of ODL into your website. More detailed topics are covered in the other parts of the documentation. In almost any project you will completely abstract and automize the following steps inside your frontend build pipeline. The main reason to change the configuration after the inital setup is when you add or remove plugins.

1. Install the module

The easiest way to get started is by installing the ODL package, the ODL Builder and any plugins you need via npm:

npm install opendatalayer opendatalayer-builder opendatalayer-plugin-google-analytics --save-dev

2. Configure and build the ODL script

ODL comes with its own build tool called ODL Builder. You can use it to create your personallized ODL build by passing in your individual configuration (read more about the plugin configuration and ODL builder options in the respective sections). In most cases you would include the following code somewhere within your application's build process (e.g. gruntfile or gulpfile):

var odlBuilder = require('opendatalayer-builder');
 
odlBuilder.bundle({
  outputPath: 'build',
  outputFilename: 'my-odl-bundle.js',
  plugins: {
    'opendatalayer-plugin-google-analytics': {
      config: {
        id: 'UA-123456-foo',
        anonymizeIp: true,
      },
      rule: true,
    },
  },
});

As you can see ODL relies entirely on compile-time configuration to keep developers in full control over things happening in the client space. We at Galeria Kaufhof strongly believe in test-driven workflows and developer involvement. That's one reason we moved away from marketing-controlled tag management systems - and dont't regret it. However, it is still possible to dynamically load plugins through ODL's script API. That means one could even build a classical, UI-driven tag management system on top of the ODL standard.

3. Include ODL in your website

You can simply include ODL via an asynchronous script tag and then immediately access the API using the method queue pattern. Though, under normal circumstances there should be no need to directly access the ODL via the script API, unless you have some very special requirements. ODL is designed to be completely accessible through data-odl-* attributes (as described in detail in the Events documentation). Also the call to odl.initialize is intentionally left out here. When using ODL Builder the ODL is automatically configured and initialized behind the scenes.

<script src="/some/path/to/my-odl-bundle.js" type="text/javascript" async></script>
<script>
(function() {
  window._odlq = window._odlq || [];
  window._odlq.push(['broadcast', 'my-event', { foo: 'bar' }]);
}());
</script> 

4. Access the OpenDataLayer API at runtime

If you use an AMD-loader (like e.g. requirejs) you can easily import the module using asynchronous module definition syntax. Then you can directly access the API via the module's exported methods:

require(['/some/path/to/mywebsite-odl.1.123.js'], function (odl) {
  odl.broadcast('foo', 'bar');
});

All API methods are available either through the AMD module or the global window._odlq method queue (more details about the method queue pattern). In case of the window global you simply define an array with the function name followed by the function parameters. Then you push it to the global array. By extending the push method, ODL will execute the function as soon as it becomes available. The following two calls will have the same effect:

// method-queue-style API
window._odlq.push(['broadcast', 'my-event', { foo: 'bar' }]);
 
// AMD-style API
require(['opendatalayer'], function (odl) {
  odl.broadcast('my-event', { foo: 'bar' });
})

---

Plugins

The ODL provides a modular architecture where any additional logic is encapsulated in plugins. Plugins can access the global data aggregated by the ODL and also send and - more importantly - receive events.

ODL data flow

Whenever the ODL receives an event to be broadcasted it adds it to the internal queue and sends it to all currently loaded plugins. When a plugin is newly loaded it will receive all events that happened until that point - this has been a very clear design decision. We want to avoid situations where plugins are loaded late (e.g. through asynchronous loading) and then miss important information that happended earlier in the page's lifecycle.

Plugin configuration

TODO ...

Overriding plugin configurations on page-level

The ODL offers the possibility to provide dedicated configurations to plugins on a by-page-basis. This might be used to e.g. override URLs of a third-party system within integration tests. To achieve that you would simply define an odl:config-metatag, that can be used to override configuration within a plugin. Of course, the plugin has to actively support configuration overrides for this to work.

Example for overriding a plugin configuration from within the markup

<meta name="odl:config" content='{
  "odl/plugins/richrelevance":{
    "baseUrl": "mymockupserver",
    "forceDevMode": true
  }
}' />

---

Events

The ODL provides two different types of events: rendertime and runtime events. Using these events the ODL can receive data from either the page's markup or, asynchronously, from a script during the runtime of the page.

Rendertime Events

The rendertime events provide data for the ODL via a metatag that is already available when the page is delivered from the backend application. This data gets then aggregated by the ODL and is passed to the plugin's ìnitialize method.

Sending a global "pageload" event for a search result page

<meta name="odl:event" content='{
  "pageload": {
    "site":{
      "id":"dev"
    },
    "page":{
      "type":"search-result",
      "name":"Search Results"
    },
    "user":{
      "id":"1234-5555-12-abcde"
    }
  }
}' />

Supplying a 404 error using ODLErrorData

<meta name="odl:data" content='{
  "error": {
    "type": "404",
    "source": "/url/where/error/occured?foo=bar",
    "message": ""
  }
}' />

Runtime Events

In addition to the rendertime events the ODL provides runtime events which get broadcasted during runtime (e.g. z.B. Teaser-Click, Teaser-View, AddToCart, ...). These events are dispatched using a dedicated clientside API, based on Javascript. The following examples illustrate the different possibilities when using the client-side API.

Broadcasting the click on a teaser

The following snippet might be executed when the user clicks a teaser. It broadcasts a "teaser-click" event thorugh the ODL, directly passing the teaser id as event data. The event is then dispatched to all loaded plugins, which can react in any way (e.g. by sending the info to a third-party tracking tool of choice).

require(['odl/ODL'], (odl) {
  odl.broadcast({
    name: 'teaser-click',
    data: $teaserElement.attr('data-teaser-id'),
  });
});

Broadcasting an "addtocart" event with additional product data

The following code sends a "product-addtocart" event to the ODL and passes a (ODLCartProductData) as event data. Interested plugins could e.g. take this data and hand them over to affiliate pixels which then use it to optimize their conversion rate.

require(['odl/ODL'], (odl) {
  odl.broadcast({
    name: 'product-addtocart',
    data:
      id: '12344321',
      aonr: '123456789',
      ean: '41294791274912',
      name: 'Bunte Hose',
      quantity: 1,
      price: 29.95,
      vat: 4.23,
      discount: 4.94,
  });
});

Simplified markup notation

To remove the need of creating a dedicated script controller for any single event one might want to broadcast, the ODL offers a simpler, attribute-based way of broadcasting events. Using the data-odl-event-* attributes you can directly connect HTML elements to ODL events, without using Javascript. The following examples illustrate this feature:

Broadcasting the click on a teaser

<button data-odl-event-click='{"name": "newsletter-subscribe", "data": {"location": "homepage"}}'>
  Subscribe to our newsletter
</button>

Broadcasting the appearance of an element in the viewport

<div data-odl-event-view='{"name": "teaser-view", "data": {"location": "homepage"}}'>
  ...
</div>

Recommendation tracking

TODO ...

Media tracking

The media tracking through the ODL is based on a dedicated data type ODLMediaData. This data is supplied only during runtime, through the mediaplayer's script API. The ODL then automatically initializes the required tracking functionality (e.g. econda, rumba, ..), completely transparent for the user of the mediatracking API.

The communication between embedded player and ODL is done via runtime events, too. The player implementation has to handle various player events and then the according ODL events in return.

Event name	Data	Event
media-init	ODLMediaData	player initialization complete ("ready" event), passes info object with media data
media-played-25	ODLMediaPositionData	media has been played 25% from the beginning
media-played-50	ODLMediaPositionData	media has been played 50% from the beginning
media-played-75	ODLMediaPositionData	media has been played 75% from the beginning
media-played-95	ODLMediaPositionData	media has been played from the beginning "to the end", this is also given when not exactly 100% have been played (95% at least)

Sending a media-init event to the ODL (e.g. triggered when embedded player is ready)

odl.broadcast('media-init', {
  type: 'video',
  id: '20151212_Video_Startseite_Weihnachtsfilm',
  url: 'http://youtube.de/meinVideoShortcode',
  duration: 240
});

Sending a media-played-75 event to the ODL (for a previously initialized video with given ID)

odl.broadcast('media-played-75', {
  id: '20151212_Video_Startseite_Weihnachtsfilm',
  position: 180
});

---

Models

What is a "model" in the context of the ODL?

A model represents the structural "glue" between the ODL and the embedding website or webapplication. Each model provides type definitions used for passing data to the ODL. Additionally, it contains a JSON-based mapping that describes the data that has to be provided per pagetype.

A website that implements the ODL has to obey one specific model (either the default or any custom one) so the ODL and its tools (e.g. Builder and Validator) know where to expect which kind of data. Think of the model as a contract between a website and the ODL.

The default model is designed for e-commerce-driven websites (as ODL is originally built and developed within an e-commerce website) and contains a lot of product- and order-specific types. However, due to the modular concept it is easily possible to use ODL for any other website by simply using another model.

What are "types"?

Because of the non-statically-typed nature of Javascript and JSON the ODL implements several virtual data types used as a "contract" between any embedding applications and the ODL. The contained information is based on context (e.g. page, user, search, ...) and not on any business domain. The ODL datamodel is described using the AVRO description language, this allows for machine processing and automation of validation processes. The full list of type definitions is located in the respective model's repository.

---

Roadmap

Road to 1.0

• revive functional tests which broke by separating opendatalayer-builder
• cleanup data model: strip deprecated fields, remove inheritance
• fix logger issue (global flag from gk.toggle missing in ODL)
• move remaining datatypes to Avro model files
• Refactor ODL core implementation to a Promise-driven approach
• Support dynamic bundling in ODL builder to split the package into smaller files (e.g. one global file, one for article detail page, one for order completion page) to save ressources

Future plans

• Create a crawler tool that scans an entire website's markup and validates the included ODL metatags against the associated Avro model files
• Provide a gulp-opendatalayer plugin (may be obsolete due to Promise-driven odlBuilder.bundle())
• Provide a grunt-opendatalayer plugin
• Currently ODL is heavily focused on e-commerce websites, we should add more universal types to support more content-driven websites, as we have some more real use cases and/or feedback
• Add integrated testing tool that automatically tests plugins for availability based on their configuration
• Assign auto-generated IDs to plugins and generate a proxy-configuration together with the ODL. That could be used to enable reverse-proxy-based URL cloaking to stop most adblockers from working.