ping-json

A simple ping-pong service implementation that that integrates ringpop to forward requests between nodes.

Note: this file can be cram-executed using make test-examples. That's why some of the example outputs below are a bit unusual.

Running the example

All commands are relative to this directory:

$ cd ${TESTDIR}  # examples/ping-json
$ go build

Start a custer of 5 nodes using tick-cluster:

$ tick-cluster.js --interface=127.0.0.1 -n 5 ping-json &> tick-cluster.log &
$ sleep 5

Lookup the node my_key key belongs to using tcurl:

$ tcurl ringpop -P hosts.json /admin/lookup '{"key": "my_key"}'
{"ok":true,"head":null,"body":{"dest":"127.0.0.1:300?"},"headers":{"as":"json"},"trace":"*"} (glob)

Call the /ping endpoint (multiple times) and see the request being forwarded. Each request is sent to a random node in the cluster because of the -P hosts.json argument--but is always handled by the node owning the key. This can be seen in the from field of the response:

$ tcurl pingchannel -P hosts.json /ping '{"key": "my_key"}'
{"ok":true,"head":null,"body":{"message":"Hello, world!","from":"127.0.0.1:300?","pheader":""},"headers":{"as":"json"},"trace":"*"} (glob)

Optionally, set the p header. This value will be forwarded together with the request body to the node owning the key. Its value is returned in the response body in the pheader field:

$ tcurl pingchannel -P hosts.json /ping '{"key": "my_key"}' --headers '{"p": "my_header"}'
{"ok":true,"head":null,"body":{"message":"Hello, world!","from":"127.0.0.1:300?","pheader":"my_header"},"headers":{"as":"json"},"trace":"*"} (glob)

$ kill %1