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: * Web application
  * Database
  * Streaming platform
  
               ++++++++++++++++++++++++++++++     REST      +++++++++++++++++++++++++++++++++
               +                            +-------------->+ Service discovery - ZooKeeper +<----------+----------+
               +                            +               +++++++++++++++++++++++++++++++++           |          |
               + Streaming Platform - KAFKA +                                                           |          |
               +                            +                                                           |          |
               +                            +                                                           |          |
               ++++++++++++++++++++++++++++++                                                           |          |
                  + API +                  |                                                            |          |
                  +++++++                  | CONSUMER API                                               |          |
                     ^                     v                                                            |          |
                     | REST             +++++++++++++++++++++++++++++    DB DRIVER    ++++++++++++++++++++++++     |
                     |                  +        Broadcaster        +---------------->+                      +     |
                     |                  +       Reactivity API      +                 + Couchbase - Database +     |
                     |                  +         Spring Boot       +                 +                      +     |
                     |                  +++++++++++++++++++++++++++++                 ++++++++++++++++++++++++     |
                     |                         |        |                                                          |
                 +++++++++++++++        SSE    |        +----------------------------------------------------------+
                 + WebApp - JS +<--------------+
                 +++++++++++++++
  
  === Service discovery
  
  `ZooKeeper` is used as a centralized system to resolve all microservices.
  
negative.code: `Couchbase` is document oriented database and distributed by design that meets the scalability requirements of `Reactivity`.
  This database also provides additional interesting products like embedded database for mobile that can be leveraged to cover new features.
  This is why our primary choice goes for `Couchbase` server to store the data of `Reactivity`.
  
  Since a `JSON` document data model can be easily extended by addibg more properties to it, `Couchbase` also offers the opportunity to dynamically add extensions to `Reactivity`.
  
  == Components architecture view
  
  