Quickstart

This 10-minute guide will show you how to run an entire Hermes environment, create topic and subscription and publish some messages.

Prerequisities

In order to go through this tutorial you need to have:

Setting up an environment

As described in architecture section, Hermes consists of multiple modules and requires Kafka and Zookeeper to run. To make this easy, we prepared a Vagrant file.

git clone https://github.com/allegro/hermes.git
cd hermes
vagrant up

If you want to run specific version of Hermes, simply checkout a tag:

git checkout hermes-{version}

Checking the setup

If the system is running, you should see Hermes Console when visiting Vagrant public IP in the browser. Just head to http://10.10.10.10/.

Creating group and topic

Now you're ready to create a topic for publishing messages.

In Hermes messages are published on topics which are aggregated into groups. So, you'll need to create a group first, let's name it com.example.events.

  • head to Hermes Console
  • click the blue plus button
  • enter group name: com.example.events
  • all the other information is required, but just enter whatever for now

At this point, you should see your group on the group list. Now let's add new clicks topic to our group:

  • click the group header (direct link to com.example.events group)
  • click the blue plus button
  • enter topic name: clicks
  • enter some description
  • change content type to JSON - we don't want to add AVRO schema yet for the sake of simplicity

Publishing and receiving messages

To receive messages that are published on topic you have to create a subscription. This is where you tell Hermes where to send messages published on a topic. You can have many subscriptions on a single topic (in particular - none).

So let's create a clicks-receiver subscription:

  • click the topic header (direct link to com.example.events.clicks group)
  • click the blue plus button
  • enter subscription name: clicks-receiver
  • set the endpoint to which messages will be sent, in this example we can use http://requestb.in/1isy54g1
  • enter some description and contact data

Now it's time for a grand finale. Let's publish a message on our topic (note that default Hermes publishing port is 8080):

curl -v -d '{"id": 12345, "page": "main"}' http://10.10.10.10:8080/topics/com.example.events.clicks

< HTTP/1.1 201 Created
< Hermes-Message-Id: 66feaead-0685-491e-9c87-00f940ead2c9
< Content-Length: 0
< Date: Mon, 04 May 2015 02:18:23 GMT

(the first time you publish something you might see 408 Request Time-out status: a lot of machinery needs to warm up, just hit retry)

Congratulations! The message should be delivered to your service or visible via e.g. http://requestb.in/1isy54g1?inspect.

Stopping the system

To stop the virtual machine run:

vagrant halt

Run it again with:

vagrant up

Destroy the VM with:

vagrant destroy