thalassa-http-client

A simple http client for Thalassa that doesn't require ZeroMQ

Thalassa Client

A lightweight client for Thalassa

Running the Client

The client can be run any of three ways.

  1. From the command-line
  2. As a module
  3. Over HTTP

Why would you do this? Let's say you have an existing legacy Java application that you'd rather not change. You can create a sister service that invokes the command line client to register the service on it's behalf.

For example, if Thalassa is installed globally (other wise `./node_modules/.bin/thalassa-client):

thalassa-client --register myapp@1.0.0:8080 --debug

This registers the application named my app at version 1.0.0 that's on the current host on port 8080. The client will continue to ping the Thalassa server with updates.

thalassa-client --help
  Options:
    --host           thalassa host                                                    [default: "127.0.0.1"]
    --apiport        thalassa http api port                                           [default: 9000]
    --register       name@x.x.x:port,name@x.x.x:port                                  [required]
    --secsToExpire   default time in seconds for a thalassa registration to be valid  [default: 60]
    --updateFreq     time frequency in ms to ping the thalassa server                 [default: 20000]
    --updateTimeout  time in ms to wait for a registration request to respond         [default: 2500]
    --debug          enabled debug logging

Using the client from within a node.js application to register your service is simple. Pass options via the opts object like new Thalassa.Client(opts):

var Thalassa = require('thalassa');

var client = new Thalassa.Client({
  apiport: 4445,
  host: 'localhost'
});

client.register('myapp', '1.0.0', 8080);

// start reporting registrations to the server
client.start();

// stop reporting registrations to the server
client.stop();

opts.log may be passed just like the server.

The client will periodically check in with the Thalassa server according to opts.updateFreq (default 5000ms). Each registration will product a updateSuccessful or updateFailed event to be emitted.

client.on('updateSuccessful', function () {}); client.on('updateFailed', function (error) {});

Also as a module, you can use the client API to query for registrations.

client.getRegistrations('myapp', '1.0.0', function (err, registrations) {
    // registrations is an Array of Registrations
}

See the HTTP API section for the Registration structure.

You can also pass metadata with any registration as a fourth parameter. This can be any javascript object with properties. For example:

var meta = {
    az: 'use1a',
    size: 'm1.large',
    foo: {
        bar: 'baz'
    }
};
client.register('myapp', '1.0.0', 8080, meta)

License

Licensed under Apache 2.0. See LICENSE file.