anchor.diff:  * `flatMap` transforms the `Observable<HttpClientResponse>` -> `Observable<Buffer>`
   * `reduce` merge all response buffers in a single buffer
   * `map` transform the buffer to a string
  -* subscribe delivers the response content
  +* `subscribe` delivers the response content
   
   link:src/main/java/io/vertx/example/rx/http/reduce/Client.java[RxJava reduce HTTP client]
   
   === Zip
   
   A variation of the _simple_ example with two client requests mapped to an `Observable<JsonObject>`
  - and then zipped in a single json object.
  + and then _zipped_ in a single json object.
   
   The main interest is to get the final result when the two responses are delivered.
   
  -link:src/main/java/io/vertx/example/rx/http/zip/Client.java[Java zip HTTP client]
  +link:src/main/java/io/vertx/example/rx/http/zip/Client.java[RxJava zip HTTP client]
   
   === Unmarshalling
   
  
positive.code: The example Sender sends two messages over the event bus and wait for replies, the
  _zip_ operation is applied to deliver a single reply when the two replies are received.
  
  == RxJava Database examples
  
  === Jdbc example
  
  An example showing the Jdbc Service rxified api, after the client connected to the database, it chains
  operations via the `flatMap` operation and then subscribes to the result.
  
  link:src/main/java/io/vertx/example/rx/database/jdbc/Client.java[RxJava jdbc client]
  
negative.code: 
  A simple http server and client.
  
  The server uses an `Observable<HttpServerRequest>` to serve request:
  
  link:src/main/java/io/vertx/example/rx/http/simple/Server.java[RxJava simple HTTP server]
  
  The client uses an `Observable<HttpClientRequest` and applies `flatMap` to get a `Observable<Buffer>`
  
  