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A rack server built upon vert.x, can be used as a vertx module

Jubilee / mod-rack

A rack server for jruby.

Also works as vertx module.

Get started

Please checkout the wiki page before you proceed.

Add the following snippet to $VERTX\_HOME/conf/


Make sure JRUBY_HOME is correctly set, and rack gem is install before proceed.

Then run the rackup file as a normal verticle,

vertx run

Build from source

First checkout the source from github.

  1. To run as a vertx module, run the following command in the root directory:

    mvn package
    vertx create-module-link org.jruby.jubilee~mod-rack~0.1.3-SNAPSHOT

    then change your file to point to the new module:

  2. To run as rubygem, run rake install in the root directory, maven is required.

Event Bus

Event Bus is a pub/sub mechanism, it can be used from server to server, server to client and client to client, with the same API! You can use it to build living real time web application.


Assume necessary javascript files are loaded in the page (they can be found here), run rack application with the following config:

$ cat config.json
{ "host": "",
  "port": 8080,
  "event_bus": "/eventbus"
$ vertx run -conf config.json

In one browser:

var eb = new vertx.EventBus("/eventbus");
eb.registerHandler("test", function(data){;

In another:

var eb = new vertx.EventBus("/eventbus");
eb.send("test", "hello, world");

In the previous tab it should print the greetings you just sent.

For more advanced examples, please checkout the chatapp.

EventBus Security

The EventBus can (and probably should) be secured by passing in parameters in the config.json object.

The following config will allow all messages from the browser to accounts.get_balances and only allow messages outward that match the format accounts.get_balances.*.

$ cat config.json
  "host": "",
  "port": 8080,
  "event_bus": "/eventbus",
      "incoming": [{address: "user_accounts.get_balances"}],
      "outgoing": [{address_re: "user_accounts.balances.*"}]

More details of parameters can be found in the VertX docs

By default the bridge is left wide open. Any browser connected to an application can observe all messages being passed on your EventBus.

Performance Tuning

If you're creating a lot of connections to a Jubilee(Vert.x) server in a short period of time, e.g. benchmarking with tools like wrk, you may need to tweak some settings in order to avoid the TCP accept queue getting full. This can result in connections being refused or packets being dropped during the handshake which can then cause the client to retry.

A classic symptom of this is if you see long connection times just over 3000ms at your client.

How to tune this is operating system specific but in Linux you need to increase a couple of settings in the TCP / Net config (10000 is an arbitrarily large number)

sudo sysctl -w net.core.somaxconn=10000
sudo sysctl -w net.ipv4.tcp_max_syn_backlog=10000

For other operating systems, please consult your operating system documentation.




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