vpp.js

VSOA app framework like Express.js

Get started

const vppjs = require('vppjs');
const vpp = vppjs.vpp();

const router = vppjs.router();
const devices = {};

router.dgram('/ping', (req, res) => {
  return res.datagram('pong');
});

router.get('/file/', (req, res) => {
  const fileId = req.payload.param;
  fs.createReadStream('./files/' + fileId).pipe(res.createStream());
});

router.set('/user/', (req, res) => {
  const userInfo = req.payload.param;
  devices[userInfo.id] = userInfo;
  res.reply('ok');
});

vpp.use('/foo', router);

API

vppjs.vpp()

Create a new instance of Vpp class.

vppjs.router()

Create a new instance of VppRouter class.

Vpp class

Event 'connect' and 'disconnect'

These events are emitted when client is connected or disconnected:

• cli: VSOA remote client object
• server: VSOA Server object

vpp.on('connect', (cli, server) => {
  // do something
})

In addition to standard VSOA Remote Client events, the cli object of vppjs will also emit 'disconnect' event on disconnection.

Vpp contructor(options)

• options: {VppOptions}
  • info: {Object}, for VSOA server info, default { name: 'Vpp.js' }
  • passwd: {String}, for VSOA server authentication
  • tlsOpt: {Object}, Node.js TLS options object, for VSOA TLS server setup
  • defaultErrorCode: {Number}, range from 128 to 255, default 199. This is used by the default error handler to send reply for unhandled server error.

const { Vpp } = require('vppjs')
const vpp = new Vpp()

vpp.start(port[, host][, backlog][, callback])

• port: {Number}, port number the VSOA server to listen
• host: {String}, host name the VSOA server to listen
• backlog: {Number}, TCP connection backlog, check Node.js document for more information
• callback: {Function}, callback function when the server socket is listening

vpp.stop ([callback])

• callback: {Function}, callback function when the server is stopped

vpp.publish ([payload][, quick][, urlpath])

• payload: {VsoaPayload}, the raw VSOA request payload object or undefined
  • param: {String|Object}, payload param data
  • data: {Buffer}, optional payload data
  • offset: {Number}, optional offset of payload data inside the given buffer
  • length: {Number}, optional length of actual payload data inside the buffer
• quick: {Boolean}, optional flag to incide normal or quick VSOA data channel
• urlpath: {String}, optional url path of publishement, defaults '/'

vpp.isSubscribed (url)

• url: {String}, url to be checked if has been subscribed by a client

VppRouter class

Note: unlike Expres.js, the Vpp or VppRouter instance for now, cannot use arbitrary (req, res, nex) => {} middleware function, but router intances only!

router.use(subPath, ...routers): VppRouter

• subPath: {String}, the mounting url sub path (relative to the parent router/vpp) for the given sub routers
• routers: {VppRouter}, the sub routers to mount

router.get(subPath, ...getHandlers): VppRouter

• subPath: {String}, the mounting url sub path for the given RPC handlers.
• getHandlers: {VppRpcHandler}, handlers that will be called once there are GET RPC calls to the joined URL (parent url path + subPath).

router.set(subPath, ...setHandlers): VppRouter

• subPath: {String}, the mounting url sub path for the given RPC handlers.
• setHandlers: {VppRpcHandler}, handlers that will be called once there are SET RPC calls to the joined URL.

router.dgram(subPath, ...dgramHandlers): VppRouter

• subPath: {String}, the mounting url sub path for the given Datagram handlers.
• dgramHandlers: {DgramHandler}, handlers that will be called once there are DGRAM messages sent to the joined URL.

router.publish([payload][, quick][, subPath]): VppRouter

• payload: VppPayload or undefined
• quick: {Boolean}, optional flag to incide normal or quick VSOA data channel
• subPath: {String}, optional url path of publishement, defaults '/'.

VppPayload

When working with VppRouter object, APIs that accept VppPayload can help automatically convert it into the raw VsoaPayload:

1. If input is an object and
   • a. it contains 'param' field then raw VSOA payload is assumed;
   • b. it contains 'data' field of Buffer then raw VSOA payload is assumed;
   • c. OTHERWISE plain object is assumed, send it as 'param'.
2. if input is string, send it as 'param'.
3. if input is Buffer, send it as 'data'.
4. if input is number, convert it to string then send it as 'param'. This is because VSOA IGNORES number in payload.param.
5. otherwise, input will be IGNORED.

VppRpcHandler(req, res[, next])

If this function returns a Promise, routers mounted after this one will be called once it is resolved, otherwise the router chain will break if the promise is rejected.

If this function returns anything other than a promise object. Developer can still use the last next callback to trigger following routers. If next is omitted, Vpp will break the router chain right after currrent handler call.

• req: VppRpcRequest
• res: VppRpcResponse
• next: optional Node.js style callback function

VppRpcRequest

req.cli

VSOA RemoteClient object, which could be used to call original VSOA client API.

req.url

A string of the targeting url of the incoming RPC call.

req.seqno

Number of the raw RPC call seqno.

req.method

Enum value of VsoaRpcMethod, an integer number of VSOA RPC call method: 0 = GET, 1 = SET.

req.payload

Incoming raw {VsoaPayload} object, see publish section

VppRpcResponse

res.server

Raw VSOA Server object, which might be used for advanced usecases.

res.reply(payload[, code][, segno]): VppRpcResponse

• payload: {VppPayload}, see VppPayload section.
• code: {Number}, optional VSOA status code, default 0.
• seqno: {Number}, sequence number to respond, default to the one from req.

res.publish([payload][, url]): VppRpcResponse

• payload: {VppPayload} or undefined, see VppPayload section.
• url: {String}, optional url to publish, default to the incoming RPC call url.

res.datagram(payload[, url]): VppRpcResponse

• payload: {VppPayload}, see VppPayload section.
• url: {String}, optional url to send the datagram, default to the incoming RPC call url.

res.createStream([payload][, timeout[, code[, seqno]]]): VsoaStream

• payload: {VppPayload|undefined}, see VppPayload section.
• timeout: {Number}, optional timeout in milliseconds, use default VSOA value.
• code: {Number}, optional RPC reponse code, default 0.
• seqno: {Number}, optional RPC sequence number, default to the one from req.

VppDgramHandler(req, res[, next])

Router handling logic is same as VppRpcHandler.

• req: {VppDgramRequest}
• res: {VppDgramResponse}
• next: Node.js style callback function

VppDgramRequest

dgramReq.url

A string of the targeting url of this incoming datagram.

dgramReq.cli

VSOA RemoteClient object, which could be used to call original VSOA client API.

dgramReq.payload

Incoming raw {VsoaPayload} object, see publish section

dgramReq.quick

Boolean flag indicating if this datagram was sent via the quick data channel.

VppDgramResponse

dgramRes.server

Raw VSOA Server object, which might be used for advanced usecases.

dgramRes.publish(payload[, url]): VppDgramResponse

• payload: {VppPayload}, see VppPayload section.
• url: {String}, optional url to publish, default to the incoming datagram's url.

dgramRes.datagram (payload[, quick][, url]): VppDgramResponse

• payload: {VppPayload}, see VppPayload section.
• quick: {Boolean}, optional flag to incide normal or quick VSOA data channel
• url: {String}, optional targeting url of this replying datagram, default to the incoming datagram's url.

TODO

• [ ] more unit tests
• [ ] vpp middleware can intercept all sub route requests
• [ ] accept error handlers
• [ ] simple request logging middleware
• [ ] scaffolding scripts