anchor.diff:  ==== Web application
   
   The web application consumes `SSE` streams from the back-end.
  -It also pushes new messages to the `Kafka` service to be validated asynchronously by `Reactivity`.+It also pushes new messages to the `Kafka` service to be validated asynchronously by `Reactivity`.
  +
  +=== Extensions
  +
  +Extensions are playing the role of additional API.
  +Recommended technology for their implementation is `Spring Boot` but it's not mandatory.
  +However, an extension must follow the standards defined by `Reactivity` architecture:
  +
  +* A micro service that registers to `ZooKeeper`
  +* Consumes data through `Kafka` connectors
  +* Persist data to `Couchbase` and send notification through `Kafka`
  +
  +Additional statics (`JS`, `CSS`, `HTML`) can be also served to the web application in order to extend the user experience of `Reactivity`.
positive.code: In case of unexpected desynchronization (typically a state that is expected to be synchronized regarding the messages that are delivered and those who are not), a re-initialization of that data should be possible.
  Message streaming should be used as much as possible to replicate a data from scratch, including transformations process.
  
  == Key technologies
  
  === Based on OSS
  
negative.code: * Web application
  * Database
  * Streaming platform
  * Extensions
  
               ++++++++++++++++++++++++++++++     REST      +++++++++++++++++++++++++++++++++
               +                            +-------------->+ Service discovery - ZooKeeper +<----------+----------+
               +                            +               +++++++++++++++++++++++++++++++++      |    |          |
               + Streaming Platform - KAFKA +                                                      |    |          |
               +                            +      CONSUMER API     ++++++++++++++++++++           |    |          |
               +                            +<------------+---------+ Extension(s) ... +-----------+    |          |
               ++++++++++++++++++++++++++++++   REST      |         ++++++++++++++++++++                |          |
  			                     |  + API +<-------+    |              + STATICS +  |                 |          |
  			                     |  +++++++        |    |              +++++++++++  |                 |          |
  								 |                 |    |                  ^        |                 |          |
                                   |               ++++++++++++++++          |        |DB DRIVER        |          |
                                   |               +  WebApp - JS +----------+        +--------+        |          |
                                   |               ++++++++++++++++                            |        |          |
  				                 |                     ^                                     |        |          |
  				                 |                     | SSE                                 |        |          |
  				                 |                     |                                     v        |          |
                                   |    +++++++++++++++++++++++++++++    DB DRIVER    ++++++++++++++++++++++++     |
                                   +--->+        Broadcaster        +---------------->+                      +     |
                                        +       Reactivity API      +                 + Couchbase - Database +     |
                                        +         Spring Boot       +                 +                      +     |
                                        +++++++++++++++++++++++++++++                 ++++++++++++++++++++++++     |
                                                        |                                                          |
                                                        +----------------------------------------------------------+
               
  === Service discovery
  
  `ZooKeeper` is used as a centralized system to resolve all microservices.
  