channel.md

TChannel

Below we document the interface of tchannel itself.

• TChannel(options)
• listen()
• close()

The channel supports additional methods for making subchannels, and off those sub-channels sending and handling requests.

• sub-channels
• requests
• handlers

Stability: stable

var channel = TChannel(options)

To create a channel you call TChannel with some options.

var TChannel = require('tchannel');

var channel = TChannel();
channel.listen(8080, '127.0.0.1');

options.statTags

You must specify tag information for the stats support. The following four fields are available:

• required: options.statTags.app name of your app
• options.statTags.host the hostname of the server
• options.statTags.cluster the name of the cluster
• options.statTags.version the version of your application

options.statsd

You can pass a statsd instance into TChannel. If you pass a statsd client in we will hook up the 'stat' event to the statsd client.

Check out the stats document to see what stats we will emit

We recommend using uber-statsd-client

options.logger

You can pass in your own logger instance. This will default to a null logger that prints no information.

The logger you pass in must implement debug, info, warn, error and fatal methods.

We recommend using logtron

options.requestDefaults

You can specify default values for all outgoing requests on a per channel basis.

You can pass an object; for example

var channel = TChannel({
    requestDefaults: {
        hasNoParent: true,
        headers: {
            'as': 'raw',
            'cn': 'testy-test'
        }
    }
})

options.trace

There is a trace boolean that can be used to turn tracing off by setting it to false. Tracing defaults to true.

It's recommend you run with tracing permanently on.

options.traceReporter

If you want to implement a custom reporter for tracing information then you can specifiy a traceReporter function.

By default this is not needed; the hyperbahn client comes with a tcollector reporter that will be wired up for you.

channel.listen(port, host, callback?)

Starts listening on the given port and host.

• Both port and host are mandatory.
• Port must be a valid port as per host-port rules
• Host must be a valid non-ephemeral host as per host-port rules
• The port may be 0, indicating that the operating system must grant an available ephemeral port.

The eventual host and port combination must uniquely identify the TChannel server and it is strongly recommended that the host be the public IP address.

channel.hostPort

Once you've called listen the channel will have a hostPort that you can access in the case you called listen(0).

channel.close(cb)

When you want to close your channel you call .close(). This will cleanup the tcp server and any tcp sockets as well as cleanup any inflight operations.

Your cb will get called when it's finished.

channel.TChannelAsThrift

The channel exposes the TChannelAsThrift implementation. This means you only have to import tchannel and can use the thrift implementation from the channel instance

channel.TChannelAsJSON

The channel exposes the TChannelAsJSON implementation. This means you only have to import tchannel and can use the json implementation from the channel instance