streaming.md

Streaming

TChannel supports streaming as a first class use-case

Stability: unstable

In TChannel you can fully stream arg2 and arg3 as a stream of binary Buffers.

subChannel.register(name, { streamed: true }, handler)

To implement a streaming server you must call register() with a options argument to opt into streaming.

The handler interface is different when doing streaming.

handler(req, buildResponse) - you get a streaming incoming request and you get a buildResponse({ streamed: bool }) function which takes options and can be used to build a streaming or non-streaming outgoing response.

• req.arg1 A string or buffer
• req.arg2 A readable stream of buffers for arg1
• req.arg3 A readable stream of buffers for arg1

If you call buildResponse with { streamed: false } it will return the normal outgoing response as documented in the sub-channel documentation.

If you call buildResponse with { streamed: true } it will return a streaming out response with three fields. An arg1, arg2 and arg3 field, all of which are writable streams of buffers.

req = subChannel.request({ streamed: true })

To making a streaming out request you can set the streamed boolean to true.

The rest of the options are documented in the sub-channel docs.

• req.arg1 A string or buffer
• req.arg2 A writable stream of buffers for arg2
• req.arg3 A writable stream of buffers for arg3

To handle the response you should not pass a callback to .send()

Instead you should add a listener to "response" event on the request; The incoming response will have three fields; arg1, arg2 and arg3. They are all readable streams of buffers.

var req = subChan.request({
    streamed: true,
    serviceName: 'foo'
});

req.sendArg1('endpoint');
req.arg2.end('');
myStream.pipe(req.arg3);

req.on('error', function onError(err) {
    /* handle errors */
});
req.on('response', function onResponse(res) {
    // handle res.arg2 and res.arg3
});